Summary

Positive crankcase ventilation has been used since the 1910s to reduce engine wear by drawing corrosive “blowby” vapors out of the crankcase. Starting in 1961, the U.S. auto industry voluntarily adopted positive crankcase ventilation as a way to reduce hydrocarbon emissions. This was a cynical effort to derail California’s exhaust emissions standards, which was unsuccessful, and triggered a new political battle over crankcase emissions controls. The same automakers who had proclaimed positive crankcase ventilation a cheap solution to the smog problem fought bitterly to delay state and federal efforts to make such systems mandatory. However, crankcase emissions controls are now required by law in the U.S. and most other countries.

When was positive crankcase ventilation first adopted on U.S. cars? Why was it adopted? Many sources, including some academic textbooks, will tell you it was required by California regulations starting in 1961, but that’s not true at all. Here is the full story of how the American auto industry found a new use for an old technology and briefly promoted positive crankcase ventilation as a cheaper alternative to auto exhaust controls, only to immediately reverse course and spend the next few years fighting tooth and nail against regulations that would require crankcase emissions controls for all new cars and trucks.

Crankcase Blowby

Any internal combustion engine faces an important design challenge: keeping its air-fuel mixture and combustion products separate from the lubricating oil in the engine crankcase. Reciprocating engines do this with a series of sealing rings around each piston; in a rotary engine, this is mostly the job of the apex seals.

Piston rings and other such internal seals are necessarily a compromise: If they seal too tightly, they create excessive friction, which costs power; if they don’t seal tightly enough, “blowby” will dilute the oil supply with fuel and exhaust gas. Even with good sealing, there is always some blowby, especially during break-in and on older engines, and blowby increases with engine speed and load.

Gasoline and combustion products are corrosive, which contributes to rapid wear and the formation of sludge in the crankcase. Blowby also introduces water vapor into the crankcase, which then recondenses in a separate layer from the oil, creating problems with corrosion and freezing. Early engines dealt with this problem by venting excess crankcase vapor to the atmosphere. This wasn’t always sufficient, so many car and truck engines added a breather and a road draft tube. With the vehicle in motion, a partial vacuum at the end of the draft tube would draw ventilating air through the filtered breather cap into the crankcase. The airflow removed water vapor and the light ends of oil contamination, which was then drawn out through the road draft tube and exhausted under the vehicle.

For passenger cars, a breather/draft tube system was generally considered adequate, although it had some limitations. Road draft ventilation was dependent on road speed, so it worked better at higher speeds than in urban traffic. Also, if the draft tube were improperly installed or damaged, it could result in negative inlet flow, causing crankcase vapor to flow out through the breather into the engine compartment. Road draft tubes were impractical for stationary engines and not very satisfactory for slow-moving vehicles: There wasn’t enough airflow at low speeds, and the breather filter could easily be overwhelmed by wet, dirty, or dusty conditions.

Positive Crankcase Ventilation

An alternative to the road draft tube system was positive crankcase ventilation, either using an external blower or taking advantage of a spark ignition engine’s intake manifold vacuum to draw air through the crankcase. This air could then either be exhausted to the atmosphere or drawn back into the air cleaner or intake manifold to be burned. While diesel engines are unthrottled and have no manifold vacuum, a similar strategy can be used with diesel engines where needed by exploiting the pressure surge from the closure of the intake valves.[1] Turbodiesel engines can also draw crankcase ventilation air from the intake side of the compressor.[2]

Because this type of positive crankcase ventilation wasn’t widely adopted for passenger car engines until the early 1960s, there’s a frequent presumption that it was a new invention at that time. For example, in his book Moving Violations: Automobiles, Experts, and Regulations in the United States, Lee Vinsel incorrectly calls it as “a new pollution control technology” developed by General Motors.[3]

In fact, positive crankcase ventilation was a much older concept that had already seen fairly extensive use in nonautomotive applications. As an October 23, 1919 item in the trade journal Automotive Industries noted:

In certain classes of engines, such as large Diesel engines, farm lighting set engines, etc., it is customary to draw all or part of the air for the combustible charge through the engine crankcase, with the object of preventing the formation of explosive mixtures in the crankcase or of the entry of foul vapors from the crankcase into the room where the engine is operating. It occurs that this practice might prove advantageous in automobiles, as it would tend to keep the oil in the crankcase cooler and to eliminate from it some of the unconsumed fuel constituents that find their way past the pistons.[4]

In 1924, a University of Utah student named Ivan L. Anderson published a paper in the SAE Journal describing his experiments with positive crankcase ventilation, using a six-cylinder Buick engine. He found that “by passing all the air that entered the carburetor through the crankcase first,” oil dilution was greatly reduced and crankcase temperatures were reduced by about 20 degrees Fahrenheit. Oil consumption increased slightly, but fuel consumption was reduced by about 4.5 percent while “almost entirely eliminating crankcase-oil dilution.”[5]

Early PCV Systems

Despite its promise, positive crankcase ventilation wasn’t widely adopted for passenger car use before World War 2. There were a few passenger car applications — Viking, the short-lived Oldsmobile companion make of 1929–1931, used a tube to draws crankcase vapors into the air cleaner[6] (a simple “air-cleaner-aspirated” PCV system) — but most automakers were content with road draft tubes.

However, positive crankcase ventilation did find some application in heavier vehicles. For example, The White Motor Company adopted an air-cleaner-aspirated crankcase ventilation system for its Model 61 truck in 1929,[7] and by the late 1930s, there was some operator interest in positive crankcase ventilation for truck and bus engines, primarily as a way to reduce cold sludge and corrosion due to condensation in the crankcase oil. This subsequently led the U.S. Army to become interested in positive crankcase ventilation by the winter of 1941.[8]

By 1942, the Army was installing vacuum-controlled crankcase ventilators on vehicles like the U.S. DUKW-353 2½-ton 6×6 amphibian truck (inevitably known as the “Duck”), whose 269.5 cu. in. (4,416 cc) six-cylinder engine used manifold vacuum to draw blowby and water vapor out of the crankcase, controlling the vapor flow with a spring-loaded plunger valve. The system incorporated a separate crankcase breather with its own oil-bath air cleaner.[9]

One downside of such installations was that they required periodic maintenance: Over time, the ventilation tube and/or control valve became plugged with carbon, so if the system wasn’t regularly cleaned or replaced, it could produce excessive crankcase pressure. Although even very simple exhaust eductor PCV systems were quite effective in reducing engine corrosion and wear, commercial users were often deterred by the additional maintenance requirements.[10]

After the war, Fram Corporation tried to market an add-on PCV system for passenger car owners, advertising it as an “engine-saver” that “really stops auto sludge.” Rather than manifold vacuum, the Fram Positive Crankcase Ventilator used a small electric blower attached to the breather cap, drawing air through its own replaceable cartridge filter.[11] Other positive crankcase ventilation systems also saw some use on fleet vehicles like taxicabs.

A few non-U.S. automakers adopted PCV systems during this period, including the Soviet Moskvich 407[12] and GAZ-21 Volga[13]. However, Detroit manufacturers still weren’t terribly interested in positive crankcase ventilation for general passenger car use. A 1949 paper by Ford engineer B. Gratz Brown remarked that “some of the commercial systems did not produce the desired results,” and noted the “serious handicap” of plugging or gumming due to carbon deposits. Brown also observed that without an external blower, “none of these systems is really positive,” and concluded that “a road draft tube with an impact-type breather can be properly worked out so as to fulfill average requirements.”[14]

Reducing Smog

Although Automotive Industries had noted back in 1919 the potential benefit of eliminating “foul vapors from the crankcase,” early positive crankcase ventilation (PCV) systems were intended to reduce internal wear and corrosion — emissions control was not their object. Some PCV systems, like the Fram Positive Crankcase Ventilator, still used a road draft tube, and even those that returned blowby to the engine typically vented excess blowby to the atmosphere.

