Druck pressure or lack of… help.

TurboRuf · 08-21-2002, 06:32 AM

In my previous post I described an Oil Pressure concern that I need assistance or advice on. I thought it was important enough to start a separate topic.

When I start my 85 930 the Oil Pressure gauge rises to the top. As the engine warms up it drops rapidly. With the engine hot the needle sits stable around the 2 mark on the Oil Pressure gauge. No matter how much I rev the engine, the gauge does not fluctuate.

I thought this gauge would rise and fall with RPM’s? Since this isn’t occurring what could possible be wrong? Is this an internal engine issue or a sending unit issue? What can I test to pinpoint the problem area?

Keith S · 08-21-2002, 08:18 AM

When you disconnect the sender wire, the gauge should go straight to 'max'. With the ignition off, the gauge should read 'zero'. If the gauge does this OK, then the fault you describe probably lies with the sender unit.

TurboRuf · 08-21-2002, 09:26 AM

Keith,

Thanks, I'll give that a try tonight and report back. Which item is the Pressure Sensor in the diagram... #47 or #28?

Leland Pate · 08-21-2002, 09:32 AM

That would be item #47.

I'd suspect either the sender or the gauge first.

If this turns out not to be your problem... replace the oil pressure relief bypass springs located under the crank case... if the springs are worn out, you'll have pressure issues.

TurboRuf · 08-21-2002, 10:04 AM

Leland,

Thanks for the info.

>I'd suspect either the sender or the gauge first.

I did install a NOS gauge before I put the car back together. I'll toss the old gauge back in tonight for testing. Hopefully it's something that simple.

>If this turns out not to be your problem... replace the oil >pressure relief bypass springs located under the crank case... if >the springs are worn out, you'll have pressure issues.

Overlooked the springs, good suggestion.

TurboRuf · 08-21-2002, 04:04 PM

Leland,

I did some testing tonight and this is what I came up with…

>That would be item #47.
I believe that item #47 is Oil Temperature and #28 is the Pressure Sensor?

I installed the old gauge and it has the same problem, so it's not the gauge.

When I disconnect the green/black wire from the Pressure Sensor, the gauge needle shoots to 5 on the scale.

The strange thing is when I take a meter to the green/black wire up by the gauge, I get readings. When I rev the engine the numbers go up.

So I'm a little stumped. If the pressure sensor is sending a rising signal when I rev, why isn't the gauge reading it? Is it possible that the signal from the sender is to weak?

I also double checked the wiring and everything looked correct.

Jim Sims · 08-21-2002, 05:29 PM

#47 is the oil pressure sender and # 28 is the temperature sender. You may have the wire for oil pressure gage hooked to the oil temperature sender. This would explain the oil pressure gage behavior. Cheers, Jim

TurboRuf · 08-21-2002, 05:48 PM

>#47 is the oil pressure sender and # 28 is the temperature >sender. You may have the wire for oil pressure gage hooked to >the oil temperature sender. This would explain the oil pressure >gage behavior. Cheers, Jim

Jim,

Thanks for the clarification.

I'm sure that's my problem.

Thanks to all for their input.

TurboRuf · 08-21-2002, 06:01 PM

Switched the wires and bingo!

I'm kicking myself, should have made a diagram.

Never overlook the obvious.

Thanks again guys.