Oil Pressure Light

Hi all,

Sorry to start another oil pressure thread.

My car is a standard 1.8 gti. I recently changed the oil and filter using a genuine VW filter and 10w 40 Semi synthetic which is what I have always used.

Upon starting the oil light went out after a few seconds as usual. I turned the car off checked the oil level. Job done.

However, next time I started the car the oil light went out then returned after about 10 seconds. It remained on for about 3 minutes before going out. No buzzer but the engine did not sound happy.

I then changed the pressure sender on the cylinder head. Same problem.

I next checked the pressure with a gauge. It is 5 bar at cold idle and 6 bar at 2000 RPM. This seems quite high and much higher than my Haynes manual suggests.

Finally today I changed the filter in case that was faulty. However, the problem is still there.

Is this oil pressure high ? What could be causing the problem ?

I am thinking of changing the oil pump next but would appreciate any other ideas.

Thanks for your help !

BigMoose

There are 2 times that your oil light will come on.

Low oil pressure at idle when the oil is @ 80c,
Low pressure at high rpm usually above 2000 rpm usually with a Buzzer….. The Circuit board for the low pressure at High RPM is located in the back of the Speedo-housing…



So good grounds or an additional ground wire to the frame at the back of the cluster


For this ground you can use a scotch lok wire splicer.


from frame to Pin2 (brown) is a good Idea, as well as "plumping" up the pad side of your connector with one piece of electrical tape on the plastic tongue of the connector (under the mylar) you have to remove the shroud off the connector and carefully lift the mylar to place the strip of electrical tape on the tongue.




Using the oil pressure gauge is a good thing, but right now without further proof than a electrical gauge I would have the pressure tested with a mechanical gauge.

On a Cabby, you have the pressure gauge and low pressure at idle gauge in a Can that is affixed to the side of the head.  The rating on the gauge is what determines the working pressures of the gauge.

I once bought a cheapie gauge sender off the interweb, it was less than 20 dollars, and found that the gauge was flakier than a Politician.  I then opted for the 70 dollar one and the issues went away.

I don't run Synth oils, and I do run 20w50 and a Wix filter in my ride.  I also have the hi-volume pump installed that has the 36mm gear teeth.

So getting a mechanical test of the working pressures and verifying that your sender can is at the proper working pressures will tell you more.

For a list of proper senders.
http://www.cabby-info.com/electrical.htm#Sensors

Hi all,

Still trying to get to the bottom of my oil pressure light problem. I connected a pressure gauge today to the hole on the cylinder head. Do these pressures seem OK ?

The first is cold at tickover



The second 80C at 2000rpm



Thanks !

BigMoose

BigMoose said

Hi all,

Sorry to start another oil pressure thread.

My car is a standard 1.8 gti. I recently changed the oil and filter using a genuine VW filter and 10w 40 Semi synthetic which is what I have always used.

Upon starting the oil light went out after a few seconds as usual. I turned the car off checked the oil level. Job done.

However, next time I started the car the oil light went out then returned after about 10 seconds. It remained on for about 3 minutes before going out. No buzzer but the engine did not sound happy.

I then changed the pressure sender on the cylinder head. Same problem.

I next checked the pressure with a gauge. It is 5 bar at cold idle and 6 bar at 2000 RPM. This seems quite high and much higher than my Haynes manual suggests.

Finally today I changed the filter in case that was faulty. However, the problem is still there.

Is this oil pressure high ? What could be causing the problem ?

I am thinking of changing the oil pump next but would appreciate any other ideas.

Thanks for your help !

BigMoose

Hi ,
Your pic of the guage at 2k shows a lower psi than I would have thought it should have for those revs. When you say the 'engine didn't sound happy' I wonder if the shortage of oil was seeing the shells pick up?
I had something very similar with my Mk2 Gti last year. I, like you, changed the oil and fitted a genuine VW filter and despite this the oil light refused to go out! when cranked over (always best to pull off dizzy lead and use starter only on oil changes) I changed the filter for another VW one I had-and still no oil light going out. Eventually I unfortunately started it thinking it would do the trick and after about 45 sec it picked up the shells and ruined the engine!!!!
On investigation it seems that because I put the front of the car up on ramps, removed the filter/oil and then left the job for a day , air entered the exit of the oil pump via the filter housing,  and it then did not put out oil as in if you fit a new pump you HAVE to prime the pump to get oil flow. Did you by chance also leave it a while befor fitting the filter?
I remain suspicious of the oil filters though as they were old stock. Have a Mann filter fitted now.
I have used semisynthetic oils for years and years and am sure that that isnt the problem.
I would now drop the sump or at least change the oil (again) and look to see if any metal particles are in it. Also by dropping the sump you can then inspect the oil pump pickup gauze for blockages.
Hope this helps.
Marcus.

The 1.8 at idle is 1.5 bar @ 2000 rpm when the oil is warm.

So I would suspect that you are fine.

My Haynes manual says 2 bar at 80C but this also seems fine ?

note that measuring pressure at the head will give you a lower reading than if you measure at the oil filter housing, this is normal.

in the cylinder head you need to have at the very least 0.3 bar when idling, otherwise the warning light will trigger. if the pressure is too low at the head vs what you see at the oil filter housing this can be down to worn camshaft bearing caps or some kind of issue with oil flow to the head.

at the filter housing when cold the oil pressure will go over 5 bar, then drop to around 1 bar as oil warms up to temp. at revs you want to see the pressure ramp up, at a bare minimum warmed up you need over 1.8 bar at revs otherwise the light+buzzer will trigger

Hi all,

The lockdown has given me the chance to look into this properly. The problem for me was the L-Shaped circuit board behind the speedo as suggested by Briano.



Luckily I had an old set of clocks so swapped the board over and everything is  working good now. I also replaced the dash bulbs so as a bonus now have working dash lights !

If anybody else needs to attempt this it is actually quite easy (I am a muppet with electrics) though fiddly.

Thanks everybody for their help !

BigMoose

good stuff

On a side note, you dont have to take the speedometer face off to swap this board, if you pull the speedometer out the back of the cluster set and carefully remove the blue foil from the back of the speedmeter you can unclip and slip the oil warning board out the side

Good to know. Getting the needle off was tricky.