Will 3.8 sump fit on 4.2 Mk10 engine?

I’m well along on my engine rebuild for the Mk10 and also far long on the transmission conversion to GM700r4. A complication arises about the sump. The Mk10 external oil return fouls the GM starter. I had though I could modify the return tube, but as I fit things up, there is not enough clearance. Possible solutions include modifying the Mk10 sump or using a different one. I have a parts engine from a 3.8S that has the oil return angling into the front of the right side sump “ear” rather than at the top, and I think it will work as far as starter clearance. John’s Cars kit does work for these with a change in the oil filter housing from angled to vertical style.

I think the oil sumps are interchangable between 3.8 and 4.2 blocks. Can anyone verify this to be true? I think the pickup tubes are probably the same. If nobody knows for certain, I’ll have to pull that sump, and I hate to break it down just to find out.

Ron, all XK sumps are interchangeable except the early ones without a rear main seal

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That’s what I thought. Thanks.

Oil sumps are interchangeable: oil pickup tubes are not.

My 420 had a xj6 oil filter adapter and return pipe that had been modified. The filter was tiny due to space. I have a xj sump I have no use for if it would help you. I’ll take a look at it tomorrow.

Many thanks. I dug through my stash and found a 420G sump I’d forgotten about. They moved the return fitting forward for some reason, and it looks like it will work just fine. For some reason, it’s missing the baffles, but I think the Mk10 ones are the same - will find out today. I also looked at the spare xj6 engines I have and I believe their sump would also work fine, so your suggestion is a good one.

So, I started to clean up that 420G pan and found that the ugly grease spot was actually an ugly bondo spot because of a crack - unusable without extensive welding. I pulled the pan off a series 3 xj6 motor and cleaned it up, installed it along with its slightly longer pickup tube, and was congratulating myself, until I noticed that the stock Mk10 filter canister barely doesn’t clear. I’m left with the choice of making a 3/8" spacer to move the filter body out or putting in a later XJ filter base. The XJ would be good, because the oil return line wouldn’t need the corkscrew return that the stock one would, but it’s bad because the filter canister is too long to clear the flange on the inner fender well of the car. The one on the spare motor does have an oil cooler if I could figure out a place to put it, but I have another without.

So, question: what is the short filter you referred to? I need something that gives me total depth of not more than about 5 1/2" from block to outer edge of the filter can, the stock XJ unit with Fram about 6.5". Another option is to check into the spin-on kit that John’s cars sells.

The engine bay in my 420 is very narrow. It had the XJ adapter like you have. The oil cooler ports had aluminum plugs in them, I believe from John’s Cars. The filter was less than 3 inches tall and not much larger in diameter. I felt it was too small. I later installed a different oil filter housing that positioned the filter downward and could handle a larger filter. I’ll attach a picture or two for reference. I still have that housing. I put the spin on adapter on it. My current arrangement angles back like original with the same spin on adapter which clears the steering and now I have a larger filter yet.

If the vertical filter housing would help I’ll make a good deal.

My current oil filter housing wouldn’t clear the starter with the John’s Cars 700r4 conversion. Due to starter interference. The one pictured does clear.

Saying that adapter plate, makes me realize I’m pretty much stuck with the BW 66 in my hot rod.

Using the spin-on adapter is an interesting option that I hadn’t thought of. I can see why you would go back to the angled housing now that you have the manual o/d transmission. I do have the vertical housing already (thanks very much for the offer). I think the simplest solution for me might be just to make the spacer, but I’m going to make a trip to FLAPS and see what the longest filter that could be fitted with the XJ part might be. I might have a little more lateral room on the Mk10 than on your 420, and there is a flange that could be trimmed.

Regarding that XJ housing, I was under the impression that the ports to the cooler had to be open to allow circulation through the filter, but I could be wrong about that. I remember looking at it when I fitted one of them to my XK120. If it does work, I might be interested in buying your plugs.

Wix has a good site for filter comparison FYI.

That is really helpful. The correct Wix is a little shorter than the Fram that is on the parts engine, but probably still too long without body mods. I’m not sure what short Wix you were using, but none of the shorter ones on their chart with compatible thread and external dimensions have the same bypass characteristics as the original. I checked the Fram site, and they don’t have the same lookup capability. I’m going to buy the Wix, unless FLAPS has another suggestion, but I think I’ll probably have to do the spacer plate. Even so, that will allow a spin-on adapter later if I choose.

I know zero about the Mk10 engine bay, but this is what I did. The sump drain plug is the same thread as the non-metric GM power steering pumps that are popular in some oval track race series. I screwed the -6 AN power steering pump hose adapter into the sump drain and used a slightly different - 6 AN adapter in the bypass port on the side of this XJ6 (S2, I :thinking:) spin-on filter base. Yes, AN fittings and hose on the zero pressure bypass port are order-of-magnitude overkill.

Early mockup with different filter mount

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Yes, I have a similar arrangement on my 120 (this is a 140? I think the pan drain is on the other side on mine), but draining to the oil level opening - yours is more elegant. It won’t work on the Mk10, though, because the filter canister fouls the unibody.

120 chassis, but an early smooth E-type sump. The gee-wiz-enormous oil filter is a Porsche 911 Turbo application, which