Automotive History: Oldsmobile Diesel V8 – GM’s Deadly Sin #34 – Premature Injeculation

In the late ’50s, GM’s Detroit Diesel Division’s “Million Miler” -71 diesel engine was so superior to the competition, resulting in such market dominance that GM was forced by an FTC consent decree to sell it to its competitors.

In the early ’80s, GM’s Oldsmobile Division’s passenger car diesel engines turned out to be such a disaster, the FTC had to step in and broker a massive compensation deal on behalf of millions of its angry buyers.

The 1950s were GM’s golden decade; the 1980s its living hell. And the Olds diesel sprayed plenty of fuel on those flames.

The 1973-1974 energy crisis shook the foundations of The Big Three’s business proposition, which was always tilted heavily to large cars. Detroit built small cars reluctantly, because the fat profit margins they had on big cars just weren’t there, if any at all. And realistically, most Americans weren’t going to be happy with the Pintos and Vegas they bought in the depths of 1974 once the OPEC oil taps were turned on again.

In response, in 1975 Congress passed the Energy Policy and Conservation Act, which resulted in CAFE (Corporate Average Fuel Economy), set to take effect in 1978. The initial 1978 target number was 18mpg, tightening up substantially to 27.5mpg in 1985. The energy crisis was becoming an existential crisis for GM.

The first order of business was to start an across the board downscale program, which would become to be the biggest corporate investment program to date. Every line was to be completely new, starting with the large B-C Body cars in 1977. Reduced weight and improved aerodynamics allowed the return of six cylinder engines and smaller V8s, with significantly improved EPA mileage numbers.

In the case of this 1977 Chevrolet, the six cylinder version’s EPA rating was a 33% improvement over a ’76 with the 350 V8, and the ’77 305 V8 version was rated 20% better. A good start, but GM knew that it would have to keep improving those numbers in coming years. That led to various programs to further reduce weight and improve aerodynamics with these B-C Bodies, as well as improved drive line efficiencies. One of those programs resulted in the 1981 Cadillac V8-6-4 engine, with cylinder deactivation. It turned out to be highly problematic, due mostly to its electronic control module being underdeveloped and unreliable.

Other programs included the expanded use of the Buick V6, and Chevrolet developing a 90 degree V6 derivative from its small block V8. And there were lighter and further downsized gas V8s, like the Pontiac 301 and 265, the Chevy 267, and the Olds 307.

But there was another avenue yet to explore: the diesel. And there were a number of compelling reasons.

GM had been keenly aware of the rapidly growing success of Mercedes, and that an increasing percentage of them were diesels. The fact that upscale buyers would gladly pay 2-3 times as much for a slow, sometimes smelly and sooty diesel compared to a big GM sedan must have been painful. A diesel Mercedes was the hot new status item for those that couldn’t quite swing a 450SE or SL.

Peugeot’s 504 diesel was hot too. Like Mercedes, Peugeot had a half century of experience in the field. And who the ad referring to?

And in 1976, VW jumped into the diesel market in a big way. The Golf/Rabbit’s diesel was a direct development (“conversion”) of its gas engine, and showed that it was not necessary to start from scratch in building a successful diesel engine. As such, it offers a counterpoint to the Olds diesel, both being converted gas engines. It resulted in an extremely economical yet surprisingly agile car, changing the image of a modern diesel. And it turned out to very durable. The Europeans appeared to be showing the way forward.

Rudolf Diesel’s namesake engine had a couple of very compelling qualities at the time. It needed no emission control systems, as it inherently had lower outputs of HC and CO, and NoX standards were still very generous at the time.  Gas engine emission systems were becoming more complex and expensive with each tightening of the EPA standards.

It intrinsically was more efficient than a gas engine, roughly 25-40% more so for a given displacement. In addition to the obvious benefits, this also resulted in significantly longer range between fill ups, another advantage at a time when memories of gas station waiting lines were still fresh.

And diesel fuel was still consistently cheaper than gasoline, as a result of the imbalance of demand, taxes, and as well as other factors.

Maintenance was potentially reduced, as there was no ignition system, emission system, carburetor, or complex electronic fuel injection system. Oil changes did require shorter intervals (typically 3,000 miles), and the oil capacity was usually greater. But the appeal of the diesel’s intrinsic simplicity was compelling.

So in 1975, Oldsmobile, long known as GM’s “experimental division”, began the development of a diesel engine. Before we go any further, let’s quickly address a common refrain: why didn’t GM give the job to Detroit Diesel, which had been building diesels since 1933?

