There's a fair amount of info re: replacing oil cooler lines on the '87/'88/etc., but my oil cooler is separate from the radiator and I couldn't find anything related to replacing the O-rings on the cooler @ the lines.

A couple months back I fought with my C&R aftermarket radiator & fan shroud to get them to allow the hood to close properly. I suspect that my oil cooler line connections may have suffered from all the movement in the process while the cooler was temporarily unbolted from the frame. It appears to now be leaking here.

As best I can tell, there are two lines going into the driver's side end of the oil cooler with a metal plate over the them where they go into the cooler. This metal plate is seemingly attached via a center-mounted bolt only.

First I correct about the design?

I'm suspecting the O-ring needs replacing, but I'm not sure. Is it as simple as:
removing the single bolt to the metal plate > pulling back the metal plate and exposing the hose-to-cooler union > pulling out on the lines to disengage them from the cooler > replacing the O-rings > pushing the hoses back into the tank union > remounting the plate with the bolt?
Or, (as I suspect) more to the project?

Any help would be appreciated. Please note that I'm not as mechanically savvy as many of you; so I'm likely to require a more detailed description.....sorry.

BTW, I looked at the PET, but it wasn't altogether clear either as the oil cooler is expressed on one page and the lubrication system with lines on another.

I know pics help you guys to help me, so I've included one (blurry), with a rough sketch of the details missing in the photo. The lines have been wiped clean, along with the bottom portion of the "metal plate". There may be more detail to the upper portion of the plate that I cannot see due to cosmoline/dirt.

Thanks again for any help.
Attached Images

Nicholas Bryant

Your description and expectation of what you have to do is exactly right. Those o-rings (900 331 022 40) are damned expensive (>$5 each...) for what they are, aren't they? The job is a simple one, but messy.

Actually, if you could do me a favor- while you have the lines disconnected, could you measure the length (in mm) of the threaded portion of the socket cap screw that holds the lines to the cooler, that would be great. PET doesn't list a length and mine is disassembled right now. I have a big bucket of bolts and don't know what size to use there.

This is what the cooler lines look like naked:


Rob Edwards
1990 928GT #278, Black/Black, C03 048 418 474 498 538 570 850 691 935 980 112K miles

I have had mine off a couple times with no problems. It is just as you assumed with simple O rings.
Rob... the cap screw has a washer attached and is 26 mm to the head with 21mm of thread, overall about 34mm including the allen head
Here is a picture of my connection....Rob this is the fastener

90 S4 Auto 82,000 miles


I had a leaking oil cooler. Something at some point hit the cooler, and not it is dripping a bit. It is getting worse gradually. I was told that using 2-componentr glue with some alcohol to make it flow like honey would seal the leak. tried 2 times, with no success at all. So I decided to stop a crappy repair and buy a new one. The unit is a OEM Langerer & Reich and carried the Porsche 928 part number pressed in the aluminum.

I bought the cooler at ... not listed but they do supply at 271 euro's (aug 2010) It took some black paint spray since it was aluminum colored but a 100% perfect fit. No issues anymore.