Nonetheless, crankcase emissions — which consisted of about one part exhaust gas to four parts unburned air-fuel mixture — did contribute to total hydrocarbon emissions, which became a matter of concern in the 1950s, after Arie J. Haagen-Smit identified atmospheric hydrocarbons as a key smog component. As engineers from the California Motor Vehicle Pollution Control Board noted in a 1963 technical paper:

The significance of vehicular hydrocarbon losses lies not in their direct effects as air pollutants, but in their participation in the photochemical reactions which result in the phenomenon known as photochemical smog.[15]

How much crankcase emissions contributed to that problem was unknown. A widely cited 1952 paper by Jack Q. Payne and Harrison W. Sigworth of the California Research Corporation estimated that crankcase blowby gases contained about three times as much “noxious products” as engine exhaust. However, that study calculated that crankcase blowby represented a very small fraction of total emissions in any given operating regime — less than 1 percent for engines in good condition, no more than 5 percent for high-mileage engines in poor mechanical condition.[16]

Payne and Sigworth were careful to note, “No effort has been made in this study to measure or estimate the over-all contribution of blowby and exhaust gases to any specific air pollution problem.” However, until 1960, theirs was virtually the only research to examine blowby emissions at all, and their findings led to a general presumption that crankcase emissions were relatively inconsequential. As a result, crankcase emissions weren’t included in the 1955–1956 Coordinating Research Council field survey of automotive emissions, which sought to establish the “baseline” emissions of cars without emissions controls.[17] Air Pollution Foundation president William L. Faith didn’t even mention crankcase blowby in the automobile chapter of his 1959 book Air Pollution Control.[18] A paper entitled “The Smogless Auto,” presented by researchers from Union Oil at the Air Pollution Control Association (APCA) annual meeting in June 1959, acknowledged crankcase vents as one of the five sources of automotive air pollution, but didn’t count crankcase emissions among the areas in need of “remedial action.”[19]

California Emissions Standards

By the time the latter paper appeared, smog-choked California was laying the groundwork to mandate “remedial action.” On April 28, 1959, California Gov. Edmund G. (Pat) Brown signed a bill called the Rees-Richards Act (S.B. 117), which declared that “the discharge of air pollutants from the exhausts of motor vehicles constitutes one of the most serious threats to the heath of the people of this State.” The new law gave the California Department of Public Health until February 1, 1960 to establish “maximum allowable standards of exhaust contaminants from motor vehicles which are compatible with the preservation of the public health including the prevention of irritation to the senses.”[20]

Because there had been so little research on crankcase emissions, crankcase blowby was not part of the inventory of hydrocarbon sources that the health department’s Bureau of Air Sanitation examined in establishing the auto emissions standards. As the bureau chief and senior sanitation engineer explained in a presentation at the APCA annual meeting in May 1960:

At the time standards were being developed it was assumed that crankcase vent gases represented only a small percent of the exhaust hydrocarbons. This assumption was based on published studies⁶ and available data on hydrocarbon losses from all sources. As a result, the exhaust standards did not take “blowby” into account.[21]

(Their footnote 6 referred to the 1952 Payne and Sigworth paper.)

California subsequently added a crankcase emissions standard, but that didn’t come about until December 1960 — a year after the original standards, and more than a year after the Automobile Manufacturers Association (AMA) announced that it would voluntarily install PCV systems on California-bound vehicles.

GM Research Laboratories Study

How that came about is a complicated story that began in the General Motors Research Laboratories. Sometime around the first half of 1959, a team of GM research engineers had conducted a new study on blowby vapor, which the researchers later described as an unanticipated offshoot of a different project studying engine corrosion in high-humidity conditions. That earlier project had suggested that hydrocarbon emissions from crankcase blowby were much higher than previously assumed: “actually some 30 times (rather than three times) that of exhaust gas.”[22]

Based on infrared analysis of crankcase emissions from five cars (three 1959 models, one 1955 car with about 41,000 miles, and one 1950 model with about 59,000 miles), the GM researchers concluded that the hydrocarbon content of blowby emissions was so much higher than the HC content of exhaust gases that crankcase HC emissions were actually equal to or greater than exhaust emissions, even though exhaust flow was much greater than crankcase gas flow.

The researchers then installed positive crankcase ventilation systems on all five cars, removing the draft tube and routing the crankcase vent gases back into the intake manifold of each engine, below the carburetor. This completely eliminated crankcase gas emissions for the three newer cars and greatly reduced them for the two older ones. The researchers estimated that adding positive crankcase ventilation reduced the test cars’ total hydrocarbon emissions by between 20 and 70 percent, depending on road speed.

Even if we assume that this study was conducted in good faith — which it may have been — there were some very questionable aspects to its premises and methodology. For one, while the research team claimed that the test vehicles covered “the range of results observed in a number of studies,” they presented data for only five cars. Since it was well-known that blowby could vary by up to a factor of 10 depending on engine age and condition, it was unclear how representative the five test cars actually were. For another, the exhaust HC emissions the researchers recorded for the test cars were unusually low compared to other contemporary studies of uncontrolled exhaust emissions.

When the research was finally released in 1960, outside stakeholders would raise all of these points. However, in the interim, the GM study would become the basis of a self-serving political gambit by the Automobile Manufacturers Association (AMA).

The AMA Takes a Hand

First organized in 1913 as the Automobile Chamber of Commerce (the name changed in 1934), the AMA was a nonprofit trade association whose members include nearly all domestic automakers, as well as truck, bus, and motor coach manufacturers like Mack, Reo, and International Harvester. The association’s president in 1959–1960 was Chrysler Corporation president L.L. (Tex) Colbert.

Among the stated functions of the AMA was to act as a clearinghouse for the exchange of technical information and intellectual property, such as patents and trademarks. Beginning in 1953, the AMA also took on the task of coordinating the industry’s response to the auto emissions problem. This was managed as a cooperative effort through the Vehicle Combustion Products (VCP) Committee, a new subcommittee of the AMA’s powerful Engineering Advisory Committee (EAC), which was made up of the engineering vice presidents of the member companies.

The ostensible purpose of the industry’s cooperation on auto emissions was, as GM engineering VP Charles A. Chayne (then chairman of the EAC) put it in 1954, “to set aside for a time our concern about the immediate advantages of competitive action, and apply the combined talents and facilities of the whole industry to the solution.”[23]

However, another important goal of this cooperative effort (which the EAC privately affirmed in January 1958) was to allow the auto industry to establish a united front on the emissions question, controlling access to information and establishing a policy of “a single announcement and a uniform adoption date for any device which the industry may decide to use for smog control.”[24]

Beginning in the mid-sixties, critics of the auto industry, including Los Angeles County Supervisor Kenneth Hahn and consumer advocate Ralph Nader, contended that automakers had used this cooperative program — which included a royalty-free cross-licensing agreement for certain emissions-related technology — to stymie and delay automotive emissions controls. Both the uniform adoption policy and the structure of the cross-licensing agreement were also tailored to prevent any individual manufacturer from gaining a competitive advantage in the area of emissions control, which raised significant antitrust questions.

In 1966, the U.S. Department of Justice launched a 15-month federal grand jury investigation into the matter, which led to a 1969 federal lawsuit against the AMA and its member companies under the Sherman Antitrust Act, an 1890 anti-monopoly law prohibiting activities that restrict competition in interstate commerce.

That suit was subsequently settled with a consent decree, and the federal judge who approved it ordered all records of the grand jury investigation sealed.[25] However, in May 1971, Rep. Phillip Burton (D-Calif.-5), who had urged an open trial, obtained a copy of a DOJ memorandum about the grand jury investigation, which he introduced into the congressional record on May 18.[26] Although the excerpts of the grand jury evidence that memorandum contains are fragmentary, they’re also quite damning — the DOJ officials who wrote the memo had recommended criminal rather than civil antitrust action against the auto industry — and they’re very revealing of what the AMA tried to do with crankcase emissions controls.

The Vehicle Combustion Products Committee and the “Uniform Adoption” Policy

In the summer of 1959, probably less than three months after Gov. Brown signed the Rees-Richards Act, GM took the results of the GM Research Laboratories study on crankcase emissions to the AMA Vehicle Combustion Products committee. In July, the committee discussed whether the auto industry should jointly adopt positive crankcase ventilation (and possibly also fuel system evaporative controls), in keeping with AMA policy on uniform announcement and adoption of any smog-reduction measures.

While GM apparently felt obligated to defer to the AMA on this, AMA smog project manager George A. Delaney pointed out a snag: the existing industry agreement didn’t actually cover crankcase or evaporative emissions. In an internal memorandum to the Engineering Advisory Committee on July 27, AMA Engineering and Technical Division manager William F. Sherman noted:

Mr. Delaney called attention to the fact that neither of these areas of investigation or development are covered by the present industry Cross-Licensing Agreement. It was, therefore, the unanimous recommendation of the [VCP] committee and of Mr. Delaney that the Engineering Advisory Committee should immediately request the AMA Patent Committee to amend the Cross-Licensing Agreement to cover these areas, and to do so in the immediate future to permit the work to go forward rapidly.[27]

The cross-licensing agreement was subsequently so amended.

Although this might sound trivial, Justice Department officials later argued that this sequence of events was evidence of the basically collusive, anti-competitive intent of the industry’s cooperative efforts on smog control. As the DOJ memorandum released by Rep. Burton emphasized:

General Motors could have installed the [PCV] device on its cars and obtained a competitive advantage since this type of device was not covered by the cross-licensing agreement. However, this was not done, but to the contrary, the cross-licensing agreement was amended in 1960 by the addition of five categories covering crankcase and evaporation losses so that the industry could act collectively with regard to these areas. … Quite evidently the cross-licensing agreement was not needed for protection or use of any patent. As a matter of fact, no significant patents were then known to exist affecting development of pollution control devices and no lists of patents were then nor have they ever been annexed to the cross-licensing agreement or any extension thereof. … It is submitted that the cross-licensing agreement was merely a vehicle to accomplish the non-competitive and delaying activities of the signatories thereto.[28] [Emphasis added.]

