Oil pressure gauge variations

[Blaktop]

My factory dash oil pressure gauge seems to have trouble deciding what pressure to show me. I can start it up, run it up to operating temp and the oil gauge shows me one pressure. Then I can turn it off, start it again straight away and it shows a different pressure. There seems to be three different levels it will show......low, acceptable and good. I'd like to think it's a fault in the gauge or the sender unit and (of course) I'd like to think the higher reading is the correct one.

I've had issues in other cars where turning something on or off (like lights) can alter the readings on some electrical gauges but this doesn't seem to be the case here.

Anyone got any ideas? I'm not much chop with electrics.

[4bye4]

If it was a GU like mine I would say an earth problem. Might still be a high resistance joint or dirty connection. Can you see if the needle is bent and touching the glass or backing?

[Winnie]

Yeah those gauges are dodgy as... I would never rely on them.
Mine seems to be fairly accurate comparing it to my after market oil pressure gauge but in my last GQ it was all over the place.

[threedogs]

oil pressure senders in a GU are prone to failure but its just a light on a GU
If its a GQ mudnut may be your man

[the evil twin]

Betcha it's the sender unit.

Notorious for exactly those symptoms

[4bye4]

Betcha it's the sender unit.

Notorious for exactly those symptoms

ET could you check that using 1.5v olt batteries to the meter, ie. 1.5v then 3v then 4.5 etc?

[the evil twin]

ET could you check that using 1.5v olt batteries to the meter, ie. 1.5v then 3v then 4.5 etc?

To test wiring and gauge...
Sender wire connected to sender, ign on, Gauge should read bottom of scale
Sender wire removed and short to earth, ign on, Gauge should read top of scale

[Blaktop]

Cheers guys, I'll have a look at it tomorrow. My pick was the sender unit but I thought I'd ask those with more experience than I....:)

[dom14]

Cheers guys, I'll have a look at it tomorrow. My pick was the sender unit but I thought I'd ask those with more experience than I....:)

If it's a GQ, there's a high probability it's the sender unit. Mine is stuffed as well. I got an after market sender unit with a sandwich plate for the oil filter. I haven't bothered to fit it in yet.
It's still worth testing to make sure the gauge is not faulty as the method indicated by Evil Twin above.
To test the sender unit, you would need a multimeter and check resistance(Patrol manual).
Also, it can be a weak connection as well. See if it gets better when you play with the sender unit wires or when you tap on the gauge window on the dash.

[Patrol'n]

I had exactly the same issue mate, I had mine tested and it was faulty, so I replaced the sender unit and now it works perfectly. That'd be the first thing I'd check for sure


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