Oil Light and Buzzer

[Freddievan]

1991 petrol 1915cc

A couple of weeks ago the oil light and alarm came on whilst driving  - short journey.  I panicked and put a litre of oil in it when I got home.  Seemed to have done the job.  However, had the same issue today.  Short journey, around 6-8 miles.  

Light and alarm came on then went off again and this happened intermittently for the final 4 mile of the journey home.  It did gradually get worse as I went on.

Checked oil and level seems fine.

 

[Freddievan]

Just to expand this a little.  The problem has arisen when the van has warmed up.  Both times after around 20 mins or 5-6 miles.  I've been driving it pretty regularly in between alert incidences but only to work which is less that 3 mile journey.

Also, I used a different type of oil last time I topped up.  Same 15w-40 grade but I don't think it's mineral.  Not sure in this would affect anything?

The van has always leaked oil but doesn't seem to be any worse than usual.

[Aidan]

so check security of connector at the dash to ensure tacho signal is getting to the bod circuit and do a wet oil pressure test to check that the oil pressure when hot is actually okay so you can safely ignore bod
which high pressure switch have you got fitted the original white 1.8 bar one or the 'its a tired old thing' VW bodge to shut the bod up 0.9bar grey one ?
and check the wiring is all good

[Freddievan]

so check security of connector at the dash to ensure tacho signal is getting to the bod circuit and do a wet oil pressure test to check that the oil pressure when hot is actually okay so you can safely ignore bod
which high pressure switch have you got fitted the original white 1.8 bar one or the 'its a tired old thing' VW bodge to shut the bod up 0.9bar grey one ?
and check the wiring is all good

Thanks for this, Aidan.  I think I misread this initially and have sent for a white switch.  Are you saying it may be better to fit the grey one?

[Aidan]

originally VW fitted the white one to the WBX, new engines or well maintained ones would easily have enough pressure to make 1.8 bar or more at 2000rpm, just under 1 bar at idle ramping up quickly - if you fitted a gauge you might see 3+ bar at 3000rpm even when hot (4-5bar cold)
As the vans aged or when they weren't well maintained VW dealers/garages would have been plagued with customers with b.o.d issues - the simple solution was the grey 0.9bar switch as fitted to the diesels which tended to be less well maintained and/or harder on their oil - result was customer was happy the buzzer wasn't going off and the garages happy they weren't having to replace engines
which is why I recommend a proper hot wet oil pressure check, but I appreciate many people don't want the bother of that and don't really care if the engine is tired and the oil pressure is low, when vans were cheap and used engines readily available you could just run it till it broke - now it is hard to find a reputable rebuilt engine so knowing if the engine is in less than ideal shape could be a mixed blessing

[Freddievan]

it is hard to find a reputable rebuilt engine so knowing if the engine is in less than ideal shape could be a mixed blessing

Obviously, engine rebuild/replacement could be the outcome    Are they really difficult to find?  Possibly start a new thread for this one 
 

[Freddievan]

Mechanic has fitted new switch but this has created a different oil light issue.  When engine is started up the oil light starts to flash intermittently at regular intervals - like an indicator light.  No buzzer.  I drove the van home and as the engine started to warm up the light only flashed when I accelerated.

Mechanic doesn't have a pressure gauge to do a wet oil pressure test.  I'll contact auto-electrician to check all connections and research if anyone local can do a wet oil pressure test.

[Aidan]

so does the oil light come on when the ignition is switched on ?

and then go out when the engine starts ?

[Freddievan]

so does the oil light come on when the ignition is switched on ?

and then go out when the engine starts ?

No, the oil light comes on (flashing on and off) as soon as the engine is started from cold.

[Aidan]

sounds like a wiring issue to the bod circuit

[Freddievan]

sounds like a wiring issue to the bod circuit

Fingers crossed 

[Robsey]

My brain having a silly thought...

Has the garage replaced the low oil pressure switch with a high pressure switch.?

From memory one open-circuits under pressure,
The other closes / shorts out under pressure.

The fact that it is flagging a low pressure fault when the engine revs increases, points me to think that way.

-
Does anyone else agree, or am I being daft?

[Aidan]

I'm thinking they swapped over the wiring for the two switches, same result
but you might be right

[Mocki]

Reading through this , first thing that calls out to me is mixing mineral and synthetic will do no favors ……
secondly , the low pressure light only comes on above 2000 rpm , and in the first instances when engine is up to temp and after slowing from a warm run. 

[Freddievan]

Thanks all.  Someone is going to do a wet oil pressure test next week.  I'll ask him to look at the wiring.  

Will it be an idea to change oil because I mixed in some synthetic?