Oil Pressure Light and Buzzer

ok pressure looks fine at the filter housing, what was it like at idle cold and fully warmed up at the head and filter carrier?  its normal to see a little pressure drop at the head but you dont want to see it drop too low as that points to worn cam cap bearings.

either way you need the 1.8 bar switch in the filter housing as per OEM for it to be happy

Sorry to interrupt this but can I have a bit of guidance on this too?

Had a new head fitted with a kent gS1 cam. Garage had great difficulty stabilising idle after the vernier set up.

The warm idle is ok and roughly 950-1100rpm.

At cold it is still as low as 400rpm and even needs a touch of throttle sometimes to get firing. I have a feeling this is timing related perhaps, but could it be related to low pressure(?)

I ask because the oil pressure light stays on after a 5 miles of driving. I've had the 0.3 and 1.8 bar switches changed, as well as gaskets and seals of course after the new head. Spark plugs and injectors are new too. 

I released a bit of pressure on the header tank last night too. Silly question but could it have been on too tight(?) the coolant light never came on and the level is about half half way after sustained driving. 

I haven't given her the beans either of course as I'm trying to run the head and camshaft in.

Thanks in advance.

Si

the oil pump is driven from the engine, so if your idle is too low the oil pressure will also be too low. really need the idle to be at least 750rpm to get the light to go off, and if the pump or engine is a bit worn this will reduce the pressure again so you need a higher idle to get the light off.

Oil is thicker cold so the pressure is actually higher at any given rpm than it would be warm, so if the light goes off once car is fully warmed and idle is correct you know the oil pressure system is ok. My MK2 8v had a cylinder head on which had trashed cam cap bearings. the oil pressure light would only come on when hot, even with idle at 900rpm

the coolant system needs to pressurise to stop the coolant boiling, so if you take the cap off on a hot engien you will see pressure release. so its best not to do that if you can help it the cap cant be over-tightened really unless you go mental on it, if you do that you risk damaging the seal, cap or thread and also make it very difficult to remove again

Hi mate,

Thanks

The light is only coming in now after about 10 miles of driving. I'm not ragging it either as I'm trying get the camshaft run in.

The low pressure sensor/switch was a bit loose on inspection yesterday. But even when tightened it to the 'female' the light came on again after about 10 miles. 

There is no buzzing or flashing; but instead the light just comes on feintly then solid red. The new switch I bought is actually on the old/original head… so my last post above is a little inaccurate. Will hopefully grab another new low pressure switch tomorrow, to place on the new head I'm running.

I'm hoping this is just an electrical fault as we know these are temperamental. Do you advise switching/diverting to a set of VDO's instead?


Cheers,

Si

it could be a wiring issue to the clocks also, is it a set of MFA clocks you have or basic ones?

on a side note.

I had a similar issue with my 92.  I ordered a new "sender" and it did similar things.  So I spent the real dollars and got another sender.  It had different things, but still would occasionally flash the light.  

I verified that with the mechanical gauge I didn't have an issue…. So.. I took the Extra Bung out of the oil filter flange and connected the new sender to the oil filter flange… and placed the bung at the head.  

I don't know if it was the sender or the gauge, but I know that since I have moved it, I don't have the issue.

I do know that as a test I placed the original sender on my 93, at the side of the head and had the same issues so I know that the original issue was the sender…

Verify and strengthen the connections on the cluster add (splice) a good frame ground to the brown wire on the connector side.  Plump the mylar to increase pressure on the pins of the connector.

Verify or replace the Battery to frame and Frame to engine grounds, verify that you have all the ground straps on your engine.  Valve cover tin to the Coil mounting bracket….  

Then at least you are at a mechanical issue that you can check with a mechanical gauge, or the warning circuitry in the speedo.

you will usually see lower oil pressure at the head than the filter housing, so be sure to check at the head if you want to see how healthy the engine is.

if your cam caps are worn the pressure can drop low enough to trigger the light at idle when the engine is hot, even though the pressure at the oil filter housing is fine. ask me how I know

so in the short term I did the very same thing, moved my low switch to the filter housing, no more light. pressure at the head, less than 0.3 bar. pressure at filter housing, 1 bar!

VW now sell a 0.24bar switch which replaces the original 0.3 bar switch, so that may help if your head pressure is only just too low

the other thing to note is the low pressure switch earths when pressure is good, so if the path to ground from the oil pressure switch thru the head isnt earthed as well as the oil filter housing, that could also potentially trigger your light....