On my 94 z28, stock with about 70,000 miles has developed an oil leak between the oil filter and the filter boss on the engine. My underside of the car has had an oil bath from the engine back. I changed the filter, but the leak persists, also I have oil on the driver side tail pipe on a single cat - cat back system. My PCV valve sounds ok and rattles like a new pcv valve.

Any help appreciated, car runs very smooth right now and I am using synthetic motor oil.

Any responses appreciated,

Thanks everyone.

 

does it have a oil cooler?

you sure its not the rear of the intake leaking oil?

 

It does have an oil cooler, but I can see the oil leaking out around the filter, or the part of the engine that the filter screws on to. All above this area and in front of this area is clean and oil free, as best I can tell.

 

You sure the old oil filter gasket came off with the old filter and isn't still stuck to the block? Maybe the old gasket was leaking and when you removed the filter it didn't come off and you screwed the new filter and gasket onto the old one.. Just a suggestion.

 

I would def look at the oil cooler for the leak. I had a persistant oil leak, i eliminated multiple things I thought were the problems...it ended up being the oil cooler. Once I pulled that off, the leak was gone...just food for thought. Also fron what I understand the rear of the intake is notorious for leaks.

 

check and make sure the old gasket came off with the old oil filter.

 

the contact area where the filter meets the engine is bright rust free metal.

 

You can try tightening the big nut in the center of the oil cooler (when filter is removed) to see if that helps, taking the oil filter on and off can make it loose. If that doesnt help, lower the cooler and replace the O-ring there. Had that same problem with my Z that I recently sold and to correct the leak it took a new O-ring.

 

Thanks for the replies, everyone.

I finally got the car fixed today and it took a new oil cooler assembly to fix the problem. The part cost $412 and some change, so it was not cheap to say the least. However, this car has been mine since new and has only 71,000 miles on it. I can get behind the wheel and I am 25 again for a little while, with all the stress of life, it is hard to put a price on that feeling.

 

Don't know nuthin' bout no oil cooler, but I'd make sure that when you change your oil and filter that there is someway to make sure the cooler is also free of debris. No oil pressure no bearings. JMHO

 

Wow, you could have eliminated the oil cooler and saved yourself $400+. When I did that I picked up abut 10psi of oil pressure across the board, and my oil cooler had alot of trapped gunk in it.

 

The inside of my engine is as clean now as when I bought the car new.
Oil has been changed every 3,500 miles and the old cooler is as clean on the inside as the new cooler.
The cooler is nice when I am autocrossing.
Thanks for the replies.