XJ 4 litre 1995      .  My gauge was showing a good correct pressure   until suddenly    NO pressure and oil light comes on.         There have also been sudden returns to normal.       Oil level OK and it is clear there is no real drop at all.   What is the trouble? 

Hi

I would get it checked with a oil pressure gauge just to confirm you do have oil pressure

running the engine with out oil pressure will destroy it quite quick

oil pressure sender units are common to fail, but sender and oil pressure switch failing together would be rare

could just be some faulty wiring, but first thing is to confirm you do have oil pressure, by removing the sender for pressure gauge or oil pressure switch and screw a pressure gauge in to double check

Just had a quick google on your car and your car might not have a oil pressure switch, it just has a oil pressure sender, so as this does both pressure and oil light, this has most probably failed and i would replace this first

have also found a wiring diagram if that helps

cheers

Joe

wire diagrams jagxj1995.pdf

There is pressure, the motor would have blown up by now.     No noises, and pleanty of oil in the camshaft box when running as well.     I think the sender is on the right of the filter and could have had the connection  loosened  when I changed the filter.

I think it is actually called a "transducer" , and I see David Manners stocks them.

I need a oil pressure transducer for a 1995 XJS. Not a pressure switch with a resistor. Are there any to be found? Original or aftermarket replacement.

 

Thanks,

Greg K.

1 hour ago, Greg Kacz said:

I need a oil pressure transducer for a 1995 XJS. Not a pressure switch with a resistor. Are there any to be found? Original or aftermarket replacement.

 

Thanks,

Greg K.

hi

might help tell us what engine you have

but have a look on jaguar classics and also look on ebay once you have the part number https://parts.jaguarlandroverclassic.com/parts/index/part/id/C03.910.91012.91012218.910122183984/brand/jaguar/

cheers

Joe

My 1995 XJS is a 4.0 liter six. OEM p/n is LMD5640AB. Replaced with LJM20791 which is nothing more than a switch and a resistor that signals the oil pressure gauge to mid scale regardless of oil pressure, ie: another idiot light.