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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / June 2007Replacing Olds 5.7l diesel head gasket
What procedure should I follow? Do I need to remove the bolts in a specific order? It is not worth contracting this work out to anybody. This could be an exercise in shear folly if more than the gasket needs to be replaced. > What procedure should I follow? Do I need to remove the bolts in a > specific order? It is not worth contracting this work out to > anybody. This could be an exercise in shear folly if more than the > gasket needs to be replaced. >From memory, have the head checked for straightness. While it is off, have a good valve job done on it and check the guides.. You MUST put in new head bolts. Disassembly order is not important. Assembly is. Follow the procedure in your repair manual. >What procedure should I follow? Do I need to remove the bolts in a >specific order? It is not worth contracting this work out to >anybody. Anybody who would be knowledgeable enough to do a profession job would, hopefully, also be honest enough to tell you its a really bad idea. > This could be an exercise in shear folly It is sheer folly. The diesel version of the Olds 350 engine was an unmitigated disaster. The Olds 350 was designed for 9-10/1 gasoline compression ratios and then a diesel version was hasily conceived with much higher compression and attendant stress. About all they did was increase the head bolts from 7/16' to 1/2' It wasn't enough and the engines blew head gaskets all the time. among other problems Many who had such an engine in their PUs converted them back to gas. I can remember when this was a commonplace operation. A diesel engine needs to be built for diesel from the ground up. Don www.donsautomotive.com >if more than the gasket needs to be replaced. > It is sheer folly. The diesel version of the Olds 350 engine was an > unmitigated disaster. The Olds 350 was designed for 9-10/1 gasoline > compression ratios and then a diesel version was hasily conceived with > much higher compression and attendant stress. About all they did was > increase the head bolts from 7/16' to 1/2' It wasn't enough and the > engines blew head gaskets all the time. You're partly right. It's loosely based on the gas 350, but that's not necessarily a bad thing if it's done right. GM's big mistake was not adding more head bolts, which led to the head gasket problems. The problem can be helped by never re-using head bolts, but the best solution is to use head bolts (or studs) that are strong enough. There are lots of these engines still running perfectly, and getting 30+ MPG in 4000+ lb. cars. > among other problems Many who had such an engine in their PUs converted > them back to gas. I can remember when this was a commonplace operation. Commonly done "back in the day" by those who knew nothing about diesels, but a real pity, and a complicated solution to a simple problem. There's lots of good info on the web about these engines and how to fix the head gasket problem. Once that's done, it's a solid, economical engine. -Dan '81 Cadillac Sedan DeVille, 5.7L diesel >> It is sheer folly. The diesel version of the Olds 350 engine was an >> unmitigated disaster. The Olds 350 was designed for 9-10/1 gasoline [quoted text clipped - 6 lines] > necessarily a bad thing if it's done right. GM's big mistake was not > adding more head bolts, which led to the head gasket problems. Well, there was another big factor, too. GM put these engines in cars that were built for gasoline engines and didn't have the added fuel filtration, water/fuel separation, and general water-vapor resistance that diesel fuel systems need. Combine that with a Roosa fuel injection pump that wasn't exactly the most rugged in the world, and you got a lot of cases of very uneven cylinder fuelling. In other words, a few cylinders would be trying to produce a lot more power than others, so the pressures in those cylinders would shoot sky-high and blow gaskets (or pound bearings, or break pistons). Attentive owners who could have recognized the sounds of uneven fuelling would have helped too, but diesels were a very new thing to most consumers back then and many owners simply didn't know the engine wasn't running right until the damage was done. >>What procedure should I follow? Do I need to remove the bolts in a >>specific order? It is not worth contracting this work out to [quoted text clipped - 3 lines] >would, hopefully, also be honest enough to tell you its a really bad >idea. I know several in the Cadillac club that still have them or had them running well over 200k. They were much better in the later years than the early years. Still slow and stinky but they didn't croad as easily. To the OP: As others have said make sure you use new bolts. Tighten them in the proper sequence with a torque wrench. I would even go so far as to recheck them after you had a few miles on it as the headgaskets were a known trouble spot on those engines. Do it right and you should be fine. Steve B. . > A diesel engine needs to be built for diesel from the ground up. Well, there are a few good conversions out there. The first Ford Powerstroke (the 7.2 liter version) was originally an International Harvester gasoline industrial engine. But it was extensively modified for diesel use, first as the non-turbo Ford diesel in the 80s, then as a turbo-diesel, and finally as the intercooled/turbo Powerstroke and International T444E. Interestingly, the smaller Powerjokes that are causing so much trouble these days WERE designed diesels from the start and aren't half as reliable as the previous one. Go figure. > What procedure should I follow? Do I need to remove the bolts in a > specific order? It is not worth contracting this work out to > anybody. This could be an exercise in shear folly if more than the > gasket needs to be replaced. If you don't have one I suggest that you get a repair manual for that engine before starting disassembly. Be sure to check that the mating surfaces are flat. >> What procedure should I follow? Do I need to remove the bolts in a >> specific order? It is not worth contracting this work out to [quoted text clipped - 4 lines] >engine before starting disassembly. Be sure to check that the mating >surfaces are flat. Fixing that engine is an exercise in sheer folly. It will not stay fixed. They never did. --scott  Signature"C'est un Nagra. C'est suisse, et tres, tres precis." > >> What procedure should I follow? Do I need to remove the bolts in a > >> specific order? It is not worth contracting this work out to [quoted text clipped - 10 lines] > -- > "C'est un Nagra. C'est suisse, et tres, tres precis." Yours is not an answer to his question. He asked how it should be done and not whether it should be done. John S. is right.Get a repair manual/book for that model vehicle before you even start working on it.(engine) The same is true for all vehicles,gas or diesel.Check your local auto parts stores or libraries for a book on that model vehicle.A book store can probally order a book for you or look around online,perhaps Amazon. cuhulin |
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