Oldsmobile Diesel V6 engine
Encyclopedia
Oldsmobile
developed three diesel engine
s for the 1980s: two V8s
and a 263 CID (4.3 L) V6. It was based on the Olds 350 V8 with a 4.057 in (103 mm) bore and 3.385 in (86 mm) stroke.
The history of passenger-car diesel engine
s at General Motors has been checkered. In the 1970s, the company was unable to power its large cars and trucks with their emissions-strangled engines. Like many other companies, GM turned to diesel power, directing the Oldsmobile
division to develop one V6 and two V8 to be shared with all divisions.
Oldsmobile's engines, the 5.7 L LF9 and 4.3 L LF7 V8s and the 4.3 L V6, were notoriously unreliable. Conversely the Oldsmobile engineers claimed that management proposed a time line for implementation that didn't accommodate enough testing. Although over one million were sold from 1978–1985, the failure rate of early GM diesel engines ruined the reputation of diesel engines in general in the United States market. Eventually, a class action
lawsuit resulted in an arbitration system under the supervision of the Federal Trade Commission
where consumers could claim 80% of the original cost of the engine in the event of a failure.
The primary problem with GM's diesel engines of the 1970s was their design - weakness in the head design and head bolts, which were not able to withstand the higher cylinder pressures and temperatures of diesel use. This design weakness combined with poor diesel fuel quality in the 80's led to catastrophic failure of pistons, cylinder heads, and even cylinder walls. Reinforced truck diesel engines, from GM and other companies, did not have these problems. Today, GM uses diesel engines from DMAX (for trucks) and Isuzu
(for non-US cars) but does not offer a diesel engine in any of their North American passenger cars.
High strength aftermarket head bolt sets are now available to make the engine more reliable in this area.
Water will rust the steel internals of the fuel system. Rust will damage the precision parts in diesel fuel injection pumps and high pressure diesel injectors causing erratic operation. Injecting fuel too much prior to TDC on the compression stroke will cause pressure conditions similar to pre-ignition/detonation in gasoline engines. Water in varying amounts will also be injected with the fuel charge. Any rust in the steel fuel lines, fuel filter, pump etc can damage replacement parts and continue to cause injection cycles out of time.
The above mix of conditions originating with water in the fuel can combine to create extreme cylinder pressures far exceeding those foreseen by GM engineers damaging the head gasket and sometimes breaking head bolts.
A head gasket leak effectively quenches ignition in the affected cylinder. This allows unburnt fuel and coolant to leak into the crankcase thinning the lubricating oil. It also combines with combustion byproducts to make mild acids that will attack the copper/babbitt bearings and aluminum pistons. A head gasket failure can be particularly damaging in a diesel. A diesel engine has effectively zero piston to head clearance at TDC on the compression stroke. The introduction of coolant into the cylinders can cause hydrolock. Hydrolock typically results in bent/broken crankshafts, pulled threads on main bolts, and bent connecting rods, effectively destroying an engine.
Because the various failures these engines encountered were causally interrelated, and dealership technicians were unfamiliar at best with passenger car diesel engines, recurrent failures were possible because only the most obvious symptoms of trouble were addressed. The "one use only" head bolts were commonly re-used and symptoms in other interrelated systems ignored. Thus, cars could suffer multiple head gasket/head bolt failures from re-use of head bolts or a damaged injection system.
The Oldsmobile Diesel V6 engines were produced on different tooling than their V8 counterparts. They received a head bolt pattern that is arguably a superior design capable of withstanding more consumer abuse.
produced from 1982-1984. Power was rated at 85 bhp @ 3600 rpm and 165 lb. ft. torque @ 1600 rpm
Applications:
diesel engine
produced from 1982-1985. Power was rated at 85 bhp @ 3600 rpm and 165 lb. ft. torque @ 1600 rpm
Applications:
Applications:
Oldsmobile
Oldsmobile was a brand of American automobile produced for most of its existence by General Motors. It was founded by Ransom E. Olds in 1897. In its 107-year history, it produced 35.2 million cars, including at least 14 million built at its Lansing, Michigan factory...
developed three diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
s for the 1980s: two V8s
Oldsmobile V8 engine
The Oldsmobile Rocket V8 was the first post-war OHV V8 at General Motors. Production started in 1949, with a new generation introduced in 1964. Like Pontiac, Olds continued building its own V8 engine family for decades, finally adopting the corporate Chevrolet 350 small-block and Cadillac Northstar...
and a 263 CID (4.3 L) V6. It was based on the Olds 350 V8 with a 4.057 in (103 mm) bore and 3.385 in (86 mm) stroke.
