Ian928

My Girlfriend had to stop today on the way to work because the oil pressure dropped and the light came on in her 89 951. She said the pressure got up to above 2bar when she kept the rpms up and there was no lifter noises, but she parked the car and I picked her up because the traffic was heavy and she did not want to get stuck. We will try to drive it home later when the road is clear (only a couple of miles).

I have searched the archives and have come to three possible faults, in prioritised sequence:

1 Loose crank bolt
2 Stuck OPRV
3 Broken pickup tube

We do not have the correct tool to lock the crank, is there another way (rope down the spark plug hole?)

Should we order new seals/o-rings before touching the OPRV or is it OK to remove it to inspect? And what should we look for?

I am not sure if these things are connected, but maybe: The latest few days she had screeching noises when turning the steering wheel and they seemed to come from the PS pump. There was also a lot of foaming in the reservoir. We are waiting for a rebuild kit for the pump. But the question is: Could the PS pump cause the Crank bolt to come loose?

2bridges

Hey Ian

Your list of 3 is right on:
The only other items I would check before going to number 2 is oil level and plugged up filter... oil change if unknown or overdue for service.

PS issue would seem to be coincidental and unrelated.

Mike Lindsey

Two person job. Put it in 4th or 5th gear and step hard on the brakes. Torque bolt.

V2Rocket

check your oil pressure sender for leaks etc.

i had one go bad while 400 miles from home, it said i had less than 1 bar at idle and had like 2.5 bar while highway cruising. the engine was fine and i just kept the revs up until i got home, swapped senders and all is well.

hosrom_951

I recall driving my NA, then suddenly no oil pressure at all, even at 3,000 rpms.

The OPRV was stuck, turned out that the OPRV was not aligned properly using that special tool when the oil cooler seals were replaced.

That is my experience, a broken pick up tube could also be the problem.

brad-cam

New o-rings would be a good idea, but you should be able to remove the OPRV for inspection without requiring them to be replaced. But, you may find them damaged or leaking already and want to replace them. I'm not sure there is much you can check for other than to ensure it is no bound up and the parts
move freely. So long as the oil cooler plate (the plate through which the OPRV is inserted) is not removed, you shouldn't need the alignment tool when reinstalling the OPRV.

Ian928

Tonight we got the car home, and the trip made me even more suspicious about the crank bolt, because the oil pressure gauge was jumping up and down and that could mean that the oil pump drive was slipping a bit, then grabbing a bit.

I were not able to tighten the bolt with the car in gear and the brakes on, the fan shroud was restricting how many degrees I could tighten the bolt and the slack in the drive system meant I could not get another "grip". We used the old trick with a piece of rope down the ignition plug hole and were then able to tighten the torque to spec. I would say I was not far away from turning that bolt one whole revolution!

The oil pressure was immediately perfect again! Kirsti asked me to thank you all for helping us out with this, we will be back with more questions and maybe some answers soon!

V2Rocket

takes a ginormous torque wrench to set that thing to spec..

2bridges

GREAT! that is by far the best scenario to have.

hosrom_951

Man...you had some luck, glad to heard everything is ok.

Next time, remove that starter, slide in the flywheel lock and tighten that bolt up properly

Ian928

Yes we were lucky! Kirsti is a gearhead so she knew immedaitely that this was serious and did not try to "just drive home" without checking things out first.

We were able to torque it to spec with the rope down the plug hole trick! I know this is probably not the best scenario for the bearings, especially when the bolt need such high torque, but I do not think it is really a problem.