1974 XJ12, when I turn the key (but don’t start the engine) the oil pressure gauge slowly rises to the max on the gauge. Same when engine running.

any ideas about what causes this?

I think the oil pressure sender (sensor) is bad (shorted internally) or the wire to the gauge is shorted to ground. If your sender has two wires, one will go to ground and the other (WN in my S3) will go to the gauge. If you have an ohm meter, a good sensor should show 200-300ohm without the engine running. A bad one will show 0-20ohm without the engine running. Check wires from ground to sensor to gauge also. Of course it could be a bad gauge too, I don't have resistance numbers for that though.

Dave

Thanks for insight, though it might've been connector because it worked briefly after i removed and cleaned connector but now im thinking the sender is broken. will report back!

Although my car is lumped, I used the original Jaguar sensor. years back it showed Op that was too low! I knew my Op was OK as the hydaulic lifters were quiet. but, OP is not to be fooled with. I got a NOS unit from David Boger. They are nit very robust.

I tested Op with an after market sun Pro unit. Much more robust. but bbig and a load on th e teeny couplet that concerned. me.

So fa so good. Except I visit my eye doc for another poke in the eye. And another for lab, blood ansd other dtuff. Ugh.

Carl

Andy, with that bit of info, cleaning all the connections and connectors is a must on these cars. Try that again with all in the circuit, might save you a little $$$.

Dave

Carl, it's lucky we can still make blood at our age for all the vials Doctors like to take out of us.

Dave

So true. It was the other stuff that I was short on. First try, Dry did eye stuff and back to the lab. At last. Got some out./ Urine, that is. Shoulkd have had a beer or two before!!!

Suer excercise in the eye clinic. Imaging on bot eyes, Old machine and new one. Plus visual by the eyed doc. unimagined eye contortions involved.

Long sleep and muc better, 13 hours!!! sore yee muscles!!! Anew thing to me!! Vsion a bit hazy yet., Much goop applied there.

But, all is weell, and thankful the great care was available to me at that VA clinic. great folksd. r