Over 46 years ago, General Motors took a significant step in response to high fuel prices and the demand for better fuel economy. The Oldsmobile diesel V8 was intended to mark a new era, but instead, it became a notorious failure that left a lasting impact on the reputation of diesel passenger cars. This article delves into the story of the Oldsmobile diesel, from its initial flop to the subsequent attempts at improvement and eventual abandonment.
GM: Forever Living In Infamy
It could be argued that those old-school diesels didn't deserve such a bad reputation. The Oldsmobile diesel V8 was indeed a blunder, yet GM managed to dominate the diesel car market and sell hundreds of thousands of units annually. However, sales don't always translate to happy customers.The engine's design flaws were numerous. The head bolts were overly stressed, leading to blown head gaskets or hydrolocking. Additionally, the lack of a water separator caused injector and internal corrosion. These issues were so severe that the Oldsmobile diesel V8 wasn't certified for sale in California.Customers like the Halfertys experienced firsthand the headaches of owning a faulty diesel car. They spent thousands of dollars on repairs and warranty work, leading to the formation of the Consumers Against General Motors group.Other problems included failing injectors, worn flat tappets, and leaky Stanadyne injection pumps. Despite these issues, people continued to buy Oldsmobile diesels, as GM held a significant market share in the early 1980s.Initial Failures and Design Flaws
Oldsmobile engineers based their work on the existing 350 cubic-inch V8, a decision that would come back to haunt them. Diesel engines typically have a higher compression ratio than gasoline engines, and the Oldsmobile diesel's design didn't account for this adequately. The reinforced block, hardened camshafts, and other changes were not enough to handle the high compression.The use of the same head bolts and 10-bolt pattern for both the diesel and gasoline engines was a cost-saving measure that proved to be a mistake. The head bolts couldn't handle the additional strain of the high-compression diesel design, resulting in frequent failures.Attempts at Improvement
In 1981, General Motors began to address the reliability issues of the Oldsmobile diesel V8. Engineers redesigned the heads, used stronger bolts, and changed the head gasket material. The injection pumps received new collars, and the glow plugs were improved. These upgraded engines, identified as "350 DX," showed significant improvements in reliability.MotorWeek reviews praised the quality improvements and good fuel economy of the Oldsmobile 98 Regency with the upgraded engine. However, it was too late. The original engine had been on the market for three years before the upgraded version was released, and buyers had already lost interest.In 1982, GM introduced two more diesel engines: the 4.3-liter Oldsmobile diesel V8 and the 4.3-liter Oldsmobile diesel V6. The 4.3-liter V6 was based on the 5.7-liter diesel V8 and shared many parts, but with a different firing order and crankshaft offsets.This time, it seemed that GM had learned its lesson. The 4.3-liter diesel V6 didn't have the catastrophic issues of the original 5.7-liter engines. It offered decent torque and fuel economy, with the Chevy Caprice Wagon getting up to 33 mpg on the highway.The End of an Era
By the mid-1980s, the diesel car market was facing challenges. The price of diesel fuel rose above premium gasoline, and people's focus shifted away from fuel economy. GM's reputation from the late 1970s also worked against it, and sales continued to slide.In 1984, stricter emissions regulations meant GM couldn't sell diesels in California. Finally, in 1985, GM gave up on its diesel passenger car program and wouldn't sell a diesel car to Americans again for nearly three decades.Today, diesel cars have largely faded from the American market, overshadowed by the rise of electric vehicles. It's hard to say what could have happened if GM had persevered with its diesel program, but it's clear that the company made a significant misstep along the way.