Indeed, GM not only agreed to relinquish any competitive advantage, they also took it upon themselves to keep the whole matter secret until the AMA directed otherwise. In an interoffice memo in October 1959, Cadillac assistant chief engineer Robert J. Templin warned the division’s purchasing manager, John H. Lamb, that “we are bound by an agreement through [GM Engineering vice president] Mr. C. A. Chayne with the Automobile Manufacturers Association to withhold any public knowledge about these [crankcase ventilation] devices until a joint announcement can be made through AMA. These devices must, therefore, be treated as confidential.”[29] Such secrecy was curious given that the technology was by no means new, and had been in actual if limited use for decades. The intent of the confidentiality was evidently to discourage what the AMA Engineering Advisory Committee later termed “ill-considered unilateral publicity” regarding smog control.[30]

Interestingly, when the GM crankcase emissions research was finally released in early 1960, members of the VCP committee offered contradictory statements about the timeline of events. Chrysler engineer Charles M. Heinen proclaimed, “In a period of less than six months the industry committee reviewed the data, made confirmatory investigations, examined the engineering difficulties, and recommended that action be taken.”[31] However, Bob Templin then claimed that the VCP did not learn of the GM Research Labs crankcase study until August 1959, offering this inspirational but misleading account:

IN AUGUST, 1959, when the magnitude of the crankcase problem was first clearly established, the authors presented their findings to the Vehicle Combustion Products Committee of the AMA, the socalled [sic] VCP. The members of VCP were quick to see both the magnitude of the problem as well as the strong possibility that something beneficial could be done about it. A special VCP committee was formed of AMA member companies to pursue the development of a device for eliminating the crankcase emission problem. … In November, 1959, the special committee’s assignment was completed and action was taken by the industry to announce publicly that the system will be available on all American-built 1961 vehicles sold in California.[32]

“Possibly Slow Down Any Regulatory Action”

It’s not clear when the AMA board actually voted on the VCP recommendation to adopt positive crankcase ventilation for California, but the AMA elected not to announce the decision until late November.

The timing of the AMA announcement was a very calculated political decision. While the AMA knew that the California auto emissions standards would be finalized in the near-future, they also knew that those standards wouldn’t have the force of law until the Legislature determined if, when, and how to actually implement them. The AMA therefore decided that their immediate priority was to delay legislative action.

Although supervisors from Southern California counties, which suffered the worst smog, were pressuring Gov. Brown to immediately call a special legislative session to address the auto emissions issue, Brown said he preferred to wait until the Department of Public Health had issued its final standards, a preliminary version of which were announced on November 2.[33] Four days later, on November 6, the health department Bureau of Air Sanitation announced that the standards would be finalized in early December.[34]

A week later, in an internal memorandum dated November 13, 1959, American Motors director of automotive research Wallace S. Berry — a member of the AMA Engineering Advisory Committee — wrote that the AMA would soon announce the adoption of positive crankcase ventilation for 1961 models, even though testing and engineering validation wasn’t yet finished. In that memo, Berry explained:

The reasons for making the announcement before test work is completed are as follows:

1. The opportunity for the industry to voluntarily do something in California which will make a major reduction in emissions at a relatively low cost. In advancing this argument the AMA Staff uses a cost to the customer figure of around ‘$10.’
2. On December 4th there will be a hearing in Berkeley which will be held between the California State Department of Health to finalize recommendations on tailpipe emissions. An announcement before that date would possibly slow down any regulatory action on this matter. Likewise, this announcement may deter Governor Brown from holding a special session of the Legislature dealing with the air pollution problem.[35] [Emphasis added.]

On November 30, at a press conference called by Los Angeles County 5th District Supervisor Warren M. Dorn, William Sherman and members of the VCP committee announced that all U.S.-made 1961 California cars would have positive crankcase ventilation, which they characterized as a new way to combat a theretofore unrecognized proportion of automobile hydrocarbon emissions.

At that time, the AMA hedged on the issue of cost,[35] but within a few days, AMA representatives clarified that PCV devices would be only a few dollars — much less costly than still-unproven exhaust controls.[37] By the following spring, automakers would be citing the $10 figure Berry had mentioned.[38]

California Standards Finalized

As they had previously announced, California Department of Public Health officials held a hearing in Berkeley on December 4 to issue their final automobile emissions standards. These called for massive reductions in exhaust emissions: a 60 percent reduction in carbon monoxide and an 80 percent reduction in exhaust hydrocarbons.

Neither evaporative emissions (from fuel tank and carburetor vents) nor crankcase emissions were included. The department’s Bureau of Air Sanitation had been caught off-guard by the AMA positive crankcase ventilation announcement, and since GM had not yet released the research on which the AMA move was ostensibly based, there was no way for the bureau or the department to meaningfully respond. (Even if they had, crankcase emissions were arguably outside the health department’s original statutory mandate, which had specified “exhaust contaminants.”)

It’s not difficult to see what the AMA hoped to accomplish: As both GM and the AMA likely knew, county and state officials in California had been repeatedly warned by their legal counsels that any rule or regulation lacking “proper technical substantiation” risked being overturned as “arbitrary, unreasonable, capricious, or confiscatory,” a concern L.A. County staff had recently reiterated at the 1959 APCA annual meeting in June.[39] The automakers thought they had found a blind spot, an aspect of the smog problem that had previously gone largely unrecognized, but for which the industry could claim to have already devised an inexpensive solution.

Automakers were already well aware that exhaust emissions controls were going to be costly. By shifting the focus to crankcase emissions, the AMA was implying that state officials and exhaust control proponents didn’t really have a good handle on the scope of the problem, which the association apparently hoped would give the governor and the Legislature pause when it came to enforcing the new exhaust standards.

Under other circumstances, this might have worked, perhaps even sending California health officials back to the drawing board, but the AMA had misjudged the political urgency of the smog issue. While Gov. Brown’s reluctance in November to call a special legislative session may have seemed like prevarication, Brown had really just wanted the health standards in place to justify invoking the state’s police power. He didn’t need the initial automobile standards to be comprehensive — he needed a legal basis that could survive a constitutional challenge, and the December 4 standards gave him that. Further details could be ironed out later; the Rees-Richards Act provided for periodic revisions of the standards.

Back in November, Brown had warned, “If anyone thinks we don’t mean business in our attempt to whip this smog problem, they should think again. The automobile manufacturers had better take notice of our problems and get ready.”[40] He was true to his word: On January 5, 1960, scarcely a month after the Department of Public Health had approved its motor vehicle exhaust standards, Brown announced that he would call an extraordinary session of the Legislature to tackle the smog problem[41] — exactly the action the AMA had hoped their positive crankcase ventilation announcement would deter.

Going Public

The GM Research Labs team belatedly presented their crankcase emissions paper at the SAE annual meeting in Detroit on January 15, read by coauthor Richard A. Randall. In the wake of the unexpected AMA announcement, there was sufficient interest that the talk was covered by the Associated Press[42] — unusual for a technical presentation. The study was published in SAE Transactions later in 1960.[43]

Judging by the discussion in SAE Transactions, the GM study’s most provocative claim was their assertion that crankcase blowby constituted as much as 40 percent of total hydrocarbon emissions. The authors asserted:

Deceleration emissions account for 30% of the exhaust emissions; idle, road load, and acceleration emissions account for the other 70%. Crankcase emissions — equal to idle, road load, and acceleration exhaust emissions — are equivalent to 70% of the exhaust emission. Converting to a total emission basis, crankcase hydrocarbon emissions amount to 70/170 or 40% of the entire engine hydrocarbon emission (exclusive of carburetor vent losses). Therefore, it must be concluded that crankcase hydrocarbon emission is a major portion of the automobile’s contribution to air pollution.

