Oil Pressure Gauge At Constant Max

[rbdemen 1]

My oil pressure gauge needle goes straight to the right as soon as a turn the key and stays there until I shut the car off.. I thought this was a good thing, but soon realized after reading through some posts on the forum that it should fluctuate depending on engine temperature and RPMs. Do I have a problem on my hands? Bad oil pressure sensor? Car is a 1990 1.9 GTI unmodified and runs beautifully, albeit has some mysterious oil consumption (no visible leaks or smoking).

[welshpug 1,622]

sounds like a short to earth, check the wiring.

[Bakes100 20 1 Cars]

Does it only go to max with the car running? Or is at max with the ignition on the 2nd click?

[rbdemen 1]

Oil pressure gauge goes to max at 1st key position. Which earth?

[jackherer 543]

The car body and the engine block are both connected to earth so if the wire has become damaged and is touching the engine/gearbox/body anywhere it will make the gauge go to full deflection.

 

Find the oil pressure sender (under the inlet manifold) and follow the wire back until you find anything suspicious.

[Miles 331 1 Cars]

Could be the wires crossed over when someone's been under the inlet manifold, Thats normally the issue

[rbdemen 1]

Could be the wires crossed over when someone's been under the inlet manifold, Thats normally the issue

When you say "normally the issue", you mean this is a common occurence? How do I fix this? Is it that the connections for the oil pressure sensor and the sender are reversed? or the wires themselves are touching and should be insulated from one another?

[Mikey S 29 1 Cars]

Oil pressure switch wire has been put on the pressure sensor and vise versa. Try switching the wires around and see what happens.

[jackherer 543]

From your posts it sounds like the gauge goes to max when you turn the key on AND stays at max while the engine is running?

 

If that is right then the problem isn't those two wires being swapped over, that isn't how it behaves when that has been done, the gauge goes to max when the key is turned then goes to zero when the engine runs.

 

Does the oil pressure warning light and STOP light behave correctly? I.e. do they come on when you turn the key on and go off when you start the engine?

[rbdemen 1]

Oil pressure switch wire has been put on the pressure sensor and vise versa. Try switching the wires around and see what happens.

Mikey S thanks for the suggestion. I did like u said and switched the connections from the sender to the sensor and vice versa. When I turned the key, the oil pressure gauge stayed at zero. When I went for a spin around the parking lot, I noticed the STOP light glowing faintly. So I switched the wires back the way I found them. Back to square one.

[rbdemen 1]

From your posts it sounds like the gauge goes to max when you turn the key on AND stays at max while the engine is running?

 

If that is right then the problem isn't those two wires being swapped over, that isn't how it behaves when that has been done, the gauge goes to max when the key is turned then goes to zero when the engine runs.

 

Does the oil pressure warning light and STOP light behave correctly? I.e. do they come on when you turn the key on and go off when you start the engine?

jackherer yes the gauge stays maxed with the key on and while the engine is running. The oil pressure warning light and he STOP light behave normally. In fact I thought all was well til I realized the pressure gauge was supposed to fluctuate.

[toolie72 67 1 Cars]

Has to be wiring rather than mechanical-it wouldn't go to max BEFORE engine starts if it was mechanical

 

An old school test to check gauges was to put the spade connector onto the engine-if gauge read max, gauge was ok

Somewhere you have a bare wire touching earth, in effect replicating that test

 

The oil pressure gauges are only an indicator anyway, you can swap gauges and have completely different readings on the same engine!!

[jackherer 543]

jackherer yes the gauge stays maxed with the key on and while the engine is running. The oil pressure warning light and he STOP light behave normally. In fact I thought all was well til I realized the pressure gauge was supposed to fluctuate.

 

 

If the light works correctly the wires are 100% not swapped over and you can be sure your oil pressure is OK.

 

Like I said before locate the sender under the inlet manifold (the larger of the two near the alternator) then follow the wire back over towards the gearbox checking for damage.

[Miles 331 1 Cars]

If the stop light is glowing than that's not too bad when the engine get's warmer as the oil pressure drop's, Sounds like the sender is faulty, if it was a wire if swapped over the short would still be there