Mechanics

Oil in Coolant GM 3.0 Liter V6

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When engine oil is present inside the cooling system (radiator) it can be bad news. It could mean that the engine has a cracked block, head or blown head gasket, but don't condemn the engine so fast. Some cars are designed with an engine oil cooler that allows radiator coolant to run through it to aid cooling the oil for longer engine life. When the oil cooler fails it allows engine oil to enter the cooling system. You might ask, "if the cooler has failed wouldn't coolant get in the oil?" the answer is no because the cooling system is under 16 to 18 P.S.I. and it takes a few minutes to arrive at this pressure as the engine warms up to operating temperature. The engine oil pressure is about 45 P.S.I. as soon as the engine is started and will push engine oil into the cooling system.

The GM V6 3.0 liter engine has a problem with their oil cooler allowing this condition. This engine design is featured in Saturn and Cadillac products. If the engine has not been overheated and has relatively low miles you could still have this condition. Testing for this condition is difficult, the cooler needs to be removed and pressurized under water to detect a leak. To remove the engine oil cooler on the GM 3.0 liter V6 you will need to remove the intake manifold. The cost for the oil cooler is a few hundred for the part and gaskets, with about 4.0 hrs labor, but it sure beats replacing the engine, also make sure to use GM sealant when reassembling. If you replace the engine without the cooler you will have the same problem.

GM V6 3.0 Liter Engine Oil Cooler Replacement
GM V6 3.0 Liter Engine Oil Cooler Replacement

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Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)