For several good reasons. To start with, Detroit Diesel’s two stroke engines, initially developed by Charles Kettering at GM Labs in very large format,  operated quite differently, with its necessary expensive blower. They were also extremely noisy, due to being direct injection as well as being two-stroke engines, which made them sound as if they were running at twice their actual engine speed. All passenger car engines were then still indirect injection, as the violent percussion of direct injection had not yet been tamed.

I’ve seen the smallest of the DD’s, the 4-53, swapped into pickups, like this one in an International, but it’s not done for practical purposes. They are very heavy, loud and rough, and the two stroke design does not like lots of low rpm use. It was absolutely not suitable for passenger car use.

A more obvious choice might have been the GMC Truck division, which undertook a gas to diesel conversion of its 60 degree V6 engine, which first appeared in 1960. In 1964, the Toroflow diesel appeared, which used a strengthened version of the gas V6 block and internal components and of course a new cylinder head. It’s possible that the V6 was designed in the first place with an eye to an eventual diesel version. Regardless, the Toroflow, intended as a more affordable diesel for medium duty trucks and buses, ended up with a fairly mediocre reputation. Its power output was modest, and it just wasn’t quite up to the abuse it got over the long haul. Not a total failure or disaster, but certainly not a memorable engine family.

In any case, the Toroflow’s direct injection “toroidal flow” cylinder head design also was not applicable to passenger car use. Direct injection diesels were not adapted to passenger car engines until the end of the 1980s. Cylinder head/precombustion chamber design was really the key element to passenger car diesels then, other than making sure the engine was robust.

So the job fell to the Olds Engineers, who first started on it in 1975, according to one source. And the Olds 350 (5.7L) V8 engine was the starting point. Why? Why not? There’s actually no good argument for not starting with a well designed gas engine and modifying it to be a diesel. As a matter of fact, the legendary Mercedes OM621/615/616/617 SOHC four and five cylinder diesels built from 1955 until 1991 were very much based on their gas engine counterparts. I suppose more correctly, one might say they were developed simultaneously with the same architecture and some shared parts. The point is, successful diesel engines do not need to be designed from scratch or unique.

In a R&T article, Olds engineer R. James Benner is quoted as saying “there are no textbooks or papers that explain how to build a diesel”. Really? Maybe hire an experienced diesel engineering firm like Ricardo or Porsche? Or better yet, how about taking advantage of the deep diesel experience at affiliate Isuzu, of which GM owned 34% since 1972?

Isuzu had been building its compact precombustion chamber C-Series engines since 1959. A version of that venerable engine is still clattering away today in this 1982 Isuzu I-Mark diesel that I’ve been following for ten years. It just won’t die.

Let’s see: one version of the Isuzu C220 2.2 L four made 73 hp; if they had just doubled that up into a V8 it would have had 4.4 L and made some 145 hp, or 25-40 more than the Olds 5.7. And I’d still be shooting numerous legendary Olds Diesels clattering away hereabouts. Just how hard would that have been? I’m sure Isuzu would have been thrilled at the prospect. But the NIH (Not Invented Here) syndrome was extremely powerful at GM, a curiously deadly strain at that. Meanwhile, I’ve yet to find a genuine Olds diesel on the streets here in ten years, despite millions having been made.

Ironically, after somewhat mixed results with its later 6.2 and 6.5 diesel light truck V8s, GM finally did turn to Isuzu for the Duramax V8. And it’s compiled a generally excellent reputation over the years, certainly better than the Ford PowerStroke. Oh well.

Olds engineer Benner said they put together what seemed to be a proper diesel V8 and said “Let’s run it and see what falls apart first. That engine lasted about 30 minutes. So we built another, correcting the faults of the first, and ran that to see what would fall apart second, and on and on”.

That’s all good and well, if you’re going to start from scratch to reinvent the diesel. But the deadly problem is that development and durability testing was cut short, to satisfy the sales and marketing guys, as well as the bean counters. From a 1983 New York Times article:

Darrel R. Sand, a former G.M. engineer who helped design the Oldsmobile V-8 diesel engine, is not surprised. He said last week that he had strongly advised his superiors at the company against putting the engine into production back in 1977 and 1978, but he said that his objections were ignored because the company needed the fuel-efficient diesel in order to meet fuel economy standards for its fleet.

