Oldsmobile produced three versions of a diesel engine between 1978 and 1985: a V8 in 1978-85, a V8 in 1979, and a V6 from 1982 until 1985. The engines powered front and rear-wheel drive vehicles; the 4.3-litre V6 was adapted to both transverse and inline front-wheel drive applications. Sales peaked in 1981 at approximately 310,000 units, which represented 60% of the total U.S. passenger vehicle diesel market. However, this success was short-lived as the V8 diesel engine suffered severe reliability issues. While Oldsmobile had appropriately strengthened the block, they left the head bolt design and pattern unchanged to enable them to use the same tooling as for the gasoline engines. Catastrophic head bolt failures were thus legion, as diesel engines have compression ratios that are as much as three times higher than a gasoline engine. The sales and reliability woes were compounded by a decline in gas prices as well as fuel quality issues including large volumes of diesel fuel containing water or foreign particles.
Failures
In addition to the head bolt issues, General Motors also decided not to install a water separator in order to cut costs. Low quality diesel fuel was a common problem at the time and most diesels were thus equipped to keep the injector pumps from corroding. Many owners tried to solve this by adding anhydrous alcohol, a common trick to deal with water in fuel, but this instead dissolved fuel pump seals and other parts. The stretchy fuel-pump timing chain was a minor problem in light of the other issues, but poor dealer service training only made all the problems worse. One Oldsmobile engineer who had worked on the project told his bosses not to release the hastily developed engine. General Motors, needing to meet upcoming CAFE standards forced him into early retirement and released the engine nonetheless. The Oldsmobile diesel's reputation for unreliability and anemic performance damaged the North American passenger diesel market for the next 30 years. Myriad lawsuits were filed as several grassroots groups formed to try to get General Motors to acknowledge the problem, made worse by simultaneous problems with GM's new THM200 automatic transmission. The California Air Resources Board had been unable to certify the diesel V8 for sale in the state in 1979 and early 1980, as the test cars issued to CARB broke down before the tests could be completed. Of the nine cars supplied to CARB, all suffered engine problems and seven had transmission failures. In 1980 the Federal Trade Commission filed a complaint which included the diesel engine issues and the transmission troubles as well camshaft issues with gasoline V8s. General Motors kept marketing the diesel to the fullest, with 19 of the 23 Oldsmobile models in 1981 being available with the 5.7 diesel. The later 4.3-liter V6 engine, which arrived for the 1982 model year, did not have the same problems as the V8. The V6 has a denser bolt pattern and Oldsmobile's engineers were given more time to develop and test it. General Motors also carried out several redesigns of the V8's heads, bolts, and various other parts, but by the time the engine was trouble-free the damage had already been done. While customer complains started dropping off after 1981, sales did too: diesels sold 43 percent less in 1982. The downward sales slide continued, not helped by stricter emissions standards - for the 1984 model year the Diesel V8 was no longer offered in California for that very reason. By 1985 the Oldsmobile Diesel engines were finally discontinued. A class action lawsuit eventually forced General Motors to pay up to 80 percent of the costs of new engines. Used car price guides have always indicated much lower prices for diesel-engined cars and they remain undesirable in the collector's market. A large number of cars simply had their broken diesels replaced with conventional gasoline engines. Although the engines were unreliable because of the head and problems with the ancillaries, the Oldsmobile diesels' strong blocks continue to see use in gasoline-powered race engines.
LF9
The LF9 is a diesel V8 produced from 1978 to 1985. Earlier versions and those used in pickups produced and torque, while later versions produced and torque. Applications:
The LT6 is 4.3-liter V6 produced from 1982 to 1984 and installed in rear-wheel drive vehicles. Power was rated at at 3600 rpm and at 1600 rpm. Applications:
The LT7 is a transversely-mounted version of the 4.3-liter V6 produced from 1982 to 1985. Power was rated at at 3600 rpm and at 1600 rpm. Applications:
