So i noticed that my 93 xjs 4.0 was leaving oil puddles in the work parking lot and in looking i saw lots of oil from the oil cooler block that’s bolted behind the oil filter. After some debate, i decided just to do as others have done and am removing the block, and bolting the oil filter plate straight to the engine. Im in the process of putting everything back together now. We’ll see how it goes. It gave me a chance to do some other cleaning up in there that ive wanted to do too!

 

A long time ago, I clarified the oring sizes for this project. I used viton orings.

I’m hoping your planning on replacing them.

 

My oil cooler lines are leaking and my Indy says they have to custom make them. I did not know that it can be deleted. How does this affect the engine in hot climates? I wanna do this. Howd you find out about this?

 

Hi Brewtech,

On cars that never had an oil cooler fitted (many XJS including mine and XJ40s) there is a short bypass u-bend box that just bolts on where the oil cooler hoses exit the oil filter assembly. Prone to leakage due to the o rings that seal the arrangement becoming brittle over time. I had to replace my o rings and wrote up for the local Jag club. Copy of the article attached and hope it helps understand the arrangement. Maybe you could track down the fitment through a breaker?

I understand that it was only 6 cylinder cars that were exported to hot climates that were fitted with a cooler which I guess includes much of the US. I'll leave it to others to comment on the need for an oil cooler in your part of the world.

Cheers,
LeeP

 

I'm not convinced that any six cylinder XJS needed an oil cooler. 4 litre XJSs had oil coolers fitted in all countries, but the x300 XJ6 saloon with the same engine didn't have them fitted at all.

So why were they fitted to XJSs? I don't know? Did Jaguar think XJSs would be driven harder than the saloons? Is the airflow through the water radiator more marginal on the XJS? Who knows. All I would say is that IMO, 4 litre XJSs don't overheat if maintained properly. Any overheating problems that we hear about are where owners have a problem with the cooling fins on their radiator or internal clogging of the rad. And the fin damage on the lower third is often caused by oil leaks from the oil cooler anyway, as oil drips get thrown onto the fins, which then collects road dirt and debris and gradually deteriorate. So I reckon you're better off without it.

I have a couple of the bypass kits and next time my oil cooler or pipe lets go, I'll remove it and fit the bypass unit.

Paul

 

I live in Washington DC. Summers get pretty hot.

I deleted the oil cooler years ago.

I daily drive my 96 XJS with the AJ16 engine, in all seasons. No issues since deleting the oil cooler.

 

No sir im removing the block between the oil filter plate and the engine completely. No o-rings to worry about forever.

 

Basically I just did a web search on the oil cooler hoses and o-ring leaks and after much reading about deleting everything, and seeing that the "fix for leaky o-rings" issued by Jaguar was to delete the hoses and the cooler, i decided id just do it..

 

So i did it. Of course while i was there i cleaned my throttle body, leaving the tps in place, figuring that may be the best was. Of course then i decided “shucks! Theres no gaskets whatsoever between the throttle body and the manifold or between the elbow connector and the throttle body! Maybe that’s why I have had a shudder at throttle let off!” So i made gaskets and installed them. Of course now that i have it all back together, it starts immediately, then shuts off immediately. Argh! Looks like ill probably have to take some of it back apart, after i have someone else try to start it so i can see if i see anything i missed.

 

There is no gasket between the manifold and the throttle body. I can't imagine it would hurt, but be careful not to block anything with your homemade gasket. I think I unknowingly did when I tried the same thing. I would recommend just applying some Permatex Permashield #85420 if you want to apply something. Its fuel resistant and stays pliable.

I'm not sure what you're talking about regarding the elbow connector and throttle body. Should be a rubber boot with a giant hose clamp?

 

Didn't know you could do that. Interested to hear how it goes.

Cheers,
LeeP

 

If you delete the sandwich plate, won't you lose the bypass valve which presumably enables the oil to keep circulating in the event of a blocked or failed oil filter?

It seems safer to keep the sandwich plate and just fit the bypass kit.

Paul

 

So yeah, after my son got home we checked and i have to take the throttle body off again. Pretty good vacuum leak at the throttle body. Ill have to take it apart again. As for the bypass valve, im not positive, but I read that the oil filter itself has a built-in valve just in case too. I guess we'll see

 

Yeah i meant at the boot. After the plastic intake elbow

 

You sure that boot is on right? Sometimes it folds in on itself under the TB....

 

100% correct.

 

Yes sir I triple checked both ends of the boot. And yes it is a total pain to get it on right. Im surprised they dont rip more frequently than I see people saying

 

Soooooooo i found my air leak!
I must’ve hit it with something during the work i was doing! ARGH! On another note, i also found out that my oil pressure sensor is leaking oil too! YAY! SMH!

 

I would have been more surprised to hear the your oil pressure sensor WASN'T leaking. Seems I have to fiddle with mine every two years, or less!

As far as the intake manifold, how the hell does that happen? I doubt you did anything to break it, it was probably hanging on by a thread on some previous impact.

 

So i found and ordered a complete intake manifold on ebay for $95 shipped from California! I figured id then have some spare parts laying around lol. Also i pulled my oil pressure switch and its leaking around the plastic, so i bought a new one. Hope to have her up and running by the middle of the week!