Due to impending track time and my total inability to resolve the problem, I tracked down a local P-car mechanic who said he was very familiar with 914s and cut his teeth working as a mech at Vasek Polak. I figure 'what the hell, can't fuch it up any worse than it already is'. So he's got my car, checks out the pressure relief valves, inspects the bores, blows compressed air through the oil passages. Air goes, he doesn't notice anything fall out. Check valves move freely. We both agree he should put in oil, new Mahle filter, and give it a whirl.

He has a pressure gauge hooked up on the engine to see what happens. I wasn't there, but apparently his gauge only goes up to 100#. It pegs shortly after starting the motor (2.0L) and the Mahle deforms just like all the other filters and oil pukes all over the shop floor. Oil was Castrol 20w50, car was inside a heated garage so temps were probably mid-60s.

He's stumped. He calls someone out in California (I didn't catch a name) and both of them are stumped.

Oil is getting picked up from the sump and pumped into the filter. Where is the next stop after oil leaves the filter? I've seen the diagram in haynes and find it not very helpful. Any ideas on what is wrong?

Possibly something in the oil galley after the fiter but before the lifters and the main bores. Something like a galley plug that was pushed in too far.


Pull the pressure relief valve on the left rear of the block and fire it up. It should puke oil out there really fast. If it doesn't, you have a blockage. Pull the motor, pull the galley plugs and start rodding out the galleys.

Do these move? Threaded galley plugs were installed when the motor was apart back in 2004. It was running fine until last October when the filter blew out for the first time.

They should not move if they are threaded plugs.

I agree with Clay. Something is plugged up or you would not keep exploding oil filters. It really needs to be checked out.

Good luck.

I believe in your previous thread there were quite a few of us who insisted that you should drop the motor and inspect it thoroughly...

Maybe you can narrow it down.

The oil leaves the pump and goes first to the filter, then to the pressure relief valve directly below. If the pressure relief valve stays closed, all of the oil flows to the cooler and thence to the main oil galleries. If the pressure relief valve is open all the way, the oil goes directly to the galleries.

So, my guess is that the restriction is somewhere between the filter and the relief valve, based on the fact that either way the relief valve is, there is some path for the oil to take to relieve the pressure in the filter.

This is a small length of passageway, and you can gain reasonable access by removing the valve plunger from below, and the oil filter adapter casting from the side. At least I think the adapter is accessable without sliding the air cooling impeller housing forward.

It's possible the adapter itself has the restriction. I recall a steel check valve in it.... But I can't remember if it was on the inlet or outlet side of the casting....

Anyway, that's where I'd start to look.

is your motor full flowed?

Yes, at this point I realize the motor must come out. Now that the car is at a competent mechanic, this can happen more easily.

No it does not have a full-flow system.

Pressure relief is obstructed or the relief valve is stuck shut.. or the relief valve in the filter adaptor housing is blocked..

OR
you have oil that is too heavy..

Lots of things can cause this, the list above are generally the only ones that happen often..

Castrol 20W50, Mahle filter, ambient air temps were probably mid 60s F (heated garage)

The engine will be coming out of the car so that things can be inspected more thoroughly. Can the filter adaptor housing be removed without opening the case?

of course!

Exploding oil filters on start up is a real messy PITA. I had the same problem happen to my freshly rebuilt 2.0 l race motor. This was a full flow system with a remote oil filter setup using a 30mm oil pump and a front oil cooler. I went thru the process of checking the pressure relief valve and made sure the springs were correct It only takes a few seconds to dump a lot of oil. I started using a Fram HP 1 filter and kept the rpm's down on start up, which seemed to help the problem. I still wasn't happy with the arrangement so now the engine is out of the car for a complete inspection starting with the oil galleys. Will know later this month if the oil galleys are the culprit.

Gord B