Oil advice needed please

[Mannings]

Right have a valver with the oil warning buzzer and light coming on when warm (after about 20mins). Not continuous and you can stop it by changing down a gear a little strongly to jolt the engine (nothing too savage of course)

To check the pressure i bought a oil pressure gauge (copper tube one and its a c#nt, but thats a different story). The pressure i'm reading at idle is about 18 psi (1.1 bar appox). This seems low to me, can anyone confirm.
When reved it raises to about 45psi (3 bar approx). This also seems low to me.
Does anyone know what they should run at?

Have done a good flush and new oil + filter already

To sort out the buzzer i have disconnected the wires and earthed the one for the light, whilst leaving the other open which i believe should stop the buzzer going off.

Basically it doesn't. The buzzer and light still come on at the same point, which makes me think its the unit at the back of the clocks.

Can anyone approve my next course of action:

Sack off the unit on the clocks (is this as easy as disconnecting it??) and work off the pressure gauge.
Clean out the oil pick up to improve the oil pressure
And if need be replace the oil pump itself.

Your comments are really welcomed as am driving from essex to brighton in the morning so need to sort it out quick sharp.

Cheers

[herbster]

what oil you put in? 10w30, 5w40?? what?

[Helinut]

I've had a similar problem on a Scirocco I used to have. In my case the previous owner had probably never changed the oil. There was so much crusty carbon deposit on the inside of the engine it started flaking off and blocked the oil pickup at higher revs. Cleaning it all out sorted out the problem. My symptoms though were that the engine was fine until I nailed it. After about 4500rpm the buzzer would come on but would go off again at idle (suppose the flow of oil at lower revs was low enough that the crud wasn't sucked up to the pump inlet).

The correct grade of oil in an engine is extremely important. Check this first.

[Mannings]

Cheers for that.

The oil is correct to haynes manual, 10-40 i think.

Have since got the oil pressure gauge working properly and have identified that there is nothing wrong with the oil system. It hold good pressure through the rev range, averaging about 1.2 bar warm idle and 4 bar @ 4000 rpm which seems about right to me.

Going to just disconnect the buzzer and light from the back of the dials and problem solved

[rubjonny]

1bar at idle is fine, when fully warm mine drops to 0.5bar at idle.  Its had a new oil pump and its a low miler 2.0 bottom end.  The low pressure warning kicks in at idle below 0.3bar, just fyi.

If the buzzer comes on its the high pressure 1.8bar switch triggering it, check the white sensor on the oil filter housing with a yellow wire, pop the boot off and check its got a good connection, if its full of oil you need a new one

[Mannings]

I reckon its not a problem with the sensors as the oil is behaving itself, rather the actual reciever and buzzer in the dashboard.
Apperantly one of the wires only brings on the light (high pressure i think) and one brings on light and buzzer (low pressure). The high pressure one comes on when open so earthing the wire to the battery should stop that one. And then i've been told the second wire closes to set off the buzzer and light, therefore insulating the wire from earth should stop that.

Well i've done this already and it still goes off, buzzer and light the whole time, so was thinking it would actually be a problem with the dashboard unit.

Also as i can monitor oil pressure direct from the gauge and therefore don't need the other warning devices.

[rubjonny]

you're close, its actually the other way round, low pressure switch brings light on at idle, high pressure brings the light & buzzer on over 2k.  If the buzzer comes on BELOW 2k, then its almost deffo the clocks at fault, the oil pressure warning circuit is on the L shaped circuit board clipped to the rear of the speedo, in theory one out of any other MK2 clocks should fit, GTI or carby

[petrolh34d]

I'm having the exact same problem. Did a good engine flush, and this seemed to help a bit, but the buzzer and light still come on when the car is driven hard :S.

My oil pressure guage reads about 4 bar on engine start, but then falls to a constant 2 bar, and stays there until the car is turned off, and cools down sufficiently.

I'm pricing a new oil pump, gaskets, and seals atm and plan to replace all these parts asap.

Is this the correct course of action, or might it be an electrical fault?

[Whaleypete]

Hi,
I have just been having some issues along these lines myself. Mine is a 1991 8 valve.
The low pressure switch on the cylinder head is supposed to open at 0.3 bar. i.e. when the engine is at rest the switch is closed and earthing out. This puts on the red light at low revs.
The other switch on the oil filter housing works the other way round. When there is enough pressure it should close and earth out.
I was driving yeterday and the buzzer and light came on at about 3000 revs. After  a few seconds it all went back to normal. Today I checked the pressure switch on the filter housing using a meter. At low idle it was open circuit. At about 1200 revs it went close circuit and gave the earth. This seems about right to me. The spade end connector on the switch was very jigley and loose so have squeezed it a bit tighter. Test drive was ok.
I checked that the low pressure switch was working by putting the car in gear with the handbrake on and gently lowering the revs by slowly taking my foot off the clutch. In other words trying to stall the engine. The red light started to flicker when the revs dropped to about 700. I am hoping this sounds about right!

[kniterider]

i have an issue with this 16v ive just got, and the oil light dosnt work so need to find out which sensor operates the low pressure light? so i can short to earth and see if the dash bulb is working or the sensor has failed, cant remember which one it is so any pointers?