Mc.Queen 964

Hi guys,

My car, in D, at service temp or more, always switch on the oil pressure light. If for example I put it in N light switch off. I know that gearbox stucks a bit the engine and for this cause light switch on at idle on D (with brake pushed).

Any solution?

In this pic I show my oil pressure, when ir runs it go perfect, 3000 rpm 4,5 bar +-.

My oil is castrol 5w40.

braol

Check leakage at oil pressure sensor.

Mc.Queen 964

I changed the oil sensor 2 years ago. No leaks.

Regards.

braol

Well, without any visible oil leaks I would expect either an oil pressure relief spring is faulty or your main bearings are worn.

Mc.Queen 964

Braol, I'm spanish and I don't understand so much what is a oil pressure relief spring or a main bearing. These are parts of the oil sensor? Are they easy to fix?.

I have to say that with REPSOL oil that only happens when the car was REALLY HOT, not like now. So.. ??

Silvertarga

I dont run 5 or 10 w oil in warm weather, try going to 20/50..

Oil pressure relief spring isnt a big deal.

main bearing...I dont want to be the one to give you the bad news

Mc.Queen 964

I turn the car on, and in N, HOT (9:00) I've got 0,6-0,7 BAR at 950 RPM (NO LIGHT PROBLEM), when I put D with brake pushed, RPM's go to 790 and oil pressure to 0,4 BAR (LIGHT SWITCH ON), If I put again N, Light switch off again.

What is normal pressure for a 964 HOT (9:00) at idle? With 5w40 REPSOL that doesn't happens until oil temperature goes to (9:00) or more, now happens from 8:30 +-.

Regards.

crg53

I use Brad Penn 20W-50 and when at operating temp at 840rpm idle, the gauge shows 2 bar, at 3000 rpm it is just under 5 bar, and at 5000 rpm it is 5 bar.

DaveK

Oil pressure in 964s seems to vary plenty between cars. Mine is one of the lower ones - usually about 1 bar when warm, and I occasionally see the oil light if the revs drop as I'm pulling away (manual car).

It could be that you have a dodgy oil pressure sensor, or it could be a more serious problem. I'd try replacing the sensor first though.

Mc.Queen 964

I will change relif spring and relif valve. I hope it work.

IT ONLY APPEARS (LIGHT) WHEN I BREAK, and it dissapear at idle, only shows the light with D gear. But really hot, with N, 0,6/0,7, which is low...

I hope that work.

altarchsa

+1

You didn't mention the mileage on your car, but most of our old cars are high mileage and oil pressure is lower, especially at low rpm, due to the spaces between wear parts being greater. Even on a rebuilt engine, if you haven't replaced every single wear part with oil passages, the oil pressure will be lower.

If you don't have a less-than-50K mile engine, you're compounding the problem IMO by using too low of a viscosity oil. It's hot here in Texas, so I use a heavier oil, but I think most anywhere in the US a 20W-50 oil would be more appropriate in a high mileage engine in summer. If you have a high mile engine, I would bet that your oil pressure issues will disappear with some 20W-50, and engine protection will not be compromised.

Mc.Queen 964

My car has 91k milles, I live in Tenerife, an small island with about 20-25º, no cold winter (17-18º), Should I put 20w50? Or change Valve relief and spring relief and continue with 5w40?

I think I will try to change valve and spring relief, after, if it doesn't work.. 20w50..?? What do you think?

crg53

I would change the oil to something like a 20W-50 first, that may fix your problem.

Mc.Queen 964

Thanks crg53, tomorrow I will go to my porsche dealer to talk with the aircooled mechanic.

I think I can't sleep tonight... pff

Mc.Queen 964

Another question.. Should I change Valve or Spring relief? I think that Spring is when I've got overpression.. that's right?