I’m still having an oil pressure warning light issue. 3 seconds after starting the car until I turn it off the “!” light is blinking.

After reading similar posts I’ve changed the sensor, checked the connectivity, but still the blinking light. My current fear is that I truly have low oil pressure, although the gauge reads 2 and up.

Is it likely the idiot light is correct & the gauge is wrong? Is there a way of confirming I don’t have low pressure? Outside of noisy lifters (which are no louder then before the !) what are the other indicators of low oil pressure? Does anyone have an external gauge that they are willing to loan out ?

 

Not sure how the '85 dash alarms read - but the '!' may be linked to the oil level sensor: If the oil level is OK, check out the wire leading to the front of the pan (near the alternator). At correct level, the ball float (like a toilet tank ) keeps the circuit open: when level falls, the wire is switched to ground. With a meter, you can quickly check both switch and wire.

 

Greggles,

If you go to AutoZone or similar, you can buy a simple mechanical oil pressure gauge pretty cheaply. They use nylon (??plastic) tubing of very small diameter to plumb to an actual oil galley. Don't worry about the plastic tube, or the weak-looking connectors... they're fine, really. The surface areas are so small that the total pressures are very, very low.


Anyhow, get one that's mechanical (versus electric, with a sensor like the stock one), mechanical gauges have a 270degree sweep, versus 90deg.

Plumb it in, and check out the readings. You don't have to leave it, but it might be worthwhile to temporarily mount the gauge in the car and go for a drive.

It should cost around $30.

aaron

 

Thanks for the replies

Aaron - I'm sure you can understand my reservation in snaking some tubing through a running engine. Where would I put it in and where is a good place to get a reading? The other guages that I've seen screw into an existing port.

Garth - After reading the wire diagram I'm puzzled. The sensor has 2 contacts (on bottom); one is the oil level and the other oil pressure & ground is through the block? There is connectivity between the 2 contacts on both the old & new one. Is there some internal relay? The more I think about it the more confused I become....uggggh

 

Two different 'transducers': . The sensor with 2 wires beside the oil filter is the pressure transducer. On early cars, one wire is ground - the other signal to the pod cluster - at year 'X' ( which may include the early 32v), IIRC, the sensor is grounded through the engine as you noted - and the two wires send signals to the pressure gauge and to the low pressure alarm: A voice of experience will be needed to indicate which one you have in an '85.
What I referred to was that odd flange mounted single wire sensor in the very top left front of the oil pan - which indicates low level at ~ 6.5l when the ball float drops into its cup, grounding the signal wire.

 

Greggles...

First off, i admit that i've owned my 928 for all of a week now.... so, i have no idea what i'm talking about with regard to the 928 engine specifically....

BUT.... the current sensor (can thing with two wires, as described to me) is already screwed into an oil galley.... unscrew it (engine OFF, of course) and replace it with the mechanical (therefore simple, reliable and verifiable) gauge.... the pipe-thread port is generally of standard size (this is where my non-Porsche-specific-knowledge-caveat applies... you may need an adapter)

Or, even better, use a brass "T" connection (these will probably be sold alongside or even with the gauge itself) and leave both your original sensor and the mech gauge connected at the same time.

Doing this will certainly tell you what the actual oil pressure is in your engine, at least at that point in that galley..... note that oil pressures can vary in different places (ie the 2/6 main bearing, which i understand has weak oiling in these motors), but you will 100% for sure get a good comparison against your stock dashboard gauge.

For the record, the oil gauge in my car is really, really wonky too.... it bounces wildly, and has slipped down to almost nothing (not dead, just almost), and then later returned to bouncy life.....

aaron

 

Mine is horrible. One day while driving, it randomly went to zero and the light began flashing. I was very afraid, but then realized that all the temps were perfectly fine, car ran great, there was oil in the pan... so I drove it home and have been driving like this for a little while now.

I replaced the sensor with a new one, and its constantly acting crazy now. I tried swapping the wires (just in case i mixed it up when i put it back in) and now I get a zero reading... so thats probably wrong.

My guess is that theres something wrong where the sensor connects to the gauge.

Does anyone know if the sensor connects DIRECTLY to the dash pod? Or does it go through any sort of processing/computer system?

sorry to jack the thread, but i think this is info we all can use.

 

On the 85 US (+86?) both wires from the pressure sensor go to the pod. One connection goes through the central warning unit and the other directly to the pod.