3rd Oct 2007, 19:31

Long live the 350 diesel! I have owned 2 of these engines in cars and love them. The first was an '81 Buick Century purchased from the original old lady owner. She said the motor started slinging oil around 60,000 miles, so she had it replaced with a Goodwrench crate engine in 1986. By 1983 most of the bugs had been worked out of these engines, so that '86 motor ran great until I sold it with 190,000 miles on it and I believe it's still cruising around the area. Last time I saw it was a couple months ago.

Second is my '83 Oldsmobile Custom Cruiser wagon with the 350 diesel. She has 130,000 miles and the only thing I've ever had to do to it was replace a couple leaky injectors. Runs like a dream with plenty of power to tow my boat. Also gets 24-25 MPG. Not bad for a 4500 lb 17 foot long station wagon!!

Most people who bash the 350 diesels know next to nothing about them and are just parroting what they heard their elders say. I can't count the number of times I see someone talking about how they are "just a converted gas engine". NOT TRUE. They were designed off the Olds 350, but the block was build from the ground up as a diesel, with thicker mains etc. When was the last time you saw a 600 lb gas motor??

True, GM should have done much more R+D with this motor, but everyone has their bugs to work out in the beginning. The '78-79 D block engines were the worst. The head bolts used were not much bigger than the gas version, leading to blown gaskets and the main bearing bolts were not tapped deep enough into the block, resulting in broken maincaps and bearing housings. By 1981 they introduced the DX engine which was WAY better, with stronger bolts and deeper main threads.

15th Jan 2008, 21:54

Still have my '82 Ninety-Right 2 door diesel and it's still running great. Powerful, and runs all day. The longer I drive it, the more it wants to go. It's hard to park it sometimes. Basically all I do is fuel it and add Stanadyne treatment. It's just amazing the way this car performs after so many years with all original parts, as from the factory. Of course, I always let it warm up for 5-7 minutes before driving!

25th Aug 2008, 17:29

5 GM diesel vehicles, all with the 5.7 dx engines: 1979 Cutlass Cruiser, 1980 Cutlass LS, 1979 98 Regency, 1980 98 Regency, 1984 98 Regency Brougham.

All these vehicles run perfectly, even the 79 pencil engines. They are all driven regularly local and long distance.

I stockpile parts whenever I can to ensure continued service. One must remember these were concept engines developed 30 years ago with many still running.

As with anything, with proper maintenance and care, they are great. Abused and neglected, serviced by folks that know just enough to get into trouble, and yes you get a bag of worms.

GM celebrates 100 years; congrats and they must be doing something right.

15th Oct 2008, 14:49

The 5.7 diesel was not thought out as it should have been. There was much haste and shortcuts taken to get the motor to market, because diesel fuel was 80 cents below gas.

The motor had 2 major flaws: No water separator in the fuel system, and a mass production approach to assembly. Both were easily correctable by adding an after market water separator to the fuel system, and by proper sequence torquing the head bolts.

We were careless and bought diesel fuel at truck stops, and got water contaminated fuel, leading to many issues. After replacing the rusty injector pump with a rebuilt one, adding a water separator and purchasing fuel at pumps that had external filters, all major issue were solved.

I did find out later about the head bolts, but the engine suffered permanent damage from low oil when an oil cooler line broke while driving. Changed the oil in the engine every 3K and it was good to go.

Got about 18 MPG City/Highway on an Olds 98 4 door with a 28 Gallon tank. Went forever before fill ups.

10th Nov 2008, 17:12

The GM 4.3 V6 Diesel was a decent, stout engine. My dad bought a Chevy Celebrity station wagon new in 1984 and ordered it with that engine. It was a really good car for him. Did great in the snow with that heavy engine, got 30+mpg all the time and over 40mpg on highway trips. He also ran it on heating oil (red) its entire life. After about 15 years of this he had to have the injector pump rebuilt and a couple years later, the head gaskets replaced. Very gutsy engine! 85-90hp? Okay... but it had a lot more inherent torque than a comparable gas engine.

24th Dec 2008, 23:15

I'm thinking of getting a 1981 Olds 98 diesel as my first car. I've read some mixed messages, but overall it sounds like if properly maintained, these are decent, reliable cars, is this the case?

26th Dec 2008, 01:17

I wouldn't mess with an old diesel. The new Ultra low sulfur diesel, which will be the only on road kind of diesel available in 2010, is extemely hard on old diesel engines. It lacks the lubricity of the old fuel and will cause much harder wear. Diesel is almost $1 more per gallon right now than gasoline, and to top things off you would have to buy expensive additives just to keep that motor from destroying itself. These engines can deliver excellent MPG's when properly maintained, but finding parts for them is a chore in and of itself. If you really want a diesel, I would get an old Mercedes 200 series that has the vegetable oil conversion.

26th Dec 2008, 09:55

Excellent advice above. There are too many people out there whose "knowledge" of diesels is limited to what they have heard: they will get twice the mpg of a similar gas engine and they will run for 500K miles with practically no maintenance.

So they go out and find an old GM diesel selling for cheap, buy it and then get their rude awakening.

13th Jan 2009, 14:03

Mine is an 82 5.7 lte diesel Cadillac bustle trunk, it lives in the UK. I have rebuilt the top end with the better head gaskets and special head bolts, a modified water cooling system for the cyl heads to maintain a balanced water temp (which was probably the reason for the head gasket failure in the first place). I make all my own bio diesel and the old motor runs just great.

31st Mar 2009, 11:41

I have a 1980 Olds Cutlass diesel that is the best thing that I have owned in my 68 years of age.

I still run it every day in the summer, but do put up EDITH in the winter to keep salt in upstate NY from eating it up.

Would purchase another if I knew what I know now, just to keep for my great grandchildren to run and enjoy as I have, The secret is maintenance and warming the engine up, but oh well, I am an ole fuddy, but still praise GM for this wonderful ole girl.

2nd Jun 2009, 15:59

Can anyone tell me where I can get replacement injectors for my 5.7 engine? It has the poppet type injector.