OK so here is my issue about 3 weeks ago my 07 s40 2.4i stopped driving, it runs well but when shifting through the different gears in the auto tranny it would not move. I decided to buy a used tranny and just installed it and while I was under the hood I noticed oil in the coolant reservoir. I am wondering if these 2 instances are related, if the tranny oil is mixing with the coolant and caused the tranny to fail. Could this be a bad external tranny cooler, or a bad radiator? There is no visible coolant in the engine oil so thats what makes me think its not a blown head gasket and that it is tranny fluid instead of engine oil. If anyone has had similar issues please post, any help is welcomed!
Thanks Dalton

 

oil in the coolant is usually a sign of a head gasket fail. Not sure how you'd know if it was engine oil or transmission fluid finding its way into the coolant. I suppose its possible for some exchange of fluids if your radiator and transmission cooler both developed leaks in the exact right spot but that seems a long shot to me vs the more common head gasket fail. Did you try an HC coolant test and a compression test to get some data points for a head gasket problem? Any sign of leaking in the radiator/cooler area? Did you check the transmission fluid level and color?

 

the issue is that i dont have the old tranny and already installed a used tranny but but didnt notice any coolant when I drained the oil out of the old tranny. I will have to do some compression tests to rule out the head gasket