Wrong oil pressure sender?

[london96td]

During the past few weeks my oil light and buzzer have been going off when I go above 2K rpm. Prior I replaced the oil pressure sender on the filter part of the motor with one which was recommended by a forum member (White / 1.8Bar)..

The car drove fine without any issues for a while but then the oil light/buzzer sounded, my alternator went... I got the car back yesterday with a fixed alternator and it drove fine without the oil light or buzzer.. but this morning on my way to work the oil light and buzzer came on and kept coming on once I was around 2300rpm. After reading the following..

http://vincewaldon.com/index.php?option=com_content&task=view&id=40&Itemid=28

I realized that I had been advised to use the wrong sensor. I am wondering if I replace it with the Grey .9 bar one from autopartsonlinecanada the light and buzzer would go away.

thank you.

[bajacalal]

They would go away if your issue was that the oil pressure above 2000 RPM (it measures it above a certain RPM) being lower than 1.8 bar but not necessarily low.  

I thought the 0.6 bar sensor went on the head (which is for the minimum oil pressure at idle) and iirc the diesels used a 1.4 bar sensor on the filter flange which is a difference of ~5 psi from the gas 1.8 bar sensor. The polarity between the two on your engine is reversed (one closes, one opens at the required pressure) so you can't mix them up and get a working system. Even though VW only thought a 1.4 bar sensor was necessary, I believe the oil pressure, even on a hydraulic turbo diesel should be at least 1.8 bar ~25 psi at high RPM. I run an upgraded 36mm oil pump and get at least that at idle at the head, on an engine that's getting up there in miles. I get something like 60 psi at 2200 rpm. I just can't see how an engine getting just 25 psi right off the pump is healthy but I guess they did.

Anyway, I think further testing is required, by connecting a mechanical or electrical gauge to your engine. If you're getting less than 1.4 bar (20 psi) at 2200 rpm, your oil pressure is not good. If you're getting less than 1.8 bar at 2200 rpm, your oil pressure is barely adequate. If a gauge shows that your oil pressure is well above 1.8 bar than you have an electrical/wiring problem.

[london96td]

I didn't explain in detail. The oil light and buzzing come on between 2000-2400ish rpm. Then they go both go off as the rpm goes higher or lower.

[london96td]

anyone? now that the forums back up.

[bajacalal]

The buzzer, I think it only operates above 2000 rpm. The system monitors the oil pressure at "idle" and at driving rpm and has there are different values for each and there are two sensors. The "cut-off" point is 2000 rpm. Below this speed it won't sound the buzzer because it's not reading the high-pressure sensor.

So you either have oil pressure that is insufficient or you have the wrong "high" sensor. My guess is that above 2400 rpm the oil pressure increases enough to be within the acceptable range.

What goes on that location is a 1.4 bar sensor, (or 0.9 bars I guess for some cars that we never got here). You never said what kind of car you had. You can put the 0.9 sensor back if you think that's right but I think you should check your oil pressure anyway, with a gauge, to be sure. That is the only way to know what the oil pressure really is because the VW system isn't that reliable, even when it has all the correct components.

You asked if replacing that sensor might stop the buzzer. It might, it might not. Yes, it sounds like you have the "wrong" sensor but you could have an actual oil pressure problem, or you could have a problem with the system (follow the testing procedure on that page).

If you determine that your oil pressure is just barely above what is considered minimum, I would consider trying to fix that because low oil pressure isn't good.

[london96td]

the original oil pressure switch which I removed (threw away) was grey in color.. which is why I believe I either purchased the wrong sender..