My 86 944 looses oil pressure. At start up it runs fine, pressure about 5 bars. It appears that about 2100/2200 rpm the pressure drops to near 0 immediately. If you shut the engine off and restart, the pressure comes back up to the correct pressure. It will once again loose the pressure when your rpms hit 2100/2200 rpm. My mechanic changed the sending unit and problem still exists. Verified oil pressure by placing gage at sending unit also verified that the pressure is actually dropping to 0 as shown on the gage. Help, any suggestions?

Craig

 

Have you had the front crank bolt loose for any reason? Also, your gauge should peg to 5bar only on cold start up, and it will not move from that until the car warmns up. After about 20 minutes of driving, the pressure should drop to about 2 bar at idle. At about 3500 rpms, you should be seeing around 4-4.5 bar. You might possibly have a bad OPRV.

 

Thanks! The crank bolt had not been loosened during the maintenance. My mechanic had traced the problem back to the OPRV by the time I contacted him. The valve has been changed and the problem is gone. I appreciate your information, and it gives me a level of confidence in my new mechanic.

Thanks again.

Craig

 

I spoke to soon. I picked up my 944 Friday afternoon (Outside temp around 80 degrees) and had the same issue with the oil pressure gage within ten miles. When I shut the car off and restart the gage operates normally. I noticed that if I increase the rpms slowly that the issue doesn't reoccure until approx. 3200 rpms. If I rev the engine normally the gage acts up at 2100 rpms. This time it seems that there is more noise in the top end when the gage zeros, but it could just be my imagination. The mechanic seems to think that the issue is still somewhere in the OPRV. He replaced the original OPRV with a new updated unit. I returned the car to his shop Saturday morning (Outside temp around 60 degrees) and the problem didn't reoccure on the trip over. (Mostly highway, 70 MPH on both trips) In both cases the engine temperature gage read normally, and the oil pressure gage acted as you described, with the exception of zeroing on Friday afternoon. Ideas?

Thanks,

Craig