3.8 vs 4.2 oil pump?

I know that the one of the pipes on the 3.8 pump is smaller than the same pipe on the 4.2. I think maybe it’s the pickup tube? Anyhow I measured both of the ones on mine (a 3.8 engine) which is currently out. The pickup tube OD is 7/8" and the output pipe is 3/4. There is no adapter sleeve on either one.

So do I have an actual 3.8 pump, or is it a 4.2 pump and instead of using an adapter sleeve the whole inlet pipe was changed out? I should be able to remember this, I mean it was only installed 19 years ago…age related?

The lincreased bore pickup pipes were introduced across the range circa 64 /65
. If memory serves some ZB prefix 3.8 MK10s were fitted so. If your EType is61/2 or early 63 3 then pipe/pump have been chaged, iflate 63 orinto `64 then ?? If your block has a casting number C22250 ( top right side) then the 7/8"
pipe might be standard. A late 3.8 E parts book will inform, look for a changed part number
that tallys with the 4.2 item.
Peter B

Pumps with the smaller 3.8 ID are no longer available. So if you’re rebuilding a 3.8 you need to either modify your old pipe or just buy the bigger diameter pipe. It’s not the same as the pipe for the 4.2; I think the flange to the block is different (could be wrong here). The new pipes are cheap and it’s easier than modifying the old one if you can’t braze, so someone’s probably replaced that pipe on your engine in a past rebuild.

1 Like

It sounds that way. So then the 4.2 pickup tube is 7/8 just like mine?

I think so. I’m in the OT at the moment and can’t measure it but I have a 4.2 one at home so I’ll look when I get home.

As I am currently watching 3 surgeons being supervised by 2 ortho reps doing an ankle replacement, I may, to quote Lawrence Oates, be some time…

…on YOU??

Jeez, if it’s on you, I’d hope you’re not seeing it. I insist on the good drugs when I’m getting cut :scream:

1 Like

No I hold the patient down while they do it. Anaesthetist (Anesthesiologist in the US of A).

Ok measured the new 4.2 pipe I have and an old one out of a 420 engine. Both 3/4". Maybe the older 3.8 ones were smaller than that…

Yeah it does look like the mating flange is different. My 3.8 one just has two holes. But I think it’s the input pipe on early 3.8s that is smaller? The input is the port on the pump that I commonly see stepped down I think. My input pipe is 7/8". My outlet is 3/4" like yours.

Hope the patient is recovering!

1 Like

He has to or I don’t get paid and no more car parts for me!


Yes the delivery pipe on all 4.2 engines
Is three bolt, but we are talking pickup
pipe. I f anyone needs the increased
bore pickup pipe when using a EType sump, cut and shut the late MK2 / XJ
Peter B.

Have a 4.2 pump in ours. You don’t need to be an aircraft certified brazing expert to put the sleeve on the pickup pipe - the thing can’t really go anywhere. I don’t advocate using model airplane glue, but if the flange doesn’t mate, fixing the old pipe to go into the larger intake 4.2 is a very easy modification. Our 3.8 has the 4.2 intake, radiator, water pump and oil pump. Head drilled out for the other style water flow, so I claim best of all worlds - but hardly original.

1 Like

aHA!!! You’re a gas passer…:grimacing: