Oil leak jag xj40

High Pegleg here.
1988 xj40
Have an oil leak on the oil cooler/ filter housing ? o rings cracked.
Any suggestions to fix, and has anyone got any pictures of oil block housing.
Thank you Pegleg.

If the leak is from the ‘O’ rings for the oil cooler feed and return pipes, unless you operate in high ambient temperatures, the oil cooler is surplus to requirements and you can remove the adaptor and bolt the oil filter housing directly on to the block. Many searchable posts in the XJ40 archives on this subject - here are a couple of examples :-

The only picture I can find of the oil filter attachment is for the later models with the oil cooler bypass feature item 4 (when they deleted the cooler) but the arrangement is the same on the earlier models with an oil cooler. You can simply remove item 1 and bolt item 8 directly to the block using shorter bolts.


I would recommend just going ahead and changing the O-rings instead of eliminating the cooler. If my memory serves me, there is only one nut that holds the inlet/outlet lines to the housing. Just remove the nut, pull the lines down so you can see the o-rings, R&R them, and hook the lines back up. It helps to have a dental pick or something to get the o-rings out of their groove. I had to do this years ago when I first got my car, and it wasn’t too bad of a job.

There is another upside to eliminating the cooler, after an oil change the oil stays clean due to not being contaminated by the 1-1 1/2 litre which cannot be drained from the cooler. If you do remove the cooler lock make sure you do the bolts up TIGHT!

Mr Pegleg …

Just to chime in, I solved my leaking oil cooler line problems on my '89 years ago by getting rid of it !

Nothing makes me happier than pulling unnecessary hardware out of my car. And when eliminating the oil cooler system for a simple bypass made me happy … eliminating the hydro-mechanical brake system for a vacuum system made me absolutely delirious … (but I digress).

Here in Dallas Texas it was 110 degrees and I had NO overheating problems whatsoever in stop and go traffic even with my A/C at full blast. So unless you live on Mercury (or somewhere in the Mideast) You really don’t need that oil cooler and maybe that’s why Jaguar eliminated it in later models.

I removed the oil cooler with all the associated parts yesterday. I followed Bryan’s instructions, and I am very pleased with the results. Thank you, Bryan!