Even with the qualification about its being “exclusive of carburetor vent losses,” the 40 percent claim was significantly higher than previous estimates — enough higher to make it suspect. Leslie A. Chambers of the Los Angeles County Pollution Control District commented:

There were no data given in the paper as to how the individual findings were weighed to arrive at this 40% estimate, but it is our feeling that a conservative weighing was used in view of some extremely high blowby volumes recorded in the paper. The Air Pollution Control District has not observed blowby volumes to be as high as those reported by the authors.[44]

Researchers from the California Research Corporation described their own tests of six late-model cars, which had much lower crankcase emissions than GM reported. They said:

If our figures for blowby rates are correct, then blowby hydrocarbon emissions may be on the order of 20–25% of the total from the engine, rather than 40% as found by General Motors. The absolute exhaust hydrocarbon emissions in pounds per hour were quite low for the five General Motors test cars as compared to the more generally accepted figures … blowby may actually contribute as little as 10–15% of the total engine hydrocarbon emissions.[45]

Air Pollution Foundation president William L. Faith conceded that the adoption of “an inexpensive device to control blowby emissions is very encouraging,” but he insisted that it had “little, if any, effect” on the need for exhaust controls, noting even if crankcase controls usefully reduced hydrocarbon emissions, they didn’t meaningfully affect carbon monoxide emissions.[46] This seems to have been the general scientific consensus. No one seriously questioned that reducing crankcase emissions was worthwhile, especially if it could be accomplished for relatively low cost, but it wasn’t enough: Even if it really did reduce hydrocarbon emissions by 40 percent, which was doubtful, that was only half the HC reduction California officials had called for.

At the same time, GM and the AMA had overplayed their hand. In their zeal to emphasize the value of their voluntary gesture (whose benefits they had likely overstated), they had inadvertently opened a second front in the war on smog.

California Gets Serious

The California Legislature’s special session was convened in March 1960 and ran through April. Out of that session came the Motor Vehicle Pollution Control Act (Assembly Bill No. 17),[47] which established a framework for actual implementation of the new auto emissions standards, to be overseen by a new Motor Vehicle Pollution Control Board.

Gov. Brown also approved a separate measure (Assembly Bill No. 19) that directed the Department of Public Health to “take into account all emissions from motor vehicles rather than exhaust emissions only” in future revisions of the standards, eliminating any question about whether the department had the statutory authority to set standards for automotive crankcase and evaporative emissions.[48]

Around this time, the California Department of Public Health published its technical report on the new standards, which noted rather defensively:

Since the time of adoption of the standards, information has been published which indicates that crankcase vent gases (“blowby”) are a substantial source of hydrocarbon emissions. This source was not included in the source inventory used in the development of the hydrocarbon standard. At the first revision of the standards, this source will also be taken into consideration. These standards represent a first attempt to establish vehicular emission standards. Judgments and decisions have of necessity been made on the basis of the present state of knowledge of the smog problem.[49]

In December 1960, the department’s Bureau of Air Sanitation revised the automobile standards to add a crankcase standard,[50] which limited crankcase hydrocarbon emissions to no more than 0.15 percent of supplied fuel by weight.[51] This meant that the positive crankcase ventilation systems that the AMA had volunteered to install would eventually become compulsory in California — in addition to rather than instead of exhaust controls — which was not at all what the industry had had in mind.

Open and Closed

In the meantime, the promised positive crankcase ventilation systems were installed on 1961 California-bound cars and trucks. Most manufacturers treated them as mandatory options: compulsory for California vehicles, but installed at extra cost. On a 1961 Chevrolet, the price was $5.40, which was about average.[52]

There was an assortment of different early PCV systems, which fell into four general categories. The most common drew crankcase blowby into the intake manifold below the carburetor, using metering valves controlled by either intake manifold vacuum (Type I systems) or crankcase vacuum (Type II systems).

Some early systems were air-cleaner-aspirated (Type III systems), drawing blowby gases into the air cleaner through a ventilation tube, with no metering valve. A few were combination (Type IV) systems, using a metering valve to draw blowby into the intake manifold at idle or part-throttle and diverting excess blowby into the air cleaner under heavy load. (To our knowledge, none of the systems fitted to production cars used electric blowers like the old Fram Positive Crankcase Ventilator, presumably for cost reasons.)

Most of these early systems were “open,” meaning that that excess blowby gases were still vented to the atmosphere under some driving conditions. For this reason, open systems didn’t completely eliminate crankcase emissions, although they were greatly reduced in most driving. Only the combination systems were “closed,” allowing no crankcase gases to escape to the atmosphere.[53]

The biggest downside of all four types, as earlier users had found, was that they needed regular maintenance. Some manufacturers recommended inspection intervals of as little as 5,000 miles, and the PCV metering valve generally needed to be replaced about once a year, although few owners actually did so.[54] In November 1960, the California Motor Vehicle Pollution Control Board resolved that it would not certify crankcase emissions control devices unless they had an effective life of at least one year.[55] The final regulations, approved in January 1961, also added some other requirements, including the ability “to operate efficiently for at least 12,000 miles with normal maintenance” and a stipulation that the devices be “so designed as to have no adverse effect upon engine operation or vehicle performance.”[56]

The certification process, which began in early 1961, was a curious conundrum: Most new cars sold in California now had the PCV systems the AMA had agreed to voluntarily install. These were not yet required by law, but automakers now had to submit them to the Motor Vehicle Pollution Board for approval, and they would become mandatory one year after the board had certified at least two suitable systems. This process took over a year, with the first batch of approvals granted in April 1962.[57]

Federal Pressure for Crankcase Controls

In the meantime, federal authorities were taking an interest in crankcase emissions. Following the GM presentation in Detroit, the Public Health Service of the U.S. Department of Health, Education, and Welfare (HEW) conducted its own study of the exhaust and crankcase emissions of 13 cars built between 1955 and 1959, “to substantiate the more recent studies and due to the possible importance of this emission source from a national standpoint.”[58]

Although the individual results varied considerably, the tests found that crankcase blowby accounted for 24 percent of the total hydrocarbon emissions of six-cylinder engines, and 33 percent of the total HC emissions of V-8 engines — less than GM had claimed, but still substantial. These results were presented at a meeting of the Air Pollution Control Association in Cincinnati in May 1960.

Even before that meeting, Sen. Richard L. Neuberger (D-Ore.) had publicly questioned why automakers did not install crankcase controls on all new cars, not just those sold in California. Neuberger made that suggestion in a January 16, 1960 letter to Chrysler president L.L. “Tex” Colbert, then still the president of the AMA. Colbert replied that the industry would offer crankcase controls “to anyone who wants it in any area of this country,” but said the industry didn’t think it “would be appropriate to burden car buyers [outside California] … with the added cost of a device for which there is little need.”[59]

In April 1961, an editorial in the Washington Post and Times Herald quoted HEW Secretary Abraham A. Ribicoff as saying that crankcase emissions controls “should be put into use as rapidly as practicable.” Ribicoff added, “If the automobile industry does not make the device standard equipment, then legislation to require it should be considered.”[60]

Most U.S. automakers could have standardized positive crankcase ventilation by the 1962 model year. In an internal memorandum dated January 10, 1961, Ford engineering executive James M. Chandler, then the chairman of the AMA VCP committee, related a recent conversation with John Asselstine of Ford Engine and Foundry about PCV system, noting that Asselstine “sees no reason why they could not be applied on all production in 1962,” including on all Ford commercial vehicles.[61] At a VCP Crankcase Ventilation Task Group meeting on January 26, American Motors and Studebaker-Packard representatives agreed that their companies could install positive crankcase ventilation on all their 1962 cars if needed.[62]

Nonetheless, the AMA rejected Ribicoff’s request, again insisting that there was “no evidence to indicate that it [positive crankcase ventilation] would serve a useful purpose for communities in other areas” outside California.[63]

On May 22, Sen. Maurine Neuberger (D–Ore.), who had recently won the Senate seat of her late husband Richard, sent a letter to 14 U.S. car and truck manufacturers, warning that if the auto industry did not voluntarily install crankcase emissions controls, Congress would pursue legislation to require such controls.[64] Three days later, William Sherman of the AMA staff send a memo to the Engineering Advisory Committee, advising member companies that such letters “be referred to AMA for a reply.” While Sherman warned that “it seems certain that there will be Federal legislation” if the industry didn’t take action voluntarily,[65] the AMA elected to stonewall.

