nocomment

So recently my 86 Porsche 944 NA had an engine totaled by #2 rod bearing failure. I recently finished rebuilding a junkyard 86 block and installing it in my car. The reason I am posting this in the turbo thread section is because I did two modifications to the stock oil system; I installed a 86 turbo oil filter housing and external oil cooler as well as welded in a Lindsay racing oil pan baffle kit. Since this is a question about the turbo oil filter/oil filter housing specifically I felt this was the right place.

First a story on how I deduced the leak is coming from the oil filter:
This oil filter housing is proving to be a real pain my butt. I recently made a thread about a leak from the oil thermostat cap which i thought was the only leak in that area. Thanks to the thread(you guys are awesome) I was able to replace the crush washer and reseal it. That no longer leaks. Went to prime the oil system and no leaks. Then i proceeded to start the car for the first time and it fired right up and ran perfectly until i checked underneath the car. It now leaked from either the AN adapter fitting or AN hose end. I turned the car off and ordered replacements of both. After I replaced the the AN hardware I started the car and there were zero leaks, so I let the car run for its 30 minute break in while bleeding the coolant, etc. I change the oil and filter and set the car down to be driven for the first time in 6 months. I start it, but it in gear, move it an inch and make sure the brake works, and then get back out to check the engine bay one more time. Lo and behold, oil dripping from the same area. I think at first the new AN hardware is bad again, so I jack the car up and start it again, and put a paper towel above the AN fitting and below the oil filter to see if its coming from higher up. The steady drip stops and the paper towel takes oil, confirming its coming from the oil filter.

I've already tried putting my oil filter wrench on it and over-tightening it, which surprisingly made it leak a lot more. There are no nicks in the sealing surface of the oil filter housing and the gasket on the filter showed now tell-tale signs of flaws.

I have a hunch it may be high oil pressure related maybe from the OPRV, but the gauge read 4 bar at idle. I'm not sure if the sender reads oil pressure straight from the pump before it gets to the OPRV or after, or if that would even matter. Oil filter is Wix brand, Oil used is Castrol GTX 20w-50. Wix is a decent quality filter and I had no problem with them on my old engine. I think the 3 possible causes are high oil pressure/bad OPRV, bad oil filter, warped oil filter housing. I'd really appreciate your input on what it could be or anything i've overlooked. I think i'll try and find a different brand oil filter in the meantime and let you guys know if that fixes it.

wildcat077

I don't think it's a pressure issue ... the cold pressure on startup with my race engine reads 80-90 psi with an Autometer mechanical gauge, that's with a brand new OPRV.
I would guess it's possibly a warped oil filter console.You can always try a Mahle filter and check for leaks again , it might eliminate that issue !

For what it's worth , i have an 86 turbo oil filter console and Lindsey cooler with braided hoses as well on my engine.

nocomment

Thank you for your response, I did go out yesterday and got a STP oil filter from autozone(only one I could find in stock anywhere). When I got back I ran my finger along the sealing surface on the housing, checking for anything I could have missed. I then noticed there were a few dings on the edge near the cooler fitting. They pushed the very outside edge of the sealing surface very slightly above the rest of the surface. I then compare the Wix and STP filter and notice the Wix has a much thinner gasket, and i realize that it's entirely possible that the one or two tiny dings could be pushing against the metal on the filter causing it to go on crooked which would explain the leak getting worse the tighter the filter was. I use a file to flatten the dings and install the STP filter. Started it up and drove it 100 miles leak free so far. I'm surprised the dings were large enough to cause a leak as big as it was(a steady stream at times) but they appeared to be the cause of the leak. Thank you for your reply again!

wildcat077

This is what forums are all about , but in my opinion you should't cheap out on oil filters ... you saw for yourself the difference in quality !
Just go on Amazon and order a half dozen Mahle filters , get the turbo ones , they're a little taller and have more filtering ability than the regular OEM N/A units.

nocomment

I had no idea the turbo had a different filter. May as well stock up on some of those. Thanks for the advice.

mj951

It's actually the oil filter spec'd for the 928, it's a little taller but many, including myself, use it on a 951.
Mahle OC 75

JustinL

I have a similar leak in my new build. I thought the same about the filter leaking, but there is actually a way for oil to sneak down from the camshaft seal to the filter. I can't see exactly how it's doing it, but digging into the camshaft pulley area definitely revealed some fresh oil. Have a look in there before you go too wild on the filter housing etc.

nocomment

oh the little nicks in the filter housing were for sure the cause of the leak(i filed them down and it no longer leaks at all). I've also heard of the camshaft seal leaking down there but this leak was pretty bad(almost a steady stream) and clearly coming from that area, not like a slower leak that would be harder to track. I'm halfway through the 500 mile break in period on my new engine and its been leak free so far.