oil in radiator - Vortec 5.3 LM7
I have Chevy Express 2007 AWD with Vortec 5.3 LM7 engine. I have found oil in coolant - milky stuff below radiator cap. I discovered that mix oil-coolant comes from little tubing which goes from the engine head to top of the radiator. I dont see any coolant in engine oil. I didnt experience overheating, engine codes or excesive or low oil pressure. Nothing. Van was driving OK - I guess I just have found it before it could make a mess.
My question is what could be the issue:
1/ transmisiion cooler - maybe it is transmission oil in coolant but why I see oil/coolant mixure enetering from the tubing which goes from cylinder head?
2/ blown head gasket - how to verify that? I did combustion leak test (suck air from top of radiator and checking if testing fluid goes from blue to yellow) with negative result. Seems the head gasket is not blown in cylinder area. Could be head gasket blown in oil passage only letting oil to enter coolant? How can I verify that without removing the engine head?
Thanks for any opinions/advice.
I hope you don't mind if I post your photo from chevroletforum. It helps for diagnosis.
the Strawberry Milkshake of Death
but the head gasket of vortec 5.3 LM7 looks different that on e on your picture though. Can be seen here https://www.rockauto.com/en/catalog/...ad+gasket,5412 or on the picture below. There is place where engine oil can leak into the coolant. Still very unlikely though. I'll check that tranny cooler and hope that is the case.