According to a GM internal document from early June 1961, the AMA requested member automakers to provide technical reasons why it wouldn’t be desirable to install PCV devices on all new cars. Glen R. Fitzgerald, director of engineering and equipment sales of GM’s AC Spark Plug Division (which manufactured many early PCV systems), remarked, “It must be recognized that they are specifically looking for problems that will justify a negative decision.”[66]

On August 7, Ribicoff reiterated his earlier threat, this time adding a deadline: If automakers did not voluntarily agree by January 1962 to install crankcase controls nationwide by 1964, he would ask Congress for legislation to require them. He rejected the AMA insistence that automotive air pollution and smog were peculiar to California, saying, “It’s a problem all over the United States, not just the cities, but in the suburbs and in the farm areas.”[67]

The AMA insisted to Ribicoff that it would take many more months of testing before PCV devices could be installed nationwide, making it impossible to do so before the 1964 model year.[68] In fact, automakers would have been able to go ahead later that same year if they had wanted to, and they could certainly have done so well before 1964. In a document dated September 25, 1961, Cadillac’s Bob Templin noted, “there is nothing to prevent our going to positive crankcase ventilation as standard equipment for 1963, if policy dictates it. Our lives will be less troubled, however, if we don’t do it.”[69] The following day, Samuel G. Johnson of the International Harvester Motor Truck Engineering Department wrote to William Sherman to say that International “is in position to comply with blowby devices on all motor truck models at any date deemed advisable by AMA.”[70]

Finally, on December 6, the AMA board of directors voted to install PCV systems on all new U.S. cars and trucks for the 1963 model year. The AMA announced this nonbinding resolution the same day. However, they downplayed the federal threats, misleadingly claiming that the decision was based on new technical advice of the Engineering Advisory Committee about the feasibility of PCV devices for general use.[71]

California and New York Demand Closed Systems

Although U.S. automakers began voluntarily installing positive crankcase ventilation on most cars and trucks for the 1963 model year, the AMA decision was not the end of the matter by any means.

In California, the Motor Vehicle Pollution Control Board became concerned by the end of 1962 about the limitations of open PCV systems. Systems controlled by manifold or crankcase vacuum worked best at idle or light throttle, when vacuum was strongest. Under heavy load, at or near full throttle, there was too little vacuum to provide adequate ventilation airflow, so excess blowby was vented to the atmosphere (usually through the oil filler cap) to avoid excessive crankcase pressure. Not only was this counterproductive for reducing total hydrocarbon emissions, venting crankcase vapor into the engine compartment rather than under the car meant that occupants were more likely to notice a rotten-eggs smell due to the sulfur content of the blowby gases.

At its meeting on December 18, 1962, the Motor Vehicle Pollution Control Board proposed a revision to the crankcase device certification regulations, adding the stipulation that “Installation of such device shall not create or contribute to a noxious or toxic effect in the ambient air.”[72] This effectively required the use of closed PCV systems that would route crankcase vapor back into the engine under all operating conditions.

The proposed regulation alarmed AMA representative George Delaney, who knew that New York state health officials were also preparing to issue a crankcase emissions rule for that state, and would likely make the same demands as California. Delaney registered such strenuous objections to the proposed rule that the AMA opted to boycott the subsequent board meeting on January 17, 1963. This was another miscalculation, as the revised regulation was approved with little further debate.[73] Since the board had also approved two “combination” systems that already met the requirements of the new rule, closed positive crankcase ventilation would become mandatory on most new cars and trucks sold in California beginning in January 1964.

Even so, the AMA Engineering Advisory Committee was still not prepared to accept this requirement. On March 1, 1963, the EAC reiterated that “the industry definitely does not want to be forced into putting the new systems on New York cars for 1963 and 1964.” GM Engineering VP Charles Chayne, acting as chair of the EAC, again asked member companies to supply technical arguments why it would be infeasible to install closed systems on all models for 1964.[74]

Chrysler, which had been prepared to go forward with closed positive crankcase ventilation from the start of 1964 model year production, relented later that month. In an interoffice memo on March 28, Chayne’s successor, new Engineering VP Harry F. Barr, noted:

I have recently had a call from Mr. Paul Ackerman of Chrysler which indicates they are pulling back their 1964 start of production releases and will release [closed systems] later, effective January 1, 1964, if required at that time by the California law. We are, of course, all hopeful that this will be further extended to start of production of 1965 models before time for this action arrives.

Barr added:

It is therefore quite important that no General Motors Division make any changes in their 1963 releases for start of 1964 model year production. Since changes would jeopardize the industry pollution that is being taken with the Air Pollution Board [sic] of California.[75]

None of this deterred the Air Pollution Control Board of the State of New York Department of Health, which issued a regulation requiring an approved crankcase ventilation system for every motor vehicle “manufactured or assembled after June 30, 1963, and registered in the State.”[76] The resolution allowed for exemptions for “any class or type of motor vehicle for which no practical control systems have been developed or necessary.” The New York certification criteria, finalized on March 22, were framed somewhat differently than the California rules, but also effectively required closed PCV systems.[77]

Despite the industry’s stalling and excuses, neither California nor New York officials proved amenable to further delays. However, as late as April of that year, the AMA still hoped to find excuses to drag their feet for a little while longer. In an April 29, 1963 letter to AMC VP of engineering and research Ralph H. Isbrandt, AMC engineer Robert T. Van Derveer, a member of the Vehicle Combustion Products committee, warned:

[F]or our 1964 production we have no other choice but comply with New York’s criteria by either the procedure just outlined or by installing the ‘closed’ system hardware that is released for California production commencing January 2, 1964. However, if we release the ’64 California ‘fiz’ [sic] for car one 1964 New York State production, we will run afoul of the A.M.A. policy on this matter, and as you are aware various industry representatives feel quite strongly that industry solidarity is a must on this matter.[78] [Emphasis added.]

Even when the AMA had reluctantly conceded that closed PCV systems would be required in California and New York for 1964 and beyond, the auto industry still refused to voluntarily standardize the higher-capacity closed systems nationwide. Instead, most 1963 and later cars and trucks continued to use open systems, with closed systems again treated as extra-cost mandatory options (typically priced between $5 and $7) in states that required them.

As if to underscore the ongoing need for regulatory requirements, in 1964, Ford actually deleted positive crankcase ventilation systems entirely for most models, reverting to a breather/road draft tube system except on the Ford Thunderbird, Lincoln Continental, and cars sold in California or New York.[79] Positive crankcase ventilation was restored to other models by the start of the 1966 model year, but Ford still used an open system except where otherwise required by state law.[80]

It was true that the use of closed positive crankcase ventilation systems involved certain trade-offs. For instance, returning excess blowby to the air cleaner had the effect of enriching the air-fuel mixture, which in turn could raise carbon monoxide emissions, and it also tended to increase throttle-body deposits.[81] Eventually, most of these issues would be mitigated by design improvements, although PCV systems still required periodic maintenance to keep the valve and hoses from plugging. However, the auto industry’s reticence was driven far less by any legitimate technical concern than by sheer intransigence and the AMA determination to delay compliance with any regulatory requirement for as long as possible.

Federal Crankcase Emissions Standards

By 1965, concern about automotive air pollution had become a national issue, despite the continued insistence of the auto industry and its apologists that smog wasn’t a concern outside of certain parts of California. In January 1965, Sen. Edmund S. Muskie (D–Maine) introduced Senate Bill 306 to establish a statutory framework for federal motor vehicle emissions standards. It passed the Senate in May and the House in September. President Lyndon B. Johnson signed the bill, now called the Motor Vehicle Air Pollution Control Act, on October 20, 1965 (Public Law 89–272).[82]

This law amended the Clean Air Act to provide for the establishment of national standards “applicable to the emission of any kind of substance, from any class or classes of new motor vehicles or new motor vehicle engines, which … contribute to, or are likely to cause or to contribute to, air pollution which endangers the health or welfare of any persons.” The Motor Vehicle Air Pollution Control Act delegated establishment of the actual standards and their effective dates to the secretary of Health, Education, and Welfare, who at that time was John W. Gardner. Although Abe Ribicoff had left that office in 1962 to run for the U.S. Senate (he was succeeded through August 1965 by Anthony J. Celebrezze), the new law effectively made good on Ribicoff’s threat of four years earlier.

HEW published the final version of its initial auto emissions standards in the Federal Register on March 30, 1966, effective for the 1968 model year.[83] In addition to exhaust standards for most new cars and trucks sold in the U.S., the federal regulations included a standard for crankcase emissions.[84] This requirement was actually stricter than those of California or New York: “No crankcase emissions shall be discharged into the ambient atmosphere from any new motor vehicle or new motor vehicle engine.” It stipulated that vehicles subject to the standard continue to comply “for not less than 1 year after sale and delivery to the ultimate purchaser.”

The federal standard finally, belatedly, ended the debate about when or if closed PCV systems would be adopted for all U.S. cars and trucks.

Ironically, in a 1968 SAE paper, GM Engineering Staff emission control engineer Fred W. Bowditch blandly stated that that crankcase emissions were “responsible for around another 20% of the total hydrocarbon emissions to the atmosphere”[85] — only about half what GM had briefly claimed back in 1960.

