brucec59

This morning while I was crawling along in traffic, going down a pretty steep hill for several blocks - for at least 6-8 minutes - I felt the engine getting rough, then my oil light came on and my oil pressure was near 0. I gave the throttle a tiny blip or two and the pressure came back up to normal and has been fine since.

After that happened, oil pressure was reading about 1-1/2 bars at idle, close to 5 when moving. Those seem like pretty normal numbers. The engine was warm (about 9 o-clock on the temp guage), plenty of oil.

I don't think it is my sender or guage because I noticed the roughness just before the light came on.

Is this at all normal? Was this caused by going downhill for a long time while idling? Has anyone else experienced this?

Thanks!

ZombiePorsche44

Never experienced that before but it could be that the angle you were on and the oil level being down a bit might have caused the pick up in the bottom to loose suction for a moment causing the momentary loss of pressure.

How was the oil level via dip stick when you got it on flat ground?

ZP44

brucec59

The oil level is fine - about the middle of the guage when warm, which corresponds pretty directly with the dip stick.

2Many Cars

Most likely the engine stumble caused an RPM drop and subsequent oil pressure drop. Your throttle blips got the engine running smoothly and the pressure up to normal. It's basically the same as happens if the engine stalls except this happened in slow motion and you caught it before the stall. The question is what made it stumble. Possibly low fuel or dirt in the tank filter that was moved due to the angle of the car. I wouldn't worry about it.

dhicks

Never experienced this but I would ask how steep a hill were you going down??? AS suggested above it may have been a momentary lack of pressure in the pump and it airlocked or something......as a ref my oil pressure is around 2-3 when hot and idling and when driving it is just over the 5 mark......what oil was your last chnage done with......have you changed from 15/50 to 0/40 and are seeing this for the first time......did you get any code on the OBDII? There must be a guru or two round here that will have the answer

brucec59

The hill is moderately steep, can't give you a grade figure, but it's more than a gradual slope, but not something where they put handrails on the sidewalks (it ws Oak St in SF for the locals). The oil was changed w/ Mobile1 15/50 about 5k miles ago, and I just topped it off last week. No CEL or other lights besides the oil pressure light.

Thanks.

ca993twin

Our cars have a "dry-sump" oiling system to avoid any momentary oil pressure losses when flinging the car around corners or going up or down hills. There is a pump in the bottom of the engine that sends the oil to the big tank. The big tank is used to pressurize the oil system. There should be no circumstances (perhaps upside-down?) that should ever allow an oil pressure loss. Which still leaves you without an explanation. I dunno.

Shaun Leahy

Bruce
I had this in a 964 at the end of a day. Thereafter when slowing down for lights or when the revs dropped, the oil pressure fell like lead below 1 bar and the engine wanted to stall. Both are related. I drove to a 964 specialist who said at first that he had seen it before on a 964 tip which needed a top end rebuild. However....

The problem was the pressure relief valve, think it is on the oil tank which caused pressure to drop, not the volume of oil. Get that cleaned/changed and I hope the problem disappears. Boy was I relieved.
Cheers
Shaun
993 Targa, LPMMs

dhicks

Thats one to keep in the memory banks......

hkate

Has anyone else experienced this downhill / rough engine idle / low oil pressure issue? This has happened to me three times in the past six months. Scary to say the least. Seems odd it would be related to a faulty oil pressure relief valve but I will try it. Any other suggestions?

TIA

pp000830

+1

kevin2012

Sorry to bring this thread back to life. I am experiencing this downhill low oil pressure problem quite often.
May I ask if any of your guys had found the reason?

Could that be possible that because of a weak fuel pump so that the engine hesitates when stopping in front of a traffic light on a downhill and causes the low oil pressure light on?

Thank you very much. I really need some help here.