All, this is firmly in the vein of a "newbie" question, so my apologies. I did search, but couldn't find (at first blush) what I hoped to find.

Today I drove a V12 Jag for the first time ever. Car started up well, is in very good condition physically, 74k mi, but has a few problems (A/C not cooling, Cruise inop, slight leak at windshield seal, and a possible fuel leak) that are all manageable.

What concerned me was oil pressure.

The car was fully warmed up, and had an oil change done 7/21/19 (5W30). At idle, there was *no* indication of oil pressure (but, in retrospect, there were no warning lights, either).

Racing the engine to 2000 - 2500 rpm gave an indication of perhaps 30psi.

Is that normal? It didn't seem normal to me, and as a result I walked away from the car. If this is all 'normal' Jag V12 behavior, I'll call the guy back tonight, but I need your expertise to convince me....

Thanks!

Brad

 

Normal.

The V12s have very low pressure at idle, maybe 5 psi. And the gauges are not very accurate, to boot.

Using the rule of thumb 10 psi for every 1000 rpm, your observation of 30 psi @2500 rpm sounds OK. I think the spec is 40 psi at 3000 rpm but don't take that to the bank.

The V12s very seldom suffer oiling problems or problem with the reciprocating assembly. 'Tis the cooling system that you have be extra careful about....as the end result of neglect or incorrect repair can be dropped valve seats.

If you buy the car make sure to post back. There are some 'must do' items that a new XJS owner may not be aware of.

Cheers
DD

 

DD,

Thanks for that reply. It was a hot day, and the temperature gauge was rock-solid right in the middle....so engine temp seems not to be a problem.

Everything else about this car was minor, it was just the pressure that was of concern to me....

 

Your running some light oil, specs usually say 20w50 if Im not mistaken.. Not sure I want to start another oil war but I run Delo and its great.

 

We used Mobil 15w40 at the Jaguar dealer for all the V12 and straight six cars!!

bob

 

Mobil?! This. Means. War.

 

War! Because the best oil money can buy in the US is Amsoil. There you have it. Amen.

 

Amsoil is good, worth getting a member wholesale account.

 

Spew. the only good oil is Castrol GTX 20W50.

 

i run mine on WD40. Are the pistons supposed to poke out the side of the block??

 

DD,

Posting back, as recommended. I *did* buy the car. Drove it back from Raleigh, NC to Richmond, VA (3h highway drive) without any problems whatsoever. Promptly left on holiday, so I haven’t tinkered any (yet).

Could you give me the “Must do” list please? Headed home today, and I’m definitely ready to dig in!!

Brad

 

Brad,

Congrats on the purchase of the car! You're going to love owning a Jaguar V12!

As part of you list of jobs, you really must attend to that "slight leak at windshield". XJSs are notorious for this issue and nearly always means that there is nasty corrosion in the windscreen frame. If left unchecked, this goes into the scuttle and the inner wing. So please do have a look at it urgently!

Enjoy the car!

Good luck

Paul

 

Paul,

We traveled through significant rain on the trip home (on the highway) and I didn’t see any leakage. Not saying it won’t happen, but I don’t think it is Job #1. The material condition of the rest of the car makes a corrosion issue like you’re describing very unlikely (yet).


Brad

 

Ignition:
Since your XJS has Marelli ignition you'll want to make sure it's in good shape....or bad things can happen.

At minimum remove the distributor cap an inspect the rotor for any signs of impending burn-through. If it looks OK reinstall it with a dab of silicone sealer to help insulate it. If in doubt, replace it. Some guys trim the rotor a bit as well. There will be archived info on this procedure, as well as Marelli problems and cures in general.

If history is unknown, replace plugs and plug wires. Gap plugs to .025"

If you're ever driving the car and feel a loss of power, stop ! It could mean a Marelli failure where one entire bank of cylinders stops firing. This leads to overheated cat converters and....fire !


Fuel hoses:
Unless proven to have been done recently, replace all fuel hoses in the engine bay. The hoses to the injectors as well as the supply and return hoses. Lots of good archived info. This is a safety/fire concern

Cooling system:
Although you reported a steady temp gauge on your trip, which is a good thing, this alone cannot be taken as proof positive that the cooling system is 100%. Lack of coolant flow to all areas of the engine can create a disaster even if the the temp gauge doesn't suggest a problem.

There are varying approaches to V12 cooling systems. Unless records show otherwise I would consider the system overdue for service and plan on a full overhaul in the not too distant future. "Do it all, do it right, do it once" is my motto. The cooling system must be 100% on these cars and picking away at the items alá carte just prolongs the misery, IMO. If and when you delve in we can provide more details. And, if you like reading, there is tons of archived info

Cheers
DD

 

Grease the rear axle, in addition to Doug's list (10 grease nipples). Also drain and refill the differential with LSD castrol diff oil.