Little came of the 1969 federal lawsuit against the auto industry. Only months after filing the suit, the Nixon administration agreed to settle it with a consent decree in which the defendants agreed to end their cooperative program on emissions without admitting any wrongdoing.[86] The U.S. Supreme Court later dismissed all state lawsuits related to the matter.[87]

Global Standards

Other countries subsequently established their own crankcase standards. The 1969 second edition of the Australian Design Rules for new motor vehicles required crankcase emissions controls, although this requirement took effect on different dates in each state and territory, generally between January 1, 1970, and January 1, 1972.[88] In Japan, crankcase emissions controls for gasoline-powered cars and trucks sold in the home market were required beginning in September 1970.[89]

The first European-market requirements for crankcase emissions of spark-ignition engines were established by UN Economic Commission for Europe (ECE) Regulation No. 15, first registered August 1, 1970. Because the treaty required contracting parties to accede to proposed regulations individually, different European countries did so at different times: France and Spain were first, in August 1970, followed by Belgium and Italy later in the year. Other countries followed on an irregular basis over the next decade.[90] Under this regulation, type approval for new spark-ignition vehicles required three emissions tests, one of which (the Type-III test) limited crankcase hydrocarbon emissions to “less than 0.15 per cent of the mass of the fuel consumed by the engine,”[91] the same as the 1960 California standard. (Modern Euro emissions standards are stricter than the ECE 015 rules.)

In November 1970, Canada’s Ministry of Transport introduced a standard similar to the U.S. requirement as part of the emissions regulations under the Motor Vehicle Safety Act, effective January 1, 1971.[92]

Most countries now have crankcase emissions regulations, although some didn’t adopt similar standards until the 1980s or later, and there are still regional variations in the requirements for engines designed to run on fuels other than gasoline. However, in most countries outside the U.S., crankcase standards have usually been among the earliest emissions regulations adopted.

Doing Things the Hard Way

There’s no question that crankcase emissions controls provide a modest but useful reduction in total hydrocarbon emissions, and because the technology was cheap and well-understood even in the early sixties, its adoption was low-hanging fruit in the battle against smog. That the U.S. auto industry added positive crankcase ventilation voluntarily would have been commendable if the AMA actions had not been mired in stubborn bad faith and outright collusion. (The DOJ memorandum makes clear how much pressure the AMA exerted on member companies to not break ranks, even where that threatened to put automakers in direct conflict with state law.)

The irony was that the only reason there was a political push for the universal adoption of positive crankcase ventilation at all was that the AMA, and principally GM, had so strenuously emphasized the benefits. If the AMA had not been so determined to derail the enactment of California’s exhaust standards, the state likely would have looked at crankcase emissions eventually, but, as with evaporative emissions controls, any actual requirement might not have taken effect until the seventies. (The California evaporative standard didn’t take effect until 1970, with the federal standard effective for 1971.)

In short, the industry had backed itself into a corner: It had first insisted, loudly, that crankcase controls were effective, cheap, and easy to add in production, only to spend the next three years arguing, loudly, that installing them universally would be difficult, costly, and ineffectual.

Back in the late fifties, automakers had experimented with devices intended to eliminate the hydrocarbon emissions spike that otherwise occurred when decelerating on a closed throttle.[93] However, when prototypes of some of these devices were demonstrated in 1957 to Los Angeles County officials, the county’s Air Pollution Control District agreed that the reduction wasn’t worth the cost.[94] To the extent that uncontrolled crankcase blowby can be generalized, the actual HC reduction provided by positive crankcase ventilation was probably even less than those devices — perhaps 20 to 25 percent. A 20 percent reduction for only $10 (about $107 in 2025 dollars) was still worthwhile, but it didn’t meaningfully change the need to control exhaust emissions. (Even the 80 percent reduction in exhaust hydrocarbon emissions specified by the original California emissions standards proved to be woefully inadequate.)

Of course, reduced hydrocarbon emissions were only one of the benefits of widespread adoption of positive crankcase ventilation. It still reduces combustion byproducts, moisture, and other contaminants from the crankcase, which has probably contributed in a small but significant way to the longer lifespans of modern engines.

At the end of the day, however, the saga of crankcase ventilation and crankcase emissions was far less about the technical particulars than about attitude: the auto industry’s intense resistance to any external regulation and their determination to do only the bare minimum, even when it cost them more in the long run.

