Hi i have a 97 chevy with the vortec 5.7 with 312.556 and i was thinking of using seafoam on my engine because of carbon build up but i also heard with that many miles seafoam would damage my engine.

SOURCE: Water mixing with engine oil

5.7's had all kinds of problems with intake manifolds but it could also be a head gasket leaking. One way to check is to pull out your spark plugs and have a look at them. One of them will should be really white looking, that is the cylinder where the coolant is leaking into. A good rule of thumb (but not always true) is that if the coolant is leaking into one of the cylinders at the very front or very back of the engine, it is an intake leak. If the coolant is leaking in one of the middle cylinders, it is a head leak.
But the only way to know absolutly for sure is to pull the intake off and look for a break in the gasket, if you see that you know its the intake manifold. If you cant see any signs of leakage its probally a head problem. Another word of advice, there is an updated gasket from fellpro that lasts longer that the OEM gasket.

SOURCE: 1994 chevy s10

Jeff to anwser your question theres a multitude of engines you can put in depending on your skill level and what your trying to achive if your looking to make it into a little sport truck why not say drop a small block 350 in it there cheap to build easy to come by and the clearence issues are not to much to over come you will have to swap out the old motor mounts and you wont have any issue with it bolting right up to your 700r4 it takes some work on the over all but i found it to be most satisfying in the long run

SOURCE: I have a very loud knock in a 97 Chevy Blazer. I

drain and check the oil for matal contamination, from the sound of things you have had a bearing let loose, should that be thecase a rebuilt long block is your best bet

SOURCE: 97 chevy pu 305 vortec, had cyl 6 misfire and

thats usually a sign of a vacuum leak, recheck and make sure you don't have any loose hoses, or cut intake seals

SOURCE: I have a 94 GMC

The loud knock you here is a bering knock.(not good)By letting oil change go so long i would assume you have caused internal damage.And you say your oil pressure is 275 psi should be around 25 to 50 psi .Bering can't last long without oil.

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