Olds engine in Chevy Caprice - should I be disappointed?

Then something was seriously wrong with the diesel. Not surprising since GM dropped the ball on training. Most dealer techs back then didn't understand diesels. They didn't understand how to set injection timing, diagnose diesel EGR, or even understand that the 350 diesel used TTY headbolts. So they did a lousy job repairing them, and they ran poorly, they didn't last, and they developed a bad reputation. GM also didn't help the problem by not including a water separator in the fuel system, and falsely advertising it as a maintenance free option to gas engines.

Are you saying 30 miles per Imperial Gallon? If not I can not see a 4500 lb car with a carbureted 350 or 351 (GM or Ford) with the aerodynamics of a brick getting 30 MPG at anything above 35 MPH cruising speed. And even then... If that were the case, why weren't they marketed better? Ford Escorts didn't do better than that, and Ford didn't make near the profit on them as they did the 'Squire and the Colony Park. The Escort would have been superfluous if a full size wagon could do that. That means a Vic or a Marquis could have done over 35 stock. I can't see it.

My 1980 Olds diesel easily did 30 mpg highway, while my friend's Grand Marquis with a 302 only managed 19-20. Now it would run circles around my Olds, but my around town mileage was better than his highway mpg.

My diesel suburban gets 27 Mpg highway, nearly double the 16 MPG it did as a gas 350.

 

That's an understatement. My brother bought a Chevy pickup with the Olds diesel in it. It developed problems in the first year and spent more time at the dealership than in his driveway. I think the factory rep worked on it a couple of times too. They never did fix it, took it back, and gave him what he paid for it towards a new truck.

I refused to work on them in my shop....not because they were problematic but because they stink and make too much noise and the fumes made me sick to my stomach. We did have fleet accounts with diesel trucks, but I always made my Ace mechanic work on them in Bay 7 (the parking lot)

 

This has been before, I personally have owned a 351W Colony Park and there is no way even if your driving down hill both ways in neutral are you going to get that kind of millage even after upgrades These bricks on wheels would still be in the show rooms if that were the case.

 

Mike was the butt of the old prank where your buddies add extra gas to your tank......but they never let him in on it.

 

I worked on the 350s at an olds dealership. I learned from a former diesel/heavy equipment tech that had retired, got bored, and went to work at the Olds dealer. Our shop was kind of a niche shop in the area. Even though we were an Olds dealer, we had alot of Ford diesels, non-Olds GM diesels, even Mercedes, Peugot, and BMW diesels showed up. He taught me that the factory head bolts, rod bolts, and main bearing bolts all sucked. GM head gaskets sucked, (for the 350 diesel, not other engines) and by extension, Fel-Pro head gaskets (aftermarket copies of the OEMs) sucked. The way to fix them right was with the ARP hardware and Victor Reinz Gaskets I mentioned. I built several of them on my own after the I did 2 or 3 with him. They never blew up, they all ran well and while a gas 350 Chevy, Buick, Olds or even Pontiac would eat it up, it would run with an Olds 307, Chevy 305, or Buick 300. It would also get excellent MPGs. And of the timing were set right and the EGR valve was..um.. "discouraged" from opening up so much, they didn't even smoke much. Whenever I see one of those old diesels belching smoke I know it needs a tune up.

 

Testing my new signature.

 

Argo: The diesel I mentioned was the 3rd one in that car, not a rebuilt, either, but a new replacement after a 'gas jockey' made that very mistake. It was as the factory built it, and only had about 50,000 miles on it. My Buick 350, with the Turbo 400 transmission, did indeed to 30 miles to the Imperial gallon. It would go from Toronto, Ontario to Sault Ste. Marie, Mich. on well under a tank of gas, and nobody was adding gas, as I just simply did not stop.

My brother had an 86 Colony Park, 351, and Trailer Tow III package. With an Edelbrock 1401 square bore carb on the Performer intake, with a GOOD dual exhaust, he could do a solid 1,100 kms on a single tank, and that tank is 70 litres. That is a solid 40 miles to the Imperial gallon, day in, day out, and it was still doing that when the engine and transmission had 750,000 kms on them. 2.73:1 rear axle, .6:1 overdrive, and the right tires, with the engine set up and tuned properly, and there was no hanky-panky. Toronto to Parry Sound, Ontario, and back TWICE on a tank is 1,100 kms. Not too shabby at all.

 

unfortunately Mike's, Brother's friend driving ahead was struggling to get 10MPG both times on that same trip in the same car but with the even better trailer tow IIIIIIIIIIIII package that included from the factory extra heavy duty muffler bearings.

He was over heard commenting...
"I just can't believe the MPG your getting, I have to fill up at every station?"

All Mike's Brother did was smile with a evil smerk

 

I was thinking that. Maybe the 350 diesels kept blowing up due to that (they weren't meant to pull 2 cars behind the one they were installed in). Or I was thinking dangerously close drafting to semi trucks. I have no doubt that a Colony Park could get 40 MPG Imperial if cruising 6 inches from the rear of a Tractor Trailer at 60 MPH. I watched that episode of Mythbusters.

As for my 350 diesel powered Olds 98 that I had in high school and college, it was number 2 for the car. My grandfather bought the car in 1980 and the original engine let go at 12,000 miles or so. The engine was replaced with a Goodwrench engine and it went another 240,000 or so miles and was still running strong until a tractor trailer rear ended the car while I was sitting at a red light. The crappy Turbo 200C trans went up 3 or 4 times in that car. In fact the trans was dead when he gave it to me. He said "if you can fix it you can have it". So I did the only thing you can do to properly fix a TH-200C. I replaced it with a TH-350C. The Goodwrench engines (and the DX block 2nd gen engines) were way better than the originals. That engine was smooth and efficient. It wasn't particularly fast, but I could run with 2bbl 305 Chevys and beat Buicks and Cadillacs with 4.1L 4bbl V6 engines. I even beat a 4.1L Cadillac V8 Eldorado. But I think it was sick, because the caddy blew up the next week. (They were way worse than the 350 diesel. When I worked at a Caddy dealer, the joke was that the engines were made for Cadillac by Hamilton Beech, because they were so good at making milkshakes). The reason I attribute to the 350 Diesel I had lasting so long was that my grandfather had a truck shop install a water separator, and I changed the oil every 3,000 miles with diesel rated oil (alot of 350 diesels got the same oil as a gas engine... bad news there).

 

Just found this thread from three years ago. Does anyone know what happened to ProudPiDonk and which wagon s/he chose?

 

This is my first time seeing this thread...man, some hefty claims were getting thrown around! A 351W Colony Park getting 30 MPG? Half that, IF that! The only way to get anything over 18-20 on the highway was to shift into Mexican Overdrive and shut off the ignition. Then you can get as much high MPG as the length of the hill....

 

And I can see the value of a water separator for the Olds 350 diesel, but no matter how good diesel mechanics can be, those engines just could not stand the really high compression. GM was being cheap, and it took a big chunk out of their @$$ as well as corporate profits. I'd say 'Serves them right,' but we were the ones truly inconvenienced.

 

Then there were the 40mpg claims with the 400 Ford..... Can't remember exactly but I'm sure he could have gotten a 460 Ford to drive from coast to coast on one tank of gas!

 

That yo-yo must've grafted a Caddy V8-6-4 control system on it.

 

Nope. Just need long tube headers, a true dual exhaust with an x-pipe, and the proper jets in a Carter/Edelbrock carburetor and you can get like 500 miles to the gallon out of anything.