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End Notes

1. Wilfred W. Lowther, Donaldson Co., “Crankcase Ventilation and Sludge,” SAE Technical Paper 370104, April 21–23, 1937. doi:10.4271/370104
2. U.S. Navy, Bureau of Ships, Diesel Engine Maintenance Training Manual (Washington, D.C.: U.S. Government Printing Office, February 1946): 23.
3. Lee Vinsel, Moving Violations: Automobiles, Experts, and Regulations in the United States (Baltimore, Md.: Johns Hopkins University Press, 2019): 165.
4. “A Suggested Remedy for Crankcase Distribution,” Automotive Industries Vol. 41, No. 17 (October 23, 1919): 834.
5. Ivan L. Anderson, University of Utah, Salt Lake City, “A Possible Solution of the Crankcase-Oil Dilution Problem,” SAE Journal Vol. 15, No. 1 (July 1924): 43–46.
6. “The New Viking,” The Accessory and Garage Journal Vol. 18, No. 11 (April 1929): 18–21.
7. “New White Light Duty Six Truck,” The Accessory and Garage Journal Vol. 19, No. 2 (July 1929): 38.
8. Charles E. Smith, Ethyl Corporation, “Crankcase Ventilation,” SAE Technical Paper 450145, October 12, 1945. doi:10.4271/450145
9. U.S. War Department, Technical Manual No. 9-802: Truck, Amphibian, 2½-Ton, 6×6 (Washington, D.C.: U.S. War Department, October 15, 1942): 255–257.
10. Charles E. Smith, Ethyl Corporation, “Crankcase Ventilation,” SAE Technical Paper 450145, October 12, 1945. doi:10.4271/450145
11. Fram Corporation advertisement for Positive Crankcase Ventilator, Popular Science Vol. 150, No. 3 (March 1950): 266.
12. Hartley E. Howe, “All About Russian Cars,” Popular Science Vol. 159, No.4 (October 1951): 106–111, 302.
13. William Carroll, “Russian Cars Evaluated,” SAE Journal Vol. 67, No. 8 (August 1959): 26–37.
14. B. Gratz Brown, Ford Motor Company, “Taking the Guesswork Out of Crankcase Ventilation,” SAE Transactions Vol. 3, No. 1 (January 1949): 18–25. doi:10.4271/490174
15. Gerhardt C. Hass and John R. Scanlin, California Motor Vehicle Pollution Control Board, “The Control of Crankcase Hydrocarbon Losses,” SAE Technical Paper 630425, August 19–22, 1963. doi:10.4271/630425
16. Jack Q. Payne and Harrison W. Sigworth, California Research Corporation, “The Composition and Nature of Blowby and Exhaust Gases from Passenger-Car Engines,” Proceedings of the Second National Air Pollution Symposium (Los Angeles: National Air Pollution Symposium, 1952): 62–70.
17. Gilbert Way, Ethyl Corporation, and Walter S. Fagley Jr., Engineering Staff, Chrysler Corporation, “Field Survey of Exhaust Gas Composition,” SAE Technical Paper No. 11A, January 1958, reprinted in Vehicle Emissions — Part I (Selected SAE Papers 1955–1962) (New York: Society of Automotive Engineers, 1972): 102–120.
18. William L. Faith, Air Pollution Control (New York: John Wiley and Sons, 1959).
19. Fred L. Hartley, Charles C. Moore, and James B. Gregory, Union Research Center, Union Oil Co. of California, “The Smogless Auto,” Journal of the Air Pollution Control Association Vol. 10, No. 2 (April 1960): 143–146. doi:10.1080/00022470.1960.10467913
20. Ch. 200, § 1. Ch. 835, § 1. [1959] Cal. Stats. Reg. Sess. 2091, 2885.
21. John A. Maga and Gerhardt C. Hass, California Department of Public Health, “The Development of Motor Vehicle Exhaust Emission Standards in California,” Journal of the Air Pollution Control Association Vol. 10, No. 5 (October 1960): 393-414. doi:10.1080/00022470.1960.10467949
22. Paul A. Bennett, Chester K. Murphy, Marvin W. Jackson, and Richard A. Randall, General Motors Research Laboratories, “Reduction of Air Pollution by Control of Emissions from Automotive Crankcases,” SAE Transactions Vol. 68 (1960): 514–536. doi:10.4271/600054
23. Quoted in Grand Jury (GJ) Ex. 583, Department of Justice (DOJ) memorandum, May 18, 1971, 117 Cong. Rec. 15627 (1971).
24. AMA Engineering Advisory Committee meeting minutes for Jan. 10, 1958, quoted in GJ Ex. 339, DOJ memorandum, 117 Cong. Rec. 15630 (1971).
25. Scott H. Dewey, “‘The Antitrust Case of the Century’: Kenneth F. Hahn and the Fight Against Smog,” Southern California Quarterly Vol. 81, No. 3 (Fall 1999): 341–376. Available at SSRN: https://ssrn.com/abstract=1762770
26. Congressional Record — House of Representatives, “Smog Control Antitrust Case,” Tuesday, May 18, 1971, 117 Cong. Rec. 15626–15637 (1971).
27. GJ Ex. 384, DOJ memorandum, 117 Cong. Rec. 15630 (1971).
28. DOJ memorandum, 117 Cong. Rec. 15629–15630 (1971).
29. Robert J. Templin, Cadillac Motor Car Division of General Motors Corp., interoffice memorandum to John H. Lamb, October 6, 1959, quoted in GJ Ex. 499, DOJ memorandum, 117 Cong. Rec. 15630 (1971).
30. AMA Engineering Advisory Committee report, Dec. 3, 1962, quoted in GJ Ex. 345, DOJ memorandum, 117 Cong. Rec. 15630 (1971).
31. Discussion section of Bennett et al (1960), “Numerous Research Programs Are Underway on Air Pollution,” SAE Transactions Vol. 68 (1960): 528. doi:10.4271/600054
32. Discussion section of Bennett et al (1960), “Internal Breather Systems One Answer to Problem,” SAE Transactions Vol. 68 (1960): 532–534. doi:10.4271/600054
33. “Brown Hedges on Smog Session of Legislature,” Los Angeles Times, November 3, 1959: B2.
34. “New Standards for Cars Weighed by State in Fight Against Smog,” Los Angeles Times, November 7, 1959: B1.
35. Quoted in GJ Ex. 555, DOJ memorandum, 117 Cong. Rec. 15629–15630 (1971).
36. “New Way to Combat Auto Smog Described,” Los Angeles Times, December 1, 1959: B7.
37. “Inexpensive Anti-Smog Device to Be Offered on Cars Next Year,” New York Times, December 6, 1959: 67.
38. Associated Press, “Smog Device to Be Added to New Cars,” Lakeland Ledger [Lakeland, Fla.], May 2, 1960: 19.
39. Robert L. Chass, Philip S. Tow, Robert G. Lunche, and Norman R. Shaffer, L.A. County Air Pollution Control District, “Total Air Pollution Emissions in Los Angeles County,” Journal of the Air Pollution Control Association Vol. 10, No. 5 (October 1960): 351. doi:10.1080/00022470.1960.10467943
40. “Brown Hedges on Smog Session of Legislature,” Los Angeles Times, November 3, 1959: B2.
41. Robert Blanchard, “Legislative Session on Smog Billed,” Los Angeles Times, January 6, 1960: 2.
42. Associated Press, “GM Experts Describe Devices to Curb Smog,” Los Angeles Times, January 16, 1960: 18.
43. Paul A. Bennett, Chester K. Murphy, Marvin W. Jackson, and Richard A. Randall, General Motors Research Laboratories, “Reduction of Air Pollution by Control of Emissions from Automotive Crankcases,” SAE Transactions Vol. 68 (1960): 514–536. doi:10.4271/600054
44. Discussion section of Bennett et al (1960), “Blowby Gases Contribute to Smog Potential,” SAE Transactions Vol. 68 (1960): 529–530. doi:10.4271/600054
45. Robert K. Stone, Kenneth L. Kipp, and J. Harkins, California Research Corporation, discussion section of Bennett et al (1960), “Blowby Gases Cause 20–25% of Engine Hydrocarbon Emissions,” SAE Transactions Vol. 68 (1960): 531–532. doi:10.4271/600054
46. Discussion section of Bennett et al (1960), “Blowby Is Source of Atmospheric Olefins,” SAE Transactions Vol. 68 (1960): 532. doi:10.4271/600054
47. Ch. 23. § 1, [1960] Cal. Stats. 1st Ex. Sess. 346.
48. Ch. 36. §1, [1960] Cal. Stats. 1st Ex. Sess. 380.
49. State of California, Department of Public Health, Technical Report of California Standards for Ambient Air Quality and Motor Vehicle Exhaust (Berkeley, Calif.: California Department of Public Health, 1960): 107.
50. State of California, Motor Vehicle Pollution Control Board, Report to Governor Edmund G. Brown and the Legislature (N.p.: Motor Vehicle Pollution Control Board, Jan. 12, 1961): 12.
51. Diana Clarkson and John T. Middleton, California Motor Vehicle Pollution Control Board, “The California Control Program for Motor Vehicle Created Air Pollution,” Journal of the Air Pollution Control Association Vol. 12, No. 1 (January 1962): 22–28. doi:10.1080/00022470.1962.10468042
52. Donald A. Jensen, Air Pollution Control Association TA-10 Vehicular Exhaust Committee, “Crankcase Emission Control Devices for Typical Gasoline Engines: Informative Report No. 1,” Journal of the Air Pollution Control Association Vol. 13, No. 4 (April 1963): 173–174. doi:10.1080/00022470.1963.10468162
53. Gerhardt C. Hass and John R. Scanlin, California Motor Vehicle Pollution Control Board, “The Control of Crankcase Hydrocarbon Losses,” SAE Technical Paper 630425, August 19–22, 1963. doi:10.4271/630425
54. Donald A. Jensen, Air Pollution Control Association TA-10 Vehicular Exhaust Committee, “Crankcase Emission Control Devices for Typical Gasoline Engines: Informative Report No. 1,” Journal of the Air Pollution Control Association Vol. 13, No. 4 (April 1963): 173–174. doi:10.1080/00022470.1963.10468162
55. State of California, Motor Vehicle Pollution Control Board, Report to Governor Edmund G. Brown and the Legislature (N.p.: Motor Vehicle Pollution Control Board, January 12, 1961): 25.
56. Cal. Admin. Code, tit. 13, § 2003 et seq. (1961).
57. State of California, Motor Vehicle Pollution Control Board, Report to Governor Edmund G. Brown and the Legislature (N.p.: Motor Vehicle Pollution Control Board, January 7, 1963): 16–17.
58. Andrew H. Rose Jr. and Ralph C. Stahmen, Division of Engineering Services, U. S. Department of Health, Education, and Welfare, “The Role of Engine Blowby in Air Pollution,” Journal of the Air Pollution Control Association Vol. 11, No. 3 (March 1961): 114–144. doi:10.1080/00022470.1961.10467977
59. Morton Mintz, “Inexpensive, Simple: Auto Exhaust Device Reduces Air Pollution,” Washington Post, Feb. 1, 1960, and “Neuberger Wants Smog Device on All Autos,” Washington Post, February 14, 1960, both entered into the record as part of hearings of the House Committee on Interstate and Foreign Commerce in February 1960 and printed in Hearings Before a Subcommittee of the Committee on Interstate and Foreign Commerce, House of Representatives, Eighty-Sixth Congress, Second Session on Progress Being Made in Air Pollution Control, February 23 and 24, 1960 (Washington, D.C.: U.S. Government Printing Office, 1960).
60. “Bye, Bye, Blowby,” Washington Post and Times Herald, April 22, 1961, entered into the congressional record by Sen. Maurine B. Neuberger on April 27, 1961, 107 Cong. Rec. A2911 (1961).
61. James. M. Chandler, Ford Motor Company, memorandum, January 10, 1961, quoted in GJ Ex. 454, DOJ memorandum, 117 Cong. Rec. 15631 (1971).
62. GJ Ex. 360 and 442, DOJ memorandum, 117 Cong. Rec. 15631 (1971).
63. “Car Makers Told to Curb Exhausts,” New York Times, August 8, 1961: 31.
64. Sen. Maurine Neuberger, letter to 14 U.S. car and truck manufacturers, May 22, 1961, quoted in GJ Ex. 365, DOJ memorandum, 117 Cong. Rec. 15631 (1971).
65. William F. Sherman, AMA staff, memorandum for Engineering Advisory Committee of May 25, 1961, quoted in GJ Ex. 366, DOJ memorandum, 117 Cong. Rec. 15631 (1971).
66. GM internal document, June 1961, quoted in GJ Ex. 504, DOJ memorandum, 117 Cong. Rec. 15631 (1971).
67. “Car Makers Told to Curb Exhausts,” New York Times, August 8, 1961: 31.
68. “Car Makers Told to Curb Exhausts,” New York Times, August 8, 1961: 31.
69. Robert J. Templin, Cadillac Motor Division of General Motors Corporation, document dated September 25, 1961, quoted in GJ Ex. 509, DOJ memorandum, 117 Cong. Rec. 15631 (1971).
70. Samuel G. Johnson Jr., International Harvester, letter to William F. Sherman of AMA staff, September 26, 1961, quoted in GJ Ex. 364, DOJ memorandum, 117 Cong. Rec. 15631 (1971).
71. Bill Dredge, “Anti-Smog Devices for 1963 Cars Scheduled,” Los Angeles Times, December 7, 1961: B8.
72. Cal. Admin. Code, tit. 13, § 2003 (1962).
73. GM interoffice memorandum, January 24, 1963, quoted in GJ Ex. 376, DOJ memorandum, 117 Cong. Rec. 15632 (1971).
74. AMA Engineering Advisory Committee meeting transcript, quoted in GJ Ex. 507, DOJ memorandum, 117 Cong. Rec. 15632 (1971).
75. Harry F. Barr, GM Engineering Staff, interoffice memorandum, March 28, 1963, quoted in GJ Ex. 478, DOJ memorandum, 117 Cong. Rec. 15632 (1971).
76. Quoted in U.S. Department of Health, Education, and Welfare, Public Health Service, A Digest of State Air Pollution Laws, 1967 ed., Public Health Service Publication No. 711 (Washington, D.C.: U.S. Government Printing Office, 1967): 357.
77. Quoted in U.S. Department of Health, Education, and Welfare, Public Health Service, Bureau of Disease Prevention and Environmental Control, National Center for Air Pollution Control, A Compilation of Selected Air Pollution Emission Control Regulations and Ordinances, rev. ed. (Washington, D.C.: U.S. Government Printing Office, 1968): 122–124.
78. Robert T. Van Derveer, American Motors Corporation, letter to Ralph H. Isbrandt, April 29, 1963, quoted in GJ Ex. 558, DOJ memorandum, 117 Cong. Rec. 15632 (1971).
79. Roger Huntington, “More Smog Control = More Expense to the Driver,” Car Life Vol. 12, No. 7 (August 1965): 22–24. The deletion of the PCV system (except “as required by states”) is reflected in the 1965 AMA specifications for the Mustang, Fairlane, and full-size Ford.
80. Ford Motor Company, “AMA Specifications—Passenger Car,” full-size Ford cars, Form AMA-40A (Oct. 1, 1965): 8.
81. Gerhardt C. Hass and John R. Scanlin, California Motor Vehicle Pollution Control Board, “The Control of Crankcase Hydrocarbon Losses,” SAE Technical Paper 630425, August 19–22, 1963. doi:10.4271/630425
82. Legislative timeline per Congress.gov, https://www.congress.gov/bill/89th-congress/senate-bill/306/actions
83. 31 FR 5170–5178 (1966).
84. 45 CFR 85.10–12 (1966).
85. Fred W. Bowditch, General Motors Engineering Staff, “The Automobile and Air Pollution,” SAE Technical Paper 680242, 1968. doi:10.4271/680242
86. United States v. Automobile Manufacturers Association, 307 F. Supp. 617 (C.D. Cal. 1970).
87. Scott H. Dewey, “‘The Antitrust Case of the Century’: Kenneth F. Hahn and the Fight Against Smog,” Southern California Quarterly Vol. 81, No. 3 (Fall 1999): 341–376. Available at SSRN: https://ssrn.com/abstract=1762770
88. Australian Government, Department of Infrastructure, Transport, Regional Development, Communications, Sport, and the Arts, “Second Edition Australian Design Rules,” https://www.infrastructure.gov.au/infrastructure-transport-vehicles/vehicles/vehicle-design-regulation/australian-design-rules/second-edition.
89. Takuro Miyazaki and Toshiyuki Nishimoto, Ministry of Transport (Japan), “Motor Vehicle Emission Control Measures of Japan,” SAE Technical Paper 922178, October 19–22, 1992. doi:10.4271/922178
90. United Nations Treaty Collection, Chapter XI, Transport and Communications, B. Road Traffic, 15 United Nations Regulation No. 15, summary page at https://treaties.un.org/Pages/ViewDetails.aspx?src=IND&mtdsg_no=XI-B-16-15&chapter=11&clang=_en, as of May 18, 2025.
91. Agreement Concerning the Adoption of Uniform Conditions of Approval and Reciprocal Recognition of Approval for Motor Vehicle Equipment and Parts, Regulation No. 15, “Uniform Provisions Concerning the Approval of Vehicles Equipped With a Positive-Ignition Engine With Regard to the Emission of Gazeous Pollutions [sic] by the Engine,” (adopted August 1, 1970), 370 UNTS 740 art. 5.2.1.3. https://treaties.un.org/doc/Publication/UNTS/Volume%20740/v740.pdf
92. Government of Canada, Ministry of Transport, Motor Vehicle Safety Act: Motor Vehicle Safety Regulations, Schedule E, 1102, November 6, 1970, The Canada Gazette Part II, Vol. 104, No. 22 (November 25, 1970): 1245, 1320–1326.
93. Induction System Task Group, Automobile Manufacturers Association, “Automotive Exhaust Hydrocarbon Reduction During Deceleration by … Induction System Devices,” SAE Transactions Vol. 66 (1958): 383–396. doi:10.4271/580039
94. James M. Chandler, Test Engineering Section, Technical Service Department, Engineering Research and Advanced Product Study Office, Ford Motor Company Engineering Staff, letter to Kenneth Hahn, April 9, 1958, published in Kenneth Hahn, Supervisor, Second District, County of Los Angeles Board of Supervisors, A Factual Record of Correspondence Between Kenneth Hahn, Los Angeles County Supervisor, and the Presidents of General Motors, Ford, and Chrysler Regarding the Automobile Industry’s Obligation to Meet Its Rightful Responsibility in Controlling Air Pollution from Automobiles, February, 1963–January 1967 (Los Angeles: County of Los Angeles, 1967): nn.

