Mechanics

OIL IN COOLANT RESERVOIR

2004 Cadillac CTS

Engine Cooling problem
2004 Cadillac CTS 6 cyl Two Wheel Drive Automatic 90000 miles

2004 CTS 3.6L Found oil in coolant reservoir when I thought I had a coolant leak. Leak looks like it came out of overflow tube. No water on dip stick or oil cap. Car did not over heat. Engine sound fine. Oil cooler? How do I replace?
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Deadbug
May 10, 2010.




Sounds like the oil cooler is leaking. It is a bit of an undertaking, the cooler is located under the intake manifold, between the cylinder heads. You have to remove the intake manifold to access it.I strongly suggest getting the updated GM kit that should include all parts necessary to change it, the GM is a bit pricey, but is stronger than original.I also suggest taking care of this ASAP, the oil wiull destroy every rubber coolant hose. Have the cooling system pressure flushed to get all of the oil out

Tiny
Jack42
May 11, 2010.
I was just told by the dealer the 3.6L does not have an oil cooler. I have found a lot of problems with the 3.2L online in the location you described. What is your next best guess? Thanks

Tiny
Deadbug
May 11, 2010.
If there is no cooler, it is coming from either the head gasket, intake manifold gasket or possibly a front cover. How much oil are we talking about? Does the coolant bottle have actual oil in it or was it just what ran out of the overflow tube? Has the cooling system ever been serviced?

Tiny
Jack42
May 11, 2010.
It sucked up enough oil to overflow the reservoir. When I start the car the level goes up. Very muddy in color. The thing that confuses me is the oil level appears fine on the dip stick. Unless it just leaked out half a qt or less. Could it be transmission fluid? I installed a new water pump about 6mths ago. No other service has been done.

Tiny
Deadbug
May 12, 2010.
Could very well be trans fluid. Check the level of the trans. Sometimes the internal coolers leak and will do that.

Tiny
Jack42
May 12, 2010.
It is tranny fluid. After warming the car to operating temp. It will not move in D or R. I have read that the tranny cooler lines go through the radiator on this model. My guess is to replace the radiator? Flush cooling system and tranny fluid?

Tiny
Deadbug
May 15, 2010.
Yes, the cooler is mounted inside the radiator, You could find a radiator shop to just repalce the trans cooler if you want to go that route.A radiator shop will also have the equipment to flush the cooling system to get rid of the oil.
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Tiny
Jack42
May 15, 2010.

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