PeteL

OK, I have chased gremlins over the last 7 years and have the car where I am now attacking minor annoyances. Since the day I have owned this car, the oil pressure gauge pegs at the high end as soon as I turn the key. The warning light does not come on.
Where do I begin on this one?

Porsche-O-Phile

Pull the dash cluster and clean all the contacts with alcohol. While you're there check the bulbs and the "metalized" crap on the light tunnels.

Mighty Shilling

Oil pressure releif valve? Just a geuss...

KuHL 951

The OPRV would not effect the gauge until the motor was actually running. A pegged meter at 'key on' is can be a bad ground, bad sending unit, or swapped leads at the sending unit. Does the gauge act normal after the car starts or does it stay pegged all the time?

johnny1423

its a bad oil pressure sending unit....$60 in catalog

Mighty Shilling

ah. good call...I misunderstood...thought it was running, and wondering how the hell he pulled off driving the car for 7 years witha bad OPRV... that cylinder head would be TOAST!

clangjr

This is a somehwat similar situation so I figured I'd ask in here....what is the normal operation of the oil pressure gauge when running? Where should it be at idle? Where should it be when cruising? Where should it be when you're getting on it?

HY M8NC

Agree, bad sender. When they fail, they peg. Normal oil pressure at idle is between 2-3 bar, rising by 1 bar per 1000rpm to a max just under 5bar-iirc.

The sender is actually 2 sensors. One for the idiot light, and one for the gauge.

jonnybgood

Yeah, I just had this problem. Traced signals for days on the instrument cluster. Pulled it at least 5 times. Replaced the 1N4004 diodes that drive some of the warning lights. Cleaned all the contacts as mentioned on Pelican. But refused to replace the oil sending unit that I had already purchased because it "had" to be in the cluster.

Finally replaced the oil pressure sensor and everything worked fine. There is a write up on testing and replacement on Clarks. The sensor provides ground for some of your warning lights, oil and volts, before starting and then when pressurized by oil flow turns them off.

clangjr-read your owners manual it has a good description of what to expect. My oil pressure readings have now all dropped since I cleaned all the contacts on my instrument cluster. 1.5 at idle and 4 at speed used to be 2-3 at idle and close to 5 at speed.

joseph mitro

that's what mine reads on a fresh engine rebuild with dino oil (10-W40). i was thinking that maybe i reinstalled the gauge needle slightly off since i have swapped the gauge faces twice (first to white, then back to black)

clangjr

Mine reads 2 at idle, just under 5 at full boost, and fluctuates inbetween when driving depending on how sprited my driving is....so I guess I am pretty much normal. Someone told me it was screwed up once.
Chuck

gtroth

Bad sender, bad gauge, or both (like mine).

PeteL

I am leaning towards bad sender. Is it a big job?

GlenL

Swap the leads before going for the new sensor. You may be pleasantly surprised.

PeteL

I thought the leads were keyed by size. Will have to take another look.