Greetings everyone,
My 1992 XJS 5.3L oil pressure gauge is fluctuating when I drive now. Checked oil level and it is fine; no oil leak.
I had a similar problem with my 1993 Daimler Double Six 6.0L and replaced the old unit with one that never fluctuates, but goes to the mid point of the gauge. Since replacement, its never been a problem.
Is there such a "fix" for the XJS?
Or, do I just replace C46272 with an aftermarket model? (I doubt the original has ever been replaced)
Is there another oil switch that people would recommend to be changed at the same time? If so, please provide the part number.
Many thanks,
Charles

 

Charles,

Jaguar brought out a new sender unit in the 90s, apparently because US owners complained that the pressure gauge fluctuated (as indeed it should at times!). The new sender unit acts really as an on/off switch. If you’ve got any real pressure, the gauge just sits in the middle. It’s not ideal for those of us who really want to know an accurate pressure reading, but it obviously kept the bulk of customers happy (and ignorant of the real pressure!).

AFAIK, the part number remained the same. I still have the original on my 4.0 AJ16 and although the gauges are never that accurate, I'm quite happy seeing it go up and down depending on temperature and revs.

Cheers

Paul

 

It's entirely normal for the gauge to fluctuate. It'll be fairly high when the engine is cold. Once warmed up, the idle pressure will be low, and increase as engine RPM increases. Just note what is normal. As was stated, some dealers just installed a switch, so the gauge read mid-range if there was any pressure at all. That'll give you no indication of what the real oil pressure is.
Jon

 

Are you saying it fluctuates as you hold a speed and rpm on the highway? Like you're cruising at 2000 RPM and the oil psi indicator is going up and down? Or do you mean when you start it it is one reading, once it's warm its another, and then idle vs at speed is different?

 

Once warm, at a given constant rpm, oul pressure should be constant. It will fluctuate with RPM. It will lag a bit as RPM changes, that is, the change in pressure won't be instant.
Jon

 

Greetings. It fluctuates while holding speed, and at idle. It's all over the place.

 

In that case, I'd suspect a loose connector, frayed wire, or a bad connection at the gauge. Bad senders normally don't do that.

 

I would agree. Does the gauge completely bottom out or top out?

 

Things we got when I worked at the dealer.

 

I think he's suffering a different issue. Oil viscosity should not cause the gauge to fluctuate at a constant RPM.
Jon

 

Change the sender, check the wire for continuity.