Cadillac Repair: Engine Seized - Is Transmission, alternator belt, cadillac sedan deville

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I have a 1984 Cadillac Sedan DeVille, 8-250 (4.1L) V-8 engine, rear wheel drive with a seized engine (attempted to turn engine using socket wrench on the crankshaft pully nut, it did not turn).  I removed the spark plugs and this did not help. I sprayed a tablespoon of Marvel Mystery Oil in each spark plug hole and let it set overnite - the engine still did not move.  In the Chilton troubleshooting chart it mentions after removing plugs and engine still does turn that the engine must be disassembled for furthur evaluation if it is known that the clutch and transmission is free.  My question is how do you know if the transmission is free?  After the car stalled out the car was towed by a wrecker truck (rear wheels were lifted up by tow truck), also the car was moved from street to driveway by putting it in Neutral and pushing it  - does this mean the transmission is "free"?
Answer -
Hi Linda, Sounds like you have a bad situation here. The fact that you had the car towed and pushed and didn't leave skid marks means that the trans is free and not bound up. One last thing to try is loosen or remove all the accessory drive belts and see if the engine will now turn over. I have heard where at a dealer that an engine was replaced only to find that an alternator had locked up and the new engine wouldn't turn over eithor until the alternator belt was removed. Maybe you could be that lucky too. Since you already have the sparkplugs out try putting up to 4oz of MM oil in each cylinder and let it sit for a couple of days and see if that makes any differance if loosening the belts doesn't help. Good luck. Bill

Thanks for responding so quickly - I loosened all the accessory belts and the engine still doesn't turn, I added 4 oz of MM oil in each cylinder and will wait several days to see if the engine will turn over.  One more question - could a broken timing chain cause the an engine not to turn?jammmedcause

Answer
Hi Linda, Lets hope for the best after a couple of days. Removing the oil pan isn't too hard a chore on this engine and maybe removeing it might shed some light on the problem. Yes it is possable to have a timming chain or belt break and cause the engine to lock up but usually when that happens you can still turn the crankshaft alittle bit back and forth although when a piston hits a valve is when the engine will stop rotating. These are called interferance engines. I would say that 75% of the engines out there can break a chain or belt and not cause any problems. Your engine should still turn over even with a broken chain because it is a non-interferance engine. Bill