Oil Pressure warning light

[mikeran]

Once and a while when my son starts the 87 NA the oil pressure light will stay on even though the pressure guage goes up to 5 bar if he turns the car off and restarts it it will usually go out.

Any ideas on what might cause the oil pressure warning light to stick on like that?

He checks the oil all the time and it uses less than .5 quart per 3000 miles. Engine has 198K on it.

Thanks

[exitwound]

The oil pressure sending unit relays to the dashboard. I'd say first clean the contacts on the sender and see what happens. A replacement sender is not very much either. It's located near the passenger side front wheel and very easily replaced. You don't have to drain the oil if you do change it out.

[John_AZ]

Check the brake MC reservoir. Fill to top mark. I had an annoying oil light flicker until I read this curcuit could cause the problem. The other suggestion is only use Mahle or Porsche oil filters, but I'm sure you know that.

John_AZ
1988 924S + 1987 924S

[mikeran]

Yep brake is full, and Mahle Filter on the car, kind of doubt it's the sender since the pressure reading is always working, just the light comes on and stays on until you turn off and restart the car, and like most things it's intermittant so not easy to track down.

But thanks I will try checking the brake circuit electrics and make sure they are working correctly we did change the Clutch and slave cylinders about a month ago. So maybe I bumped something.

[John_AZ]

The wires from the oil pressure sender unit may be brittle because they weave over the WP to the top of the block. The plastic tube covering the wires cracks about 8 to 10 inches from the sender and the wires are exposed to the heat and chemicals. Just a thought.
GL
John_AZ

[mikeran]

If the wires were bad the pressure reading would jump or also fail to read right? The guage works just the light comes on, am I missing something are they different circuits?

[John_AZ]

Originally Posted by mikeran

Once and a while when my son starts the 87 NA the oil pressure light will stay on even though the pressure guage goes up to 5 bar if he turns the car off and restarts it it will usually go out.

If the wires were bad the pressure reading would jump or also fail to read right? The guage works just the light comes on, am I missing something are they different circuits? Thanks

I was thinking it may be an intermittant condition, with the wires rubbing and shorting if the wire protection is decayed.

John_AZ

[Porsche924 mi]

Last night Oil Light was flashing on and off, Oil Pressure gauge was pegged at 5 and stayed there, did not fluctuate with RPM. Restarted engine, light was flashing again.

Let it sit overnight, gauge moves a bit with power on, then pegs at 5 when engine starts, even at idle, light is not on?

Could someone inform me what are the differences in filters, I had the oil and filter change about 3 months ago.

[Stephen03]

Im having the same problem. My sender is ****ed, if I get the oil warm enough and lower the idle by turning electrical stuff on, the guage will read properly (2.5) but anything over that it indicates 5+, must have shorted out inside.

[Porsche924 mi]

Could someone inform me of what the issue is with different oil filters?
I had the oil and filter change about 3 months ago.

[kdjones2000]

The oil sender unit has TWO circuits on it, one for the gauge and another for the light.

You sender unit has most likely failed on you - had the same thing happen to mine, gauge is pegged, light starts to flicker and go on.

Buy a new sender unit and all will be well. As mentioned above they aren't that expensive. You don't have to drain your oil, just unscrew the one in there and quickly replace with new. Done.

Good luck,
Keith