Chevrolet Repair: 1988 Chevrolet S10 Blazer oil in radiator, chevrolet s10 blazer, engine oil cooler

Question
QUESTION: I have a 1988 s10 blazer 4.3L with oil in the radiator.  There is no water in the oil.  Would this be a cracked block? or would water get in the oil as well?  If oil cooler lines were leaking into the coolant at radiator, wouldn't water also get in the oil?  What do you think?

ANSWER: Hey Anthony,

 Not necessarily.  Engine oil pressure exceeds cooling system pressure when engine rpm is up.  A leaking intake gasket could cause this as well.
 If it is equipped with an engine oil cooler in the radiator the seals between the cooler and rad often bleed out and oil will intrude there.    If you look at the fittings that go into the rad and see coolant there it is a sure bet thats where its coming from.  The plastic wells often crack as well.

Wayne


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QUESTION: so if a static compression test shows no low compression, if it were in the intake, would I find an air leak? is there a specific test to check the oil cooler lines going into the radiator and if that is it, I would need a radiator?

Answer
A compression test won't tell you anything.  And shop air no matter where you put it isnt going to tell anything either.  Its going to be a matter of disassembly and inspection at this point.  External diagnostics when it comes to internal problems don't match hands on.

Wayne