Low oil pressure when warm, Crushed. Finally get to drive the car and the idiot light comes on Options

[trojanhorsepower]

A bit of background.
My engine (short block) was assembled wrong by a "professional" about 23 years ago before I got it. When I got it I finished assembling the rest of the motor and found the cam timing was wrong. After several posts and help from Jake Raby we found the cam gear had been installed backwards and a new hole drilled to make it fit. At that point Jake had me split the case, mic the cam and crank and get the numbers off the bearings. All that checked out. I rereassembled the engine and everything went well. Now 23 years later I have the engine in the car and it runs pretty well. (using Brad Penn 30wt break in oil) Except the oil pressure idiot light comes on at idle after the engine warms up. Maybe 10 min of driving. Now based on the threads I have read and the books I have there are no components that affect the oil pressure once the oil is warm? The check valves are for cold oil correct? Hot oil should just bypass the oil pressure bypass valves?
So I will change the oil for 20w50 VR1, but really am I just grasping at straws? What can actually cause this other than bearing wear? An out of spec oil pump? Anything else?

Thanks for the help

Peter

[FlacaProductions]

Are you feeding the idiot light from the stock/oem sender?
Can I assume no other gauges monitoring pressure?

if you're using a two-pole, non-oem sender they can trip at a higher level (8psi) vs. where a normal hot idle is probably anywhere from 1.5-7psi. If you use a VDO 2-Pole Sending Unit, the idiot light is triggered at 8psi, and you will be constantly freaking out at hot idle wondering "what's wrong".

good info here - hoping it's just a case of a sender/gauge issue.

https://vwparts.aircooled.net/VDO-80psi-Oil...m-p/v360006.htm

[trojanhorsepower]

Thanks for the reply. I think it is the stock switch, but I will be trying to asses the actual values. Even 8 psi seems low, what is the acceptable warm idle psi?
the link indicates 1.5 - 7 psi at hot idle, that seems insanely low. IS that really the standard?

[FlacaProductions]

Here's what they say at that link: (but I'm sure the big brains here will weigh in)

We don't feel that the VDO 80psi Oil Pressure, 10 X 1mm, Dual Pole Sending Unit is the "right" sender to use for aircooled VW Engines because the oil light comes on at too high a pressure. Stock is 2psi, this comes on at 7-8psi.
Aircooled VW Engines usually have a hot idle anywhere from 1.5-7psi when properly built (Proper sized pump), and using the correct viscosity oil (10psi/1k RPM hot cruise). More pressure than this at cruise causes the stock oil cooler to be bypassed, and oil temps skyrocket. When you size the pump and oil viscosity properly, you should see hot idle between 1.5-7psi.

If you use a VDO 2-Pole Sending Unit, the idiot light is triggered at 8psi, and you will be constantly freaking out at hot idle wondering "what's wrong".

The solution is to use a VDO 1-Pole Sender with the STOCK Oil Light Switch, to get the use of your Oil Pressure Gauge, with the correct operation of the stock oil pressure switch activating your Warning Light.

Regardless, we are offering this for you enthusiasts that want a high warning light pressure instead of the 2psi stocker.

[trojanhorsepower]

Yeah, I didn't understand that. So basically they are setting this up to come on when the pressure is too high not too low right? At 8psi the light would be on all the time on the low end. And on all the time when the engine is cold on the high end. Clearly I don't understand something.

[emerygt350]

No just when below 8 psi. You should get an oil pressure gauge in there to see what is up. It is still not clear which you have, 2 pole or original?

[FlacaProductions]

Stock comes on lower - two-pole idiot light sender comes on higher. So...if you use a two-pole, you'll see the light more often.

But - since you're using an OEM - AND, IF it IS a sender issue - yours might be bad. I'm just trying to go down this path because it's the easiest/cheapest fix first.

I'd swap that sender.

[BillC]

Perhaps the oil pressure regulator is worn or the spring is tired. You could try installing a Tangerine Racing oil pressure relief valve -- https://tangerineracing.com/shop/ols/produc...re-relief-valve

This can be installed with the engine still in the car.