”In test after test, we had broken crank shafts, broken blocks, leaking head gaskets and fuel pump problems,” Mr. Sand said. ”The diesel couldn’t hold up, it was a hastily converted gasoline engine with a fuel pump designed for heavy trucks.”

In 1980, Mr. Sand said he was forced to retire for causing such a fuss about the diesel. G.M., however, would not comment on Mr. Sand’s charges.

But that doesn’t quite tell the whole story either.

Although the Olds 350 block was modified for diesel use, with larger bearing areas and such, and its internal components were strengthened, the critical issue was in the cylinder head studs. In order to maximize production efficiency and have the diesel block run down the same transfer line (milling, machining, drilling), the number of cylinder head studs was not increased from the 10 per side as can be seen on this gas 350 block. Diesel engines have compression ratios up to 3x that of gas engines, thus the forces acting on the heads wanting to separate them from the block are much greater. The resultant stretched head bolts caused leaking head gaskets, which allowed coolant into the combustion chamber, causing hydrolock and other severe maladies.

The failure to increase the number of studs was a deadly mistake, and one that wouldn’t have been properly fixed without quite considerable investment in new production equipment. GM did make a number of “fixes” to mitigate this issue, with modified heads, stronger bolts and different head gasket material, all of which helped to one degree or another, but by that time, the diesel’s reputation had already caught up to it. The improved DX block version that arrived in 1982 was beefed up in a number of ways, and was essentially what it should have been in the first place.

The 4.3 L V6 that came out in 1982 did have a denser head bolt arrangement, and did not suffer the catastrophic head sealing failures of the V8.

The second deadly sin was that Olds omitted a fuel/water separator, purely for penny-pinching purposes. This was a standard item on essentially all other diesel engines. Water in diesel fuel was more common then, and removing water in diesel fuel is critical, as water corrodes the delicate high pressure diesel fuel pumps, injectors and other components of the system. Owners made the innocent mistake of adding anhydrous alcohol (dry gas) that is commonly used with gas engines to remove water from fuel, but in a diesel it dissolved fuel pump and other component seals.

Another weak spot was a stretchy timing chain; after 30-50K miles or so, the timing chain slack that would cause the injection pump to gradually fire later and later causing the pinging and detonation problems that exacerbated the “lifting” of the head and the gasket separation.

Another area that was a major concern were the glow plugs. The original pencil injectors were prone to failure and would leak sometimes contaminating the tips of the plugs. Also, when one or more glow plugs failed, owners would ruin starters and even engines with continual starting and/or lack of proper warm up. The original Stanadyne injection pumps were fitted with a plastic collar that was problem to failure. It was later retrofitted with a steel collar.

The initial version had flat tappets. These wore excessively quickly, as did the camshaft lobes. That required going to roller lifters and properly hardened cams. Crankshaft and connecting rod failures were not uncommon, quite likely as a consequence of water getting into the fuel raising combustion pressure drastically.

Compounding its woes, the diesel V8 was teamed with the new and notoriously weak THM-200 automatic transmission. The diesel 5.7 was the largest engine used with this unit, and failures were rampant. The combination of the two created huge failure rates, and even kept the diesel from being certified in California for some time. From that same NYT article:

In 1979 and early 1980, G.M. couldn’t sell its new diesels in California because test cars kept breaking down during state-run emissions tests. Thomas C. Austin, who directed the state’s Air Resources Board at the time, said that seven of G.M.’s nine test vehicles had transmission failures and all nine had engine problems. Mr. Austin, now a consultant to Consumers Against G.M., said the number of problems were ”extraordinary.”

And of course GM dealers had no experience with diesels, and were overwhelmed by angry customers. A number of customers were offered the option of swapping in a gas 350, and it was not uncommon to see an Olds with the Diesel badge on the road without the tell-tale noise and sooty exhaust.

Meanwhile, use of the Olds diesel engine soon spread across the whole GM family, starting in 1979 with Cadillac. It even became the standard engine on the new 1980 Seville, GM’s most expensive passenger car. So much for “The Standard of the World”.

Apart from all of the Olds diesel’s obvious reliability shortcomings, there’s also some questions that haven’t been asked about its performance, efficiency and actual impact to GM’s CAFE numbers.

A 1978 Olds 88 with the 5.7 diesel showed the following percentage improvement over the various gas engine versions:

3.8L V6: 20%   260 V8: 14%   350 V8: 26%   403 V8: 50%

Given that the diesel’s performance and 15 second 0-60 time was roughly comparable to the V6 and 260 V8, improvements of 20% and 14% seem pretty small, considering its higher noise, odors and soot, and most of all its extra cost of some $700-$800, which amounted to more than 10% of an 88’s purchase price.