The history of passenger-car diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
s at General Motors has been checkered. In the 1970s, the company was unable to power its large cars and trucks with their emissions-strangled engines. Like many other companies, GM turned to diesel power, directing the Oldsmobile
Oldsmobile
Oldsmobile was a brand of American automobile produced for most of its existence by General Motors. It was founded by Ransom E. Olds in 1897. In its 107-year history, it produced 35.2 million cars, including at least 14 million built at its Lansing, Michigan factory...
division to develop one V6 and two V8 to be shared with all divisions.
Oldsmobile's engines, the 5.7 L LF9 and 4.3 L LF7 V8s and the 4.3 L V6, were notoriously unreliable. Conversely the Oldsmobile engineers claimed that management proposed a time line for implementation that didn't accommodate enough testing. Although over one million were sold from 1978–1985, the failure rate of early GM diesel engines ruined the reputation of diesel engines in general in the United States market. Eventually, a class action
Class action
In law, a class action, a class suit, or a representative action is a form of lawsuit in which a large group of people collectively bring a claim to court and/or in which a class of defendants is being sued...
lawsuit resulted in an arbitration system under the supervision of the Federal Trade Commission
Federal Trade Commission
The Federal Trade Commission is an independent agency of the United States government, established in 1914 by the Federal Trade Commission Act...
where consumers could claim 80% of the original cost of the engine in the event of a failure.
The primary problem with GM's diesel engines of the 1970s was their design - weakness in the head design and head bolts, which were not able to withstand the higher cylinder pressures and temperatures of diesel use. This design weakness combined with poor diesel fuel quality in the 80's led to catastrophic failure of pistons, cylinder heads, and even cylinder walls. Reinforced truck diesel engines, from GM and other companies, did not have these problems. Today, GM uses diesel engines from DMAX (for trucks) and Isuzu
Isuzu
, is a Japanese car, commercial vehicle and heavy truck manufacturing company, headquartered in Tokyo. In 2005, Isuzu became the world's largest manufacturer of medium to heavy duty trucks. It has assembly and manufacturing plants in the Japanese city of Fujisawa, as well as in the prefectures...
(for non-US cars) but does not offer a diesel engine in any of their North American passenger cars.
Head bolts
GM used "torque to yield", commonly known as "stretch" or "angle torque", head bolts. This allowed the bolt pattern to remain the same as the gas powered counterpart with an increase in clamping load when compared to standard head bolts. A total of 10 bolts per head were used. Four per cylinder with the center three pairs shared. This permitted the use of the same tooling and reduced setup costs. This design did not provide adequate clamping force under the severe conditions these engines were subjected to. Overheating or excessive cylinder pressure can breach the seal of the head gasket and in severe cases break the bolts.High strength aftermarket head bolt sets are now available to make the engine more reliable in this area.
Pump timing
The Stanadyne injection pump was chain-driven. With normal use, the chain stretches and the pump delivers fuel too late. The pump timing could be adjusted to return to normal operation.Water in fuel
Arguably a major portion of the real problem would have been quite simple to avoid. A water separator was not part of the fuel system on these engines. Water-contaminated diesel fuel was quite common.Water will rust the steel internals of the fuel system. Rust will damage the precision parts in diesel fuel injection pumps and high pressure diesel injectors causing erratic operation. Injecting fuel too much prior to TDC on the compression stroke will cause pressure conditions similar to pre-ignition/detonation in gasoline engines. Water in varying amounts will also be injected with the fuel charge. Any rust in the steel fuel lines, fuel filter, pump etc can damage replacement parts and continue to cause injection cycles out of time.
