1989/90 XJ-S: Problem started 2 days ago…cold mornings into mid 20’s at night. Day into the 50’s. Cranked it up this week and the oil pressure gage almost wrapped itself around a second time. Round dial. Pinned at 5 oclock. after a few miles I whammed the dash and the needle dropped back to 3 oclock. but stayed high. Normal is 10 to 2. After stopping and starting around town, all was normal. It is with the cold mornings or going home in the night that I have seen this. Is it a bad sender or in the oil pressure regulator? Will it hurt to drive? No smoke yet and 45 miles each way. Thanks. Harry
I gather this is the later style dash with round gauges? Not the “barrel” gauges?
At some point, Jaguar went with an on/off switch that just stuck the needle in the middle of the gauge if there was any oil pressure at all. I guess that’s an indication of how many customers were complaining of oil pressure issues.
Presuming you still have a real oil pressure sender, admittedly it’s as likely to be the cause of your troubles as a real issue with the oil pressure. I’d suggest that it could also be caused by a grounding issue in the dash cluster, but usually that affects all the gauges, not just one.
If you can find a replacement sender – reportedly tough, as Jaguar wants you to “upgrade” to that switch – it might be worthwhile to just replace it and see if your problem clears up. Confirming that your oil pressure is really that high would presumably involve buying a mechanical oil pressure gauge and screwing it into that plugged third port on the pedestal behind the throttle capstan. If you don’t already have a mechanical oil pressure gauge, easier and cheaper to just buy the new sender.
If it proves to be real pressure spikes, the problem most certainly is in the pressure relief valve which is screwed into the front of the oil filter mounting block and connected to a question-mark-shaped tube that connects back into the sump. Kind of a PITA to get your fingers on, unfortunately; might actually be easier to unbolt the entire filter block from the engine and work on it on the bench. Remember to remove the filter first to give yourself some room in that area. You can screw the old filter back on later if it’s not due for replacement.
Harry, if your low oil pressure warning light stays off, then you might assume you still have adequate pressure even though the oil pressure gauge is not acting right.
It could be a grounding issue, as Kirby pointed out. On my 95 v12 coupe I replaced my oil pressure transducer one time…and the gauge as well… since only the newer style post TSB transducer was available I searched around and found one of the older styles rated 0 to 100psi. Installed it, cranked engine and no pressure. Looked at it and saw I had not connected the wire! Put it on with engine running and checked…now gauge was wrapped round to about 4 or 5 o’clock!
Mistake 1 (I think) was using a transducer that was wasn’t proper for the gauge.
Mistake 2 was making the wiring connection “hot”.
Shut it down and gauge returned to zero. Cranked again and gauge pegged out and stayed. Wouldn’t drop back on it’s own again. So I bought a “used” replacement gauge.
I reverted the transducer back to old one, and still going strong.
A guy I know smart on gauges took his finger and rotated the pegged gauge clockwise back to zero point. Said it would be good again now. I keep it in case needed.
Morale of story is fiddly jaguar electrical. I am hoping your issue is a fiddly ground
Thanks, Kirby and Jim. My 1990 instrument panel came from Texas via a great member for an upgrade years ago. It has round dials and I do not have an oil light. Never got the wiring correct. Thus, it is an analog meter. Not the on/off sender. I appreciate the info on the filter mounting block. I have a book called “XJ-S Aftermarket Parts” that I down loaded a long time ago. I assume it might be part of “The Book” which lists several analog senders. There was a thread about senders many years back with the same info. This book says 100 psi is correct. If anyone else has any info on which one to order it would be greatly appreciated. I have not found a short, but the listed meters meet the qualification. It could be an intermittent short in the pressure sensor. Prices around $12 to 25 U.S.D.
Not to take issue with the purist but changing the instrument panel was one of the 5 best conversion to my Cat…I can see at night. Fantastic…Thanks again. Harry Simmons '90 XJ-S Drop Head Coupe and '48 3.5 Saloon.