Replacing 5.7L Diesel in 81 Eldorado with 6.2 Detroit


#1

Hi folks,

I have a 5.7L diesel 81 Eldorado that recently blew a head gasket and possibly cracked cylinder head. The shop tells me that no more gaskets exist, and no more cylinder heads exist as well. Rather than crushing this beautiful car into a cube, I would like to get the engine replaced. I found a shop that quoted me 5k for the replacement. Perfectly reasonable. Now I have been told that the 6.2 Detroit Diesel should fit in my car without too much trouble. However, not sure about the height. I’m also trying to put together a checklist of what I should be looking at when having such a swap done.

Any ideas or insight would be much appreciated.


#2

Lets see…Eldo, FWD, not much room for maneuvering…Will this be a salvage yard engine? Or is the five grand just for the labor…Why not just put a 350 Chevy crate motor in it and have a decent car…Putting a diesel truck motor in it will destroy the Eldorado ambiance completely…

“Now I have been told that the 6.2 Detroit Diesel should fit in my car without too much trouble.”

I don’t know who told you that but I think they are wrong…This will be a major undertaking and a successful outcome is not guaranteed…$5000 will not make this happen…


#3

You must have had one of the only running diesel Eldos on the planet. Many were converted to gasoline power, how about that? Just not the V8-6-4 disaster. The '79 came with the Oldsmobile 350 V8, maybe that would be a fairly common engine you could find. I think the diesel was originally based on the 350 Olds engine, so that might simplify conversion.


#4

Man, I agree with Caddy. I had my fill of the diesels. The 350 should fit in just fine and be a lot cheaper and a lot more dependable. There would be some electrical issues but it was pretty much the same as the 5.7. That’s what people were doing back then when they gave up on their diesels. Some shops specialized in it and might still be some old guys that know what to do. Me thinks the fuel tank, pump, etc. needs to be replaced, and the computer etc. So not cheap but a lot more fun to drive.


#5

For a couple of years, there was a regular industry converting the 5.7 Olds based diesel engine over to 350 Chevy gas power…It was not that big a deal…These cars VIN’s identified them as diesels and as such were exempt from emissions testing…I don’t think the diesels had a computer in 1981…(The gas cars did, a crude ECM) So the converted 5.7 diesel cars enjoyed freedom from emission testing and the shops didn’t bother putting converters on them…It took the EPA and states a couple of years to figure out what was going on before they demanded the conversion shops meet the gas engine emissions standards…The process moved underground…

Owners loved them…A 300HP luxury car with no emissions testing requirement…


#6

Forget the diesel. I agree with Caddyman get a gas 350 and call it good.


#7

I believe that the engine is from Oldsmobile and the 350 gasoline heads, intake manifold and distributor will bolt up and the engine will operate fine on gasoline. I have never done the retrofit but have seen the finished product on several cars with owners who were pleased with the results.


#8

Have you tried calling American Cylinder Head (www.americancylinderheads.com) to see if they have heads or if they can rebuild yours?


#9

I can’t answer the swap questions but based on history my vote is for dropping a gas engine in.
Besides, diesel is about 40 cents a gallon higher than gas anyway; at least around here.

Back in the day when these things came out I remember 60 Minutes doing a segment on them. They procured a pair of 2 year old Buick Rivieras with very low miles (sub 15k) with one having a gas engine and the other a diesel.

They took those cars around to various GM dealers trying to sell them back and I vaguely remember the top offer on the diesel version being about 1500 dollars with many times more offered for the gas engine variant.


#10

This is the way to go…


#11

@ok4460 I bought my 81 Olds diesel for $10,000. Two years later I went to see about trading it in. I think I had 60,000 on it then. I was offered either $2000 or $2500 for it. And it was a special order broham with all the options. So I kept driving it for 15 years and 500,000 miles (with several engines). Yup, that was one steep depreciation curve. First two years it depreciated $8000 and the next 13 depreciated $1500.


#12

The devil is in the details and there are a great many detail$$$$$ in retrofitting a Chevrolet engine into that car.


#13

And the crate engine is for pre-1980 cars. If he wants to try this conversion, he should contact his state DOT and see if it is acceptable to put a pre-emissions style engine in a post-emissions car. I know that the diesel was in a different category when it was born, but would changing to gasoline power require emissions equipment?


#14

Here in Denver, we had a couple of bad winters, none of those cars would start reliably, people tried starting fluid even though warned not to…These were the big GM luxury cars a year or two old…You could buy them for $1000 or less with a blown engine…A regular industry sprang up converting them to gas engines…That debacle destroyed Americans taste for Diesel engines for 20 years…


#15

@jtsanders‌

And the crate engine is for pre-1980 cars. If he wants to try this conversion, he should contact his state DOT and see if it is acceptable to put a pre-emissions style engine in a post-emissions car. I know that the diesel was in a different category when it was born, but would changing to gasoline power require emissions equipment?

Its ok to break the law so long as you know better than the law. Just ask around here, speed limits are ok to break because people know better. I would just do what I want and swap it. Darn the Laws, if you start following laws about emissions requirements, next thing you know they will show up at your door and take you away… Quit giving up your rights to speed and pollute.

Don’t you learn anything from these forums? LOL…


#16

There is a early 80’s Oldsmobile Diesel still going near where I live. I see it every now and then, I assume its had upgrades and such, but its still the GM 350 Diesel. I wanted to talk to the owner, but I have only seen it while moving.


#17

Even if that 6.2 liter Detroit Diesel engine would fit in the engine compartment (which I actually doubt), then there is the issue of mating that engine to the transmission of the Cadillac.

Is the OP absolutely sure that the engine and the transmission would mate-up with the exact same bolt pattern?


#18

If such minutia as the crankshaft not being machined out to accept the torque converter snout can be dealt with surely that bolt pattern won’t be much of and issue, @VDC.


#19

@WheresRick‌, it is useful to know the law and then decide whether there is any chance you might get busted. If the car is subject to emissions testing, that might deter someone from putting the crate engine in. And unless you do all the work yourself, someone knows what you did. It’s just one car, and emissions are probably better than the diesel would be. But I doubt that matters much. I’d just hate to spend all that money on a crate engine and not be allowed to register it.


#20

The 81 Eldo can fit virtually any engine you want given that it held a 500 inch Caddy motor. The Olds gas motor of 307, 350, 400, or 455 will drop right onto the engine mounts and bolt to the tranny with NO mods, The Olds diesel was based on a beefed up gas block with different heads and intake. The top can be converted over to gas parts if you know what you are doing. The late Joe Mondello was such a guy and a great hot rodder. A big inch Caddy, a 472 or 500 will also bolt up but may need different motor mounts. I’d stick with the Olds but both are getting very hard to find in any condition.

Any Chevy will require an adapter plate for the transmission because the bolt patterns are different. You may have to fabricate engine mounts because a Chevy was never dropped into an '81 E body FWD automatic. With that much work, you might even consider a DMax diesel swap. It would rock!