low oil pressure light

[RabbitJockey]

so i dunno if its actually low pressure or if its the sensors.  but it only comes on at a certain rpm, and only after its warmed up, i read and that seems to be a sign of warn bearings, but the motor has to be really warm like right after i get off the highway and i have a 200 degree thermostat.  so i tried putting a different instrument cluster in to see if maybe mine was faulty, and a spare diesel cluster, and spare gti cluster i had both did the same thing.  the gti cluster was funny to watch the needle bounce around since the tach isn't altered.  now i have hooked up a regular gauge to this before, and revved the motor, and it produced a similar pressure to my dads 85 td, which we checked right after wards, we checked in the head and the filter flange.  i'd like to check again tho just in case.  also i have replaced the oil pressure sensor, my originals were brown and white the new ones were white and blue, i put the blue one in, then put the brown one in.  neither combo made a difference.  is there anything else i should check

[RabbitJockey]

oh come on gentlemen the noise is super annoying

[cyrus #1]

What sort of pressure are you seeing?  The spec is at least 29 psi at 2000 RPM.  If you do have low pressure due to worn bearings you can prolong the inevitable for a while by installing a 36mm oil pump.

Also, what kind of oil and filter are you running?

[RabbitJockey]

its the factory mann filter.  i'll have to hook a mech gauge up again and see.

[RabbitJockey]

ok so there is a relay i wasn't sure if there was or not haha.  i got it pulled out nothing obvious wrong with the pcb on it.[/quote]

[VelocityConservation]

Does anyone have any suggestions for this problem?

What are the correct part numbers for the two oil pressure sensors? (oil filter flange and head for a TD motor).

I am experiencing a similar problem.

Only, mine, the light comes on when oil pressure is above 18psi or  goes below 12psi (based on the reading from my mechanical gauge).

Also using a Mann filter.

Thanks in advance,

VelocityConservation

[Vincent Waldon]

Only, mine, the light comes on when oil pressure is above 18psi or  goes below 12psi (based on the reading from my mechanical gauge).

Some questions to dig in a bit:


Where is your mechanical gauge installed... head or flange ?

Did you tee in to run the mechanical gauge or did you delete one of the sensors ?

When you did your TD swap did you swap the entire engine, or just add the turbo bits ??

[CoolAirVw]

Here's some info in this thread

http://www.vwdieselparts.com/forum/viewtopic.php?t=4923&highlight=

[VelocityConservation]

Vince,

Thanks for the quick response:

My mechanical gauge is Tee'd into the head, so that I retain the original sensor there as well.

I swapped an entire '92 Candian MF engine into my '90 US N/A chassis, but I could not read the part numbers on the oil pressure sensors that originated with the MF engine.

Thanks,

VelocityConservation

[shegel]

you could just remove the fuse if it gets really really annoying.

[gigaz2]

Vince,

Thanks for the quick response:

My mechanical gauge is Tee'd into the head, so that I retain the original sensor there as well.

I swapped an entire '92 Candian MF engine into my '90 US N/A chassis, but I could not read the part numbers on the oil pressure sensors that originated with the MF engine.

Thanks,

VelocityConservation

what car was it from? I can lookup etka.

[VelocityConservation]

gigaz2,

My donor car was a Canadian spec. '92 Jetta

VIN# WVWPH01G6NW075xxx (the stripped chassis has since been crushed)

Thanks,

VelocityConservation

[gigaz2]

there are a few in etka, try to check by their color:
JETTA USA spec:

in the head:
028 919 081D ->  0,25Bar Blue

over fuel filter:
056 919 081E -> 1.8Bar White
068 919 081   -> 1.4Bar Black
068 919 081A -> 0.9Bar Grey


now a 1990 mexican GOLF:

in the head:
028 919 081D ->  0,25Bar Blue

over fuel filter:
056 919 081E -> 1.8Bar White


this includes all engines, its just the etka listing.

[Vincent Waldon]

JETTA USA spec:

in the head:
028 919 081D ->  0,25Bar Blue

over fuel filter:
056 919 081E -> 1.8Bar White
068 919 081   -> 1.4Bar Black
068 919 081A -> 0.9Bar Grey


now a 1990 mexican GOLF:

in the head:
028 919 081D ->  0,25Bar Blue

over fuel filter:
056 919 081E -> 1.8Bar White

Excellent post... thanks for looking up the numbers... gonna write a how-to on all this stuff this summer and I'm gonna steal your work !!

So, to the OP, my thoughts:

Step one would be to confirm that you have the right sensors in the right holes.  The low pressure sensor almost always has a blue body and should be installed in the head.  The high pressure sensor for a 1.6 turbo engine is the 1.4 bar one (the turbo steals a little pressure hence the lower threshhold) and is almost always black... the grey one would work as well.  It's installed on the oil filter flange.

Step two:  confirm that your sensors are working.  The low pressure (blue one) is normally closed and opens when it sees the correct oil pressure.  A test light can confirm that it's grounded with the engine off and opens with the engine at idle.  Conversely the high pressure sensor is normally open and closes when it sees the correct oil pressure... a test light can confirm that it's open with the engine off and closes when the engine generates good pressure (rev to 2000 RPM or better).

Step three: confirm the wiring and warning circuit built into the cluster.  You should be able to make the oil light come on by grounding the wire that goes to the low pressure sensor on the head.  Likewise, you should be able to make the oil pressure light *and* buzzer come on by disconnecting the wire that goes to the high pressure sender on the filter flange and reving the engine beyond 2000 RPM (that's the speed that the cluster starts to pay attention to that particular sensor).

Step four:  if you are all the way to here you may well actually have an oil pressure problem... the spec is 29 psi (2 bar) at the filter flange at 2000 RPM at normal operating temp (rad fan has cycled once)... you'll need to re plumb your current mechanical gauge to the flange temporarily to check this out.

Good luck, and let us know what you find out !!

[VelocityConservation]

Thanks everyone.  I really appreaciate the investigation and solutions you provided.

I will test this weekend and post results on Monday.

The part numbers are important to me because I am color-blind and can't tell the difference between and blue and a black sensor (sort of makes the wiring diagrams tough too).

Thanks again,

VelocityConservation