Oil pressure

I bought an oil pressure gauge from Volvo to fit in my instrument cluster. It seems to work fine but the needle always goes all the way over the scale (which is from 0-5 bar) and stay there, even with the engine switch off. Have I done something wrong? What could cause this?

George

'87 745 GLE Turbodiesel Intercooler
'89 440 GL 1.7

[Peter Milnes]

Is the oil pressure gauge electronic or pressure operated? If electronic ensure that the correct sensor is fitted to the correct sensing point, there may be some calibration required or the sensor may not be correct for your car.

If it is of the direct pressure operated type then you may need to bleed the connecting pipe and place the connector in the correct place. I would suggest a tee piece on the turbo oil feed pipe attachment hole.

Do let me know what type you have and hope you can sort it. Remember that a Volvo (Mann) oil filter has a pressure hold facility when the engine is not turning which influences your choice of pressure take-off point.

All the best, Peter.

Well, the type I bought came with a sensor that replaces the original one in the middle of the block on the glow plug side. You remove that one and screw in the new one which has two connectors, one for the old wire and one for the new wire, the new wire you run to the gauge, which also has a power taken from the cluster itself and then one wire to an earth point. It did say use earth on fuse board but I used a different earth point, but that should not make a difference, should it?

George

'87 745 GLE Turbodiesel Intercooler
'89 440 GL 1.7

[Peter Milnes]

Did the instructions make any mention of an Instrument supply? It is possible that the one you bought is designed to go with a regulated instrument supply. If that supply is, say, 6 Volts, then you will need to buy or build a suitable voltage regulator to run the instrument circuit from. The wiring should be from the regulated supply to the instrument, then from the other side of the instrument to the new connection on the two connector sensor. This is the circuit for reading the oil pressure. The other connector on the sensor should be a pressure switch which open circuits when the pressure exceeds the minimum safe running pressure for the engine. This one operates the oil pressure light on the instrument panel.

Let me know if you cannot get it to work. Attach a copy of the instructions in an e-mail direct to me, and I will see what can be done to get it working for you.

All the best, Peter.

I plugged the supply wire to a female blade connector on the cluster as per instructions. It says 12 volt on the gauge, I think. I followed the instructions precisely . I suppose something might be broken. What is a normal oil pressure anyway?

George

'87 745 GLE Turbodiesel Intercooler
'89 440 GL 1.7