Greetings

Long story short - I am once again the proud owner of the car I sold 9 years ago.

However she has come to me with a fresh set of problems.

Biggest of all is the loss of oil pressure. I'm told the needle remains at zero with the occasional flicker of life, the sender unit was swapped with a known working unit which made no difference. I have not seen this myself (above info from the last workshop that worked on her)

Cranking over also presents no rise in oil pressure.

Removing the oil filter and cranking over results in oil pouring out the filter block head.

Can someone shed some light on the oil circuit for me? I understand her to be the "bypass flow" variant. Does the oil filter block contain C37888 or will I only find this valve located on the sandwich plate? How does it differ in function to EAC7149? Am I correct in understanding that EAC7149 controls the oil pressure feed to the engine bearings etc?

Thanks in advance
Nathan

 

You have plenty of oil pressure, do not worry about that! You have a guage that is not rceiving the signal from the sender, or a circuit within the instrument cluster not transmitting current. Various ways to fix this on an XJS V12, see the Great Palm, or the V12 total nerd's 100% cure, done by me recently, see here!!
https://www.jaguarforums.com/forum/x...refurb-296062/
Even though your minor guages are a different design, I expect the same type of fault is the reason the guage is not working. Probably just removing the instruments and cleaning up all the contact points will do it. Once the instrument pack is out, you can also easily test the signal wire for continuity.

 

Before looking for things that rareky/never cause issues, get an Old School mechanical oil pressure gauge, and remove the Idiot Light sender, screw in the Master Gauge, and start er up.

Then methodically trace the dash gauge as Greg stated.

I always use the idiot light port, as it is 1/88BSP, as is standard on most Master Gauges, AND its easier to get at that the gauge unit,

Those valves and stuff, worry not, I have never had issues with them in any V12 over too many years,

 

Jaguar got tired of low oil pressure complaints so the gauge and sender units were redesigned in the 1990s.
Seven PSI was a normal idle pressure but at the dealer we also used 15W40 or 20W50 in all the Jaguars until the AJ8 was introduced.

 

7 PSI at idle does not seem quite enough. After a warm start, my XJ6 is at 40-50 PSI. I'm using 20W-50. Sounds low, although the 12 cyl pumps alot, but 7 PSI seems low. I had that issue on my S3 V12 E-type until I changed the oil, as the oil filter was cloged up and the Relief Valve was dumping open. Ian