Edited and compiled by Ed Barnett 69-911T cum 73RSR

This email series from a Porsche 928 racer friend:

I have oil pressure issues with my car and may not make the

Thunderhill event. Have the cam covers off again tonight

trying to find a mysterious lowering of OP at high rpms.

Been all through the extra plumbing and the pressure relief

valves, etc with no luck so far. Nobody has any further

ideas. I may end up doing a dry sump system sooner than

planned, if I end up having to drop the pan...on a 928 that

is pretty major.

So my last chance for this weekend is tomorrow, when we are going to fire it up with the cam covers off to see if we see some oil squirting out somewhere bad.

The OP was fine until we dug into the cams.. so it is not big end bearings (also, good oil pressure at idle, and when you first rev the motor, then it drops back right quick to 3 bars from the normal 5 bars. If you idle down, the OP climbs to normal 3.5/4 bars and holds. Then you run her up and it goes up like normal to 5 bars, then Pssssss....right back down to 3 bars, even if you hold the revs or increase from like 4 to 5 grand, still on 3 bars..not good for a race car..

Hopefully something will show, but possibilities are

getting fewer as I keep eliminating things it MIGHT be....

Did you get it figured out???

E.

No. I've almost given up trying to find it on my own. I

have "stumped the Experts" Lots of very knowledgeable 928

pros have been consulted with no new ideas coming forth. I

have done everything we can think of with no change. Been

working on the thing for amost 3 weeks total(counting the

time for the cam/spring swap) and I am getting plenty

frustrated.

So, Marc T. came up with one final thing to try(I will take the guts out of the oil thermostat, which in essense will return the oil system to 1979my operating mode. He thinks it might be possible that one of the SS oil lines was/is collapsed inside the SS covering and as it heats up it collapses..I have my doubts that this next test will do any good..but..

Next plan is to take it either to Devek or I have two

fairly good places here, one in Portland, one in Seattle.

Drop the pan and check all the internals, swap in a new oil

pump(they are not known to break often..)and last resort,

dismantle the whole frigging motor..

I have another big PCA/SCCA race in two weeks, the Portland Rose Cup. Hope to find the problem before that one as I've entered double--PCA National and SCCA in two classes. I will be a busy driver on that weekend, but I love the track time..

Did you get it figured out???

Yeah, I found the problem on the very last try..I was

disgusted at spending all my time in the oil without any

results, and at a loss for any new ideas. I was all set to take the car to Deveks, ready to stick it back together and load it for the trip down. Marc T had no idea what they were going to do, except pull the motor to take the pan off and look at everything, but he suggested that before I bring it, I fish around through the oil drain plug hole.

I'd already thought of this, but didn't think any way could I get any real results sticking a bent wire or something in there. I was considering getting an 'scope and looking around in there, even.

Anyway, "grasping at straws" I bent a peice of welding rod and sure enough, I felt something "not metal" in there.

Cut to the chase, it was a quarter of a shop towel that we'd used to plug the oil galleries from the cam covers back down to the pan, to prevent dropped nuts and bolts falling into the sump! Must have missed one of 8 of them and it was partially blocking the oil pick-up, restricting the flow at higher rpm!

Dumb, Huh?

So, Thursday I am off to PIR for a test day, Fri, Sat and Sunday is a PCA/SCCA joint race weekend called the Rose Cup races. I will be running both clubs events, so making up for missing last race at Thunderhill.

And best of all, my car has new cams that seem to be on the "up-curve" of the hp band when I hit my rev limiter...I have a new chip coming with a 7500rpm limit, should be here in time..