In 1985, using the EPA’s adjusted numbers for an 88 (18 city/27 highway/21 combined), the 5.7 L diesel had only a 17% improved combined number than the Olds 307 V8 (15/22/18), which also had considerably better performance than the 5.7 L diesel.

As a point of comparison, the VW diesel Rabbit’s EPA numbers were 41% higher than the same size gas engine, and the Mercedes’ 300SD’s numbers were 47% higher than the 380SE.

Not only does it appear that the Olds diesel was not as efficient as the other diesels on the market, it also lagged in power output. The 120hp version of the 5.7 V8 made .34 hp/ci; the 1980-up 105hp version made .30 hp/ci. The 4,3 V6 made .33 hp/ci. Yet the Mercedes non-turbo 4 and 5 cylinders made .48 hp/ci, and the Peugeot .49, and the VW even made .50.

Not only was the Olds diesel underdeveloped in terms of reliability, but also in terms of performance and efficiency.

The 5.7 V8 also made its way under the hood of Chevy and GMC 1/2 ton pickups, with a 125 hp rating. The tow ratings were reduced, which strongly suggests that GM was not very confident about its abilities to handle a heavy load.

In 1979, the very short-lived LF7 260 cubic inch (4.3 L) V8 diesel joined the party. It was essentially the same as the 5.7, but with smaller bores, and made a paltry 90 hp. It was gone after its introductory year. (Note: the EPA numbers on these ads are the old unadjusted numbers, significantly higher than those used in more recent years)

Then in 1982, after the 5.7 V8 was already becoming well known for its deadly ways, Olds released the new 4.3 L V6 diesel. Essentially a 5.7 minus two cylinders, its head bolt count was increased to avoid the V8’s issues. In fact, it seems to have been a mostly satisfactory engine; it just took Olds a couple of more years to get there. The V6 was made in both RWD and transverse FWD applications, and made 85 hp, due to tightening emission standards. The 5.7 LF9 also had its power reduced from 120 to 105 hp in its later years.

Similarly to the 5.7 diesel V8, comparing the 4.3 V6 diesels EPA numbers shows only a very modest 8% improvement over the 2.5 L “Iron Duke” gas four, which had comparable output, but was of course significantly cheaper to buy.

Much like when GM wouldn’t kill the Corvair in its last years to spite its critics, Olds kept making its diesels long after the bloom had turned to a nasty stink. The LS2 version of the 4.3 V6 came out in 1985, with aluminum heads, specifically for the new FWD C platform cars (Olds 98, Buick Electra, and Cadillac DeVille and Fleetwood). How many were actually sold is another question. It was another one-year only engine, and undoubtedly finding one now, or then, would be a genuine unicorn.

Even a V5 version was contemplated, as confirmed by this prototype at the R.E. Olds Museum, and written up here.  It was presumably intended for the N-Body cars. A four cylinder is also mentioned in some articles from the time.

At the end of the 1985 MY, the glow plugs on the Olds diesels were pulled, ending not only one of the worst chapters of GM’s deadly decade of the 1980’s, but also playing a huge role in killing the diesel boom that had infected America. That had resulted in diesels showing up in all sorts of cars, including a BMW diesel engine in Lincolns. Compounding this rapid death was the fact that diesel fuel had become more expensive than gasoline, and meanwhile gas engines were improving their efficiency.

No need to beat a dead horse any longer. Let’s just say that class action lawsuits of such epic proportions forced the FTC to step in and broker an arbitration deal through the Better Business Bureau, which resulted in payments up to 80% of the cost of a replacement engine, presumably a gas one if the customer wisely demanded that. But buyers still mostly got stung, as resale values plummeted, and nobody had any interest in keeping them going, except for a few die-hard fans.

There is a lingering question that might be worth pondering: what if the Olds diesel had turned out to be a great engine? What if it had been turbocharged, and put out a healthy 200+ hp along with massive torque? The EPA numbers wouldn’t have changed, but it could have been sold as a performance engine, a viable replacement for the big blocks of yore. Would it have ushered in a golden era of big American diesels? A counterpart to the performance era of the late ’60s?

On second thought, never mind. Even my imagination has limits.

All of GM’s Deadly Sins are accessible here