Seems like my oil pressure gauge has lost its mind. A few months ago, it was reading really slow, so I replaced the sender. Worked perfect until yesterday. It sort of lays dead, then comes up to snuff with a little revving. Holds fine until I let off the gas then drops right to below zero. At idle its either completely dead or shaking rapidly.

I'm posting because my first instinct would be the sender, however, that was replaced. Pulled the tach out to wiggle some wiring behind the gauge, but that did nothing.

Any quick thoughts??

I attached a quick video to show it in action.

 

Sure!

It's either the gauge, the sender, or the wiring. Does that help?

Well, ya gotta start somewhere. I'd begin by checking the wiring at the sender. That section of wiring takes a beating from engine heat.

If that doesn't pan out, and since your dash wires pass the wiggle test, I'd guess your sending already went T.U.

Cheers
DD

 

I read somewhere to test the gauge by jumping the sender wire to ground, turn ignition on and verify pressure gauge goes to max. Sound right?

 

Right!

In your case I'd jiggle the wire a bit to see if the needle goes wonky during the test

Cheers
DD

 

Verified the gauge was working based on the above test, went right to full pressure no hesitation. All signs point to a troubled oil sender unless you all think I should test something else. Only about six months old from SNG Barratt...I guess I'll see if it's a warranty item.

 

Some time back, the OP guage on my lump acted similarly. I sought a mechanical guage to assuage my angst, although I was reasonably sure that OP was present. No luck at the auto parts shop. The added guages and plastic line of past years are gone. But, I did chose a Sun Pro
electric guage kit. I plumbed in it's sender and hooked up the electrics. OP present and healthy. It's sender has two positions. One matched and the OP read about the same as the Jaguar unit when it was still OK. I got a NOS sender from David Boger and all has been well in that area since.


I did note that the Sun Pro sender is larger and seems of higher quality.


So, the Sun Pro unit is my tool box as a diagnostic tool and a possible replacement if the Jag sender goes bonkers. It will, it is just a matter of whether it matters to me or not!!


Carl

 

Between the tach and speedo inside dash is a voltage regulator for the gauges, might check it out as I see your voltage is a little low for idle and revs.

 

Or, the voltmeter s just doing it's thing, slow reacting. It reads gross
volts, sans any adjustment for the gauges.


I was alarmed about that at one time on my car. so, I made a patch cord and read volts on my VOM via the cigar lighter. Real time volts under various load and rpm's via a better instrument. All was fine.


Carl

 

Just so thedugger doesn't end up scratching his head needlessly....

That instrument voltage regulator was not used on the Series IIIs.


Cheers
DD

 

Carl, Why did you not use the sender that matches the JAG gauge,..ie the stock JAG sender ?

 

Alyn:


I did. The one on the car is the NOS replacement I got via David
Boger.


On the install of the LT1, I transferred the Jag sensor from the ailing 4.2. it worked just fine for a while....


So, the Sun Pro was in lieu of a capillary after market guage to check oil pressure.


After verifying OP was great, I got the one from Dave.


All is well, til next time....


Carl

 

That voltmeter reads low. I had battery and alternator tested and everything was up to snuff. I understand that you can adjust the gauge, but that's "currently" low on the to-do list (pun intended :-)).

 

FINALLY got this sorted. It was the oil pressure sender. Was an easy replacement. Did from below by feel, no jack necessary. I found removing the assembly the sender was attached to made it easy. 19mm, then once out, remove the sender...18mm if I recall. Just keep an eye out for the three copper washers.

Still a surprised the Motorcars LTD unit lasted only 6 months. Out of warranty, but I'll let them know any way in case I'm the only one.