Oldsmobile Diesel engine

Oldsmobile produced three versions of a diesel engine between 1978 and 1985: a 350 cu in (5.7 L) V8 in 1978-85, a 261 cu in (4.3 L) V8 in 1979, and a 263 cu in (4.3 L) 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.[2] 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.[2] 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.[3]

Oldsmobile rocketlogo.png   Diesel
GM Olds' Diesel logo on a Buick.jpg
  • V6:
  • 262.55 cu in (4,302 cc)
  • V8:
  • 260.54 cu in (4,269 cc)
  • 350.06 cu in (5,736 cc)
Cylinder bore
  • 3 12 in (88.9 mm)[1]
  • 4.057 in (103.0 mm)[1]
Piston stroke3.385 in (86.0 mm)[1]
Block materialCast iron
Head materialCast iron
ValvetrainOverhead valve 2 valves x cyl.
Compression ratio22.5:1,[1] 21.6:1[1]
Fuel systemIndirect injection
Fuel typeDiesel
Oil systemWet sump
Cooling systemWater-cooled
Power output85–120 bhp (63–89 kW)
Torque output160–220 lb⋅ft (217–298 N⋅m)
SuccessorDetroit Diesel V8 engine


In addition to the head bolt issues, General Motors also decided not to install a water separator in order to cut costs.[2] 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.[2] 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.[4]

The Oldsmobile diesel's reputation for unreliability and anemic performance damaged the North American passenger diesel market for the next 30 years.[5][6] 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.[4] The California Air Resources Board (CARB) 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.[4] 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.[4] 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.[7]

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.[2] 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.[4] 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.[8] By 1985 the Oldsmobile Diesel engines were finally discontinued.[9] 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.[9] 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.[3][10]


The LF9 is a 350 cu in (5.7 L) diesel V8 produced from 1978 to 1985. Earlier versions and those used in pickups (1978-1981) produced 120 hp (89 kW) and 220 lb⋅ft (298 N⋅m) torque, while later versions produced 105 hp (78 kW) and 205 lb⋅ft (278 N⋅m) torque.



The short-lived LF7 is a 260 cu in (4.3 L) V8 putting out 90 hp (67 kW) and 160 lb⋅ft (217 N⋅m) torque.



1983 V6 experimental at the RE Olds Transportation Museum

The LT6 is 4.3-liter V6 produced from 1982 to 1984 and installed in rear-wheel drive vehicles. Power was rated at 85 bhp (63 kW) at 3600 rpm and 165 lb⋅ft (224 N⋅m) 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 85 bhp (63 kW) at 3600 rpm and 165 lb⋅ft (224 N⋅m) at 1600 rpm.



The LS2 4.3-liter V6 was produced only in 1985 and installed in front-wheel drive vehicles.


See alsoEdit


  1. ^ a b c d e "Oldsmobile Diesel Technical Magazine". Retrieved 20 Dec 2013.
  2. ^ a b c d e Wojdyla, Ben (2011-05-04). "The Top Automotive Engineering Failures: Oldsmobile Diesels". Popular Mechanics. Hearst Magazine Media, Inc. Archived from the original on 2016-06-12.
  3. ^ a b Fish, Randy (2014-08-23). "Better Off Dead". Archived from the original on 2015-02-12.
  4. ^ a b c d e Decourcy Hinds, Michael (1983-03-27). "The Saga of the G.M. Diesel: Lemons, Lawsuits and Soon an F.T.C. Decision". New York Times: 8.
  5. ^ "What's Hot". Archived from the original on 16 February 2012. Retrieved 11 Jan 2014.
  6. ^ "Technical: Diesel Redux". Retrieved 11 Jan 2014.
  7. ^ Chevedden, John; Kowalke, Ron (2012). Standard Catalog of Oldsmobile 1897–1997. Iola, WI: Krause Publications. p. 156. ISBN 978-1-4402-3235-0.
  8. ^ Chevedden and Kowalke, p. 168
  9. ^ a b Chevedden and Kowalke, p. 130
  10. ^ "Ghosts of Diesels Past: Failed cars from 20 years ago still haunt GM, U.S. market - Autoweek". Retrieved 11 Jan 2014.