AAZ losing oil pressure?!!

[Torchd]

So I was driving for the at about 120 km/h for almost three hours and all of a sudden the oil light and the buzzer went off and i shat my pants.. pulled over at once and popped the hood.. all was pretty normal and took the oil cap off just to see if the oil was reaching the head and it was but couldn't see much cuz of the baffle.. so I kept driving and it kept on happening even at speeds like 30 kms.

I use fully synthetic mobil 1 or Liquimoly and change was due so I thought oil must have lost its viscosity and therefore the loss is pressure. I got the the oil changed.. mobil1 5W-50 along with the filter and it drove fine until today. It happened at around 50 kms speed and I switch the car off and then restarted and it was fine.


So what is wrong with my car? Any diagnostics I can perform to find the fault? The pressure sensor on the filter flange was leaking a bit so I thought that might be the fault so it was replaced but the problem persists.

Its Golf III AAZ with A/C 1995. I have been using this oil for the last three years 150K kilometers and never had a problem even in really hot temperatures. Ambient temp ranges from -10 to 48 degs.

Does this system warn about high oil temperatures as well?? Cuz my hi speed fans has a problem and some times my car over heats just a bit?  But I don't think they monitor oil temperature?

Please help!!

[vanbcguy]

It only alerts on low pressure...  There is definitely no interaction with the fans, they are just on a simple thermo-switch in the radiator.

I'd highly recommend getting an actual oil pressure gauge right away.  Even a cheap one - just something that actually puts out a number.  You might be fighting a problem with the oil pressure warning system, or you might have an actual oil pressure problem, until you put a gauge on it you won't know.

[Torchd]

Right..

So where does the gauge go? In the filter flange or the side of the head?  And what should the reading be provided the pump is fine?

[vanbcguy]

The side of the head is the best spot, it will always show the lowest pressure as it is fed after the main bearings.  Though in reality you can use either location, just know that the flange is always going to show higher pressure than what is actually getting to your cam.

What pressure you actually see will of course depend on your oil, how hot the engine is, etc.  Generally you should see at least 15 PSI at idle and higher numbers from there as revs increase.  Best bet will be to report back with your findings...

[Otis2]

I believe the Bentley manual says to test the oil pressure at the cylinder head (at the oil pressure switch location). 

At that location, with oil temperature at 80* C (176* F), engine speed 2000 rpm, Bentley says the minimum oil pressure should be 2 bar (28 psi).

I only have my 1.6D Vanagon Bentley handy, and these specs are from that copy.  But I recall the spec is exactly the same for the AAZ (and oddly enough, it's even the same spec for the wasserboxer engines).

[R.O.R-2.0]

2000 rpms is not idle.. i believe anything over about 1 bar is safe @ idle..