Fabio421

I pulled both the oil pressure reliefe valve and my oil bypass valve plugs. The spring is missing from the bypass valve and I cannot get the plungers out of either one. In fact, I'm not sure I have plungers in there either. Can anyone tell my how this system works so I can figure out if my missing bypass valve spring has anything to do with my pushed out front crank seal? Please help me determine whether or not the pistons are stuck in the holes. From looking at these pics, it appears that the hole on the right (bypass) has no piston. It looks like the hole on the left does have one but I think it is stuck.

Some history of my problem. Its a 1982 car that I bought and then promptly blew out the crank seal. It blew out during my first test drive once pulling it off of the transport. The front crank seal was pushed out on the passenger side and I lost about 5 quarts of oil in < two miles. I am almost finished putting the car back together now and someone mentioned in Tass' thread that I should check the oil relief because they had a similar seal failure when their relief piston got stuck during a 10 year span of being garaged. What purpose would it serve to remove this item? Could it being missing cause my issue?


Please help me get this car ready for our Fri. night central FL get together.

Thanks in advance

Mrmerlin

does your car have a oil cooler?

Ketchmi

It appears that the larger hole has no plunger and it should be approx. 2.6" from the surface to the deepest part. There is a "V" shaped oil galley behind both plungers and should measure the same depth on both. I can't tell from the pics if there is a plunger in the smaller one but the galley in the back of it should look just like the larger one.

Hope this helps...

Fabio421

Last night I spoke with John K. and he made me feel alot better about things. As it turns out, the bypass valve is used only when you have an oil cooler. I do not have an oil cooler. I am using one of the oil cooler ports to oil the turbo. If the valve was installed it would restrict oil to the turbo at low engine temps. Not a good thing. So I'm OK in regards to the missing bypass valve. Now I just have to figure out how to get the relief valve poppet out of its bore. Any idea?

Thanks guys. it seems that the plunger may be in the smaller hole. The back of that hole is blind and not similar to the larger one.

Tampa 928s

Welcome to my world Now the lift is acting up, I think this Euro has the soul of Hitler floating in it!

Ketchmi

"Last night I spoke with John Kuhn"

Well there is your problem right there! lol (joke!)

The bypass for the oil cooler is above the oil pressure sending unit, the large aluminum nut pointing toward the ground with the two ports directly above it located in the girdle, not the block. There is a thermostat located in there which moves a plunger redirecting oil flow through the cooler when it reaches a specific temperature. I don't think you are done yet...

Tom. M

Haha..funny..I've been there too..just replaced the piston in the first smaller hole (no need but figured might as well). There should be a spring in there and I believe that is the high pressure bypass that re-diverts oil to the sump if pressure exceeds 8bar. I would get a spring in that one.

My block is a 91 so I don't have the second port (According to Jim B, Porsche didn't see the need for it since the oil cooler was external and a leak would be obvious)???..

And yes if you are adding a cooler to the motor, get the oil regulator insert (928-1-0-172-02) and two springs (928-107-171-01 and 928-107-173-00) in above the oil presser sender. Without it, when you fire up the car, it will be forcing oil through the cooler and cold 20w 50 doesn't like to be forced through there that quickly..resulting in some upper end noise till the oil warms up. (don't ask how I know) ..

Fabio421

The hole on the left is the pressure relief and the one on the right (while looking at my pics above) is for the bypass. This was verified via the WSM. Are you saying that the WSM is wrong? Remember, this is an 82. I believe they were reversed in the later cars starting in 1983. As for the technicality of whether the particular segment of engine is considered block or girdle is irrelevant IMHO. If you say it's called the girdle, I believe you, you know more about it than I.

Tass 928

I was planning on opening mine up tonight...

Fabio421

Ok, I got it out. It wouldn't come out with the magnet so I used one of the long bolts for the alternator to get a grip on the little bugger. I polished up with 1500 grit paper and put it back in with a little oil. I should be ready to fire this thing up within the next couple of hours. I'm going to do a compression test first to see if I have a broken ring or something. I really want to find a reason why my seal was pushed out before I fire this sucker up and blow it out again. It may have been the oil relief but I'm not convinced.

I'll keep you guys posted. Maybe I'll make a Olsen'esque first start video to share.

Fabio421

Alright, update time. The car is back together and running. I even took it for a drive around the neighborhood. It ran fine and best of all.............................NO LEAKS!!!!! Now I just need to put the belly pan back on and give it a good washing. Tomorrow will be spent cutting through the govt. red tape so that I can get it registered. I sure hope the inspection by the sherrif doesn't include a look at the underside of the car. I would hate for him to see a 3" exhaust, a wastegate and no cat staring back at him. I don't need those types of problems right now.