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ACKNOWLEDGEMENTS

The author would like to thank the staff of the Los Angeles Public Library Science, Technology, & Patents Department for their invaluable assistance in accessing some of the now-ancient technical papers cited in these articles, and the staff of the California Air Resources Board CalEPA Library for providing us with a copy of the 1960 California Department of Public Health Technical Report of California Standards for Ambient Air Quality and Motor Vehicle Exhaust.

SUPPLEMENTAL READING

Because of the complexity of this article and our desire to document it as thoroughly as possible, we’ve opted to list our principal sources in the end notes rather than as a separate bibliography. Much of our larger bibliography on this subject is contained in the “Notes on Sources” section of our earlier article, Before the Muskie Act: Early Emissions Law and Regulation, 1940–1969.

For this article, we made a strenuous effort to draw as much as possible on primary and contemporary sources. However, there are several secondary sources we recommend for a fuller background:

• S. Kent Hoekman and J. Steve Welstand, “Vehicle Emissions and Air Quality: The Early Years (1940s–1950s),” Atmosphere Vol. 12, No. 10 (October 2021): 1354. doi:10.3390/atmos12101354 — This excellent 30-page paper offers an overview of the smog problem in California prior to the Rees-Richards Act of 1959, describing Arie J. Haagen-Smit’s research into the mechanisms of photochemical smog and the early studies that sought to establish the “baseline” emissions of cars without emissions controls.
• James E. Krier and Edmund Ursin, Pollution and Policy: A Case Study on California and Federal Experience with Motor Vehicle Air Pollution 1940–1975 (Berkeley and Los Angeles: University of California Press, 2019) — Originally published in 1977, this indispensable book offers a detailed, well-annotated account of the public and political history of auto emissions controls through the mid-1970s, although even at 400 pages, there are inevitably some points it skips over. The first chapter, “A Framework for the Problem,” is a bit of a slog, with more theory than history, but the remainder is quite readable for an academic text, and the book remains the single most useful non-technical resource we’ve yet found on this subject.
• Scott H. Dewey, “‘The Antitrust Case of the Century’: Kenneth F. Hahn and the Fight Against Smog,” Southern California Quarterly Vol. 81, No. 3 (Fall 1999): 341–376. Available at SSRN: https://ssrn.com/abstract=1762770 — This article provides a very good summation of the antitrust suit against the auto industry: how it came about and how it sputtered out, slamming the door on state and private action in the process.
• While the Dewey paper provides context on the antitrust investigation, we strongly recommend also reading the DOJ memorandum later released by Rep. Phillip Burton, which is contained in the Congressional Record for the House of Representatives for Tuesday, May 18, 1971 (117 Cong. Rec. 15594–1566). The memorandum begins on 15626 (page 33 of the PDF file), at the heading “Smog Control Antitrust Case,” and runs through 15637 (page 44 of the PDF file).

For a relatively straightforward technical introduction to early crankcase emissions controls, the EPA published a book on positive crankcase ventilation systems back in 1977, as the first of a series of nine educational texts on auto emissions controls. It was prepared by B.D. Hayes, M.T. Maness, R.A. Ragazzi, and R.A. Barrett of the Department of Industrial Sciences of Colorado State University, Fort Collins, and is entitled Motor Vehicle Emissions Control Book One: Positive Crankcase Ventilation Systems (Research Triangle Park, N.C.: U.S. Environmental Protection Agency, Office of Air and Waste Management, Office of Air Quality Planning and Standards, November 1977). Some of the PCV system illustrations in this article are from that book.