Hypothetically speaking, let's say this is a manual transmission car so tranny fluid does not run through the radiator. Furthermore, let's say this car has no oil cooler; the type that circulates coolant through an adapter sandwiched between the block and oil filter (similar to factory coolers found on our cars). Also, let's say the heads and head gaskets were recently removed and checked for cracks, leaks, etc. and found okay.

My machinist says that the only other possibility, although very remote on a small block Chevy, is an internal crack in the block. Is there any other way oil finds its way into the coolant? And knowing the heads and head gaskets are good, is there a conclusive "test" to determine if a cracked block is causing this? Maybe some sort of dye in the oil????

My machinist also says there is no way to test the block for this with the engine disassembled. Is this true?

 

A cracked intake manifold would mix oil with your coolant, but you didn't state you were losing coolant just getting oil in it.

Other than bad gaskets or seals, its likely the block is damaged.

Don't know of a sure fire test to check for a cracked block, but I would think a compression test would be a good place to start.

 

hmmm, I would try to pressure check your cooling system.
You might just have a very dirty system?
Clean you heck out of your over flow container. This is often overlooked.

Ron

 

I think mine is doing the same thing. My reservor has a lot of nasty black soot in it. I never noticed it do it until after I replaced the intake manifold gasket. I think I made a mistake when I coated the new gasket with gaskacinch. I'm going to clean it out and see if it turns brown again. One other thing when I smell the coolant it smells a little like exhaust gas. Any comments guys?