I replaced my engine oil cooler due to having oil in my coolant. I can not get it to seal and not leak. I have replaced the o ring with no luck. The other thing I could think of would be I have the coolant lines backwards and it is forcing the oil past the O ring. Any help would be appreciated.

 

 

Did you make sure to install the top o ring dry?

 

What brand replacement cooler is that? Have not heard good things about aftermarket parts, Dorman seems to get the most mention for being problematic however that could be due that brand's general popularity for OEM-like parts.

Is the fastener holding the cooler assembly to the block tight?

If you replaced the coolant lines as they were installed on the original cooler that shouldn't be an issue.

Hope you get this solved--that would give me nightmares.