Consumer-created fuel problems
Water in gasoline is dealt with by adding anhydrous alcohol [drygas] to the fuel. This does not work with diesel fuel. Ignorant consumers used drygas in their diesels to combat the water. Alcohol accelerates wear of the governor flex rings inside the early Stanadyne DB injection pumps. These pumps include an ignition advance mechanism based on pump housing fuel pressure. The housing pressure is affected by fuel return flow. Pieces of a damaged governor flex ring lodged in the fuel return check ball assembly. The sometimes intermittently blocked return line combined with a damaged governor caused erratic ignition timing. The flex ring governor was replaced, by Stanadyne in 1985, with a much improved Elastomer Insert Drive Governor Assembly commonly referred to as an EID. The EID is a service replacement part that eliminates the disintegrating flex ring.The above mix of conditions originating with water in the fuel can combine to create extreme cylinder pressures far exceeding those foreseen by GM engineers damaging the head gasket and sometimes breaking head bolts.
A head gasket leak effectively quenches ignition in the affected cylinder. This allows unburnt fuel and coolant to leak into the crankcase thinning the lubricating oil. It also combines with combustion byproducts to make mild acids that will attack the copper/babbitt bearings and aluminum pistons. A head gasket failure can be particularly damaging in a diesel. A diesel engine has effectively zero piston to head clearance at TDC on the compression stroke. The introduction of coolant into the cylinders can cause hydrolock. Hydrolock typically results in bent/broken crankshafts, pulled threads on main bolts, and bent connecting rods, effectively destroying an engine.
Because the various failures these engines encountered were causally interrelated, and dealership technicians were unfamiliar at best with passenger car diesel engines, recurrent failures were possible because only the most obvious symptoms of trouble were addressed. The "one use only" head bolts were commonly re-used and symptoms in other interrelated systems ignored. Thus, cars could suffer multiple head gasket/head bolt failures from re-use of head bolts or a damaged injection system.
The Oldsmobile Diesel V6 engines were produced on different tooling than their V8 counterparts. They received a head bolt pattern that is arguably a superior design capable of withstanding more consumer abuse.
LT6
The LT6 was a very rare diesel engineDiesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
produced from 1982-1984. Power was rated at 85 bhp @ 3600 rpm and 165 lb. ft. torque @ 1600 rpm
Applications:
- 1982–1984 Oldsmobile CutlassOldsmobile CutlassThe Oldsmobile Cutlass is a line of automobiles made by the Oldsmobile division of General Motors. The Cutlass began as a unibody compact car, but saw its greatest success as a body-on-frame intermediate car....
Supreme, Supreme Brougham, Calais - 1982–1984 Buick RegalBuick RegalThe Buick Regal is a mid-size car introduced by General Motors for the 1973 model year. North American production ended in 2004 and began again in 2011. For the 2011 model year, Buick re-introduced the Regal to the North American market, positioned as an upscale sport sedan...
LT7
The LT7 was a transversely-mountedTransverse engine
A transverse engine is an engine mounted in a vehicle so that the engine's crankshaft axis is perpendicular to the long axis of the vehicle. Many modern front wheel drive vehicles use this engine mounting configuration...
diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
produced from 1982-1985. Power was rated at 85 bhp @ 3600 rpm and 165 lb. ft. torque @ 1600 rpm
Applications:
- 1982–1985 Oldsmobile CutlassOldsmobile CutlassThe Oldsmobile Cutlass is a line of automobiles made by the Oldsmobile division of General Motors. The Cutlass began as a unibody compact car, but saw its greatest success as a body-on-frame intermediate car....
Ciera and Supreme - 1982–1985 Oldsmobile 98Oldsmobile 98The Oldsmobile 98 was a full-size automobile and the flagship model of the Oldsmobile division of General Motors. The name first appeared in 1941 and was used again after American consumer automobile production resumed post-World War II...
Regency - 1985 (Listed in options 1982–1985) Chevrolet CelebrityChevrolet CelebrityThe Chevrolet Celebrity is a mid-size car produced by the Chevrolet Division of General Motors . The Celebrity was introduced in 1981 for the 1982 model year. The Celebrity was the best-selling car in the United States in 1986...
- 1982–1985 Buick CenturyBuick CenturyBuick Century is the model name used by the Buick division of General Motors for a line of full-size performance vehicles from 1936 to 1942 and 1954 to 1958, and from 1973 to 2005 for a mid-size car....
LS2
The LS2 was a front wheel drive version produced for 1985 only.Applications:
- 1985 only: Oldsmobile 98, Buick Park Avenue, Cadillac DeVille