Will a 3.8 oil filter head fit a 4.2 block?

I’m putting a 4.2 (MkX) into a Mk2. I’m almost finished with the engine build. I made a few mistakes along the way (I’m new to Jaguars!), like not realizing that the original sump would not fit. No problem, I had the 3.4/3.8 sump, but few other 3.8 parts.
The problem I have now is that the filter head from the 4.2 interferes with the oil pick-up tube whether I use the 4.2 or 3.8 tube. This also means that the oil filter (conversion kit) also hits the sump.
I know a lot of 4.2s have been fitted to Mk2s, so what is the solution?
I suppose the logical solution is to find a 3.8 filter head and exchange the conversion kit. Seems like the obvious solution, but will the 3.8 head will work on a 4.2?? Which one? There seem to be 2-3 types (2 in the Mk2 shop manual and I think another for the XKE).
A remote filter kit might work
Other options?

I bet filter base should mate the block via distance piece clearing it from sump. It’s a 3-4mm thick plate.

I can’t answer your question except to say that I fitted a 420 engine into my Mk2 recently and used the oil filter housing from the 420 which fitted fine with the Mk2 sump.

There are a lot of oil filters for the Mk2 (see here) and yours doesn’t look familiar to me although I am no expert on them.

I think you are incorrectly referring to the oil pressure relief pipe it’s not the oil pick up. As such you can modify it using flexible pipe (hose) provided you use oil resistant hose. However a standard mk2 filter is the best option which should be readily available secondhand on eBay ?

All the XK Engine blocks have the same oil way’s , some have 4 mounting points some have 5 for the oil filter housing, you just have to use the right Gasket !



Ive never understood why they ever made any other configuration than this. Solves a lot of fitting issues.

Could Jaguar possibly have made it more complex and confusing?

Where can I find this piece? I don’t think I’ve seen it in the aftermarket.

Sorry, Phil, yes oil relief pipe. I have 2 original filters; one from a Mk2 and one from a MkX. Neither one fit. The MkX head puts the filter too far back and it hits the sump. The part of the sump that kicks out is further back on the MkX. I also think that the original filter style is inadequate for modern use.

Thanks, Ian. So, I just need to find the right head for clearance… an Mk2? The Mk2 shop manual shows the correct gasket for the 2 types of heads. Thanks for the illustration!

John, honestly, this is almost as complicated as Ford 302/5.0L water pumps and sumps.

What is modern use :thinking: I drive my car like I stole it for a good few miles , every time I take it out !
My XJ6 Engine with 240 filter housing ,
Was very pleased to find out , the original XJ6 feed to the cam’s bolted straight into the top of the filter housing !


Don’t know where to find the spacer but it should be quite easy to make. Here’s my Mk1 '58 modified kit.The spacer is 3,3mm thick steel pate with holes.

Thanks, Lesio. I may need to do that, but that won’t be enough clearance. If you look at the photo Ian posted you can see that the 3.8 head kicks the filter out away from the block allowing it to clear the sump, whereas the 4.2 head places the filter parallel to the block. I think that angle is the trick. If it’s not quite far enough I may need to make a spacer.