on my friends 87 190d i recently noticed that oil pressure stays at 3 even with engine warm and 750 rpm,it goes to 0 when key is off.i recently changed oil and filter and am wondering if something may have been done incorrectly to keep oli gauge pegged at 3.i do not know how it was before my oil change as its not my car.runs fine but!!!

Simple troubleshoot. Take an ohmmeter. Disconnect the wire from the electrical oil pressure sendor. Read the ohmage before the engine is started, At idle and at about midrange. All readings should be different.

This does not prove the sendor is functioning in it's correct range though. But at least you know it does vary or change. It could easily be stuck at one value.

For the values you should read on a good sendor you will have to search unless another thread poster knows and posts them. I have in memory the static normal value of a coolant temperature sendor but that does you no good.

I had my cluster out and forgot to reconnect the oil pressure plug back when I reinstalled it. It took me a day or two to realize that the pressure was pegged at 3 no matter the RPM.

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1993 W124 300D 2.5L Turbo, OM602.962
2000 Chevrolet Cavalier, 2.4L DOHC
2002 Ford Explorer, 4.0L SOHC
2005 Toyota Prius, 1.5L

http://www.fuelly.com/sig-us/40601.png

Simple troubleshoot. Take an ohmmeter. Disconnect the wire from the electrical oil pressure sendor. Read the ohmage before the engine is started, At idle and at about midrange. All readings should be different.

This does not prove the sendor is functioning in it's correct range though. But at least you know it does vary or change. It could easily be stuck at one value.

For the values you should read on a good sendor you will have to search unless another thread poster knows them. I have in memory the static normal range value of a coolant temperature sendor but that does you no good.

The going to zero with the key off is really of not much value .All that is occuring then is the circuit is denied operating electricity. I am going a little out on a limb here and can only assume the circuit is electrical on that car. I do not own one.

If the sensor is an open circuit, the gauge will read 3 bar always, including key on - engine off.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

so what im hearing is that this most likely a dysfunction of the gauge electrical or otherwise not something reflecting engine problem?oil flow blockage in filter housing etc.where is sending unit for oil gauge i know rear of gauge has little oil line going to it,but where in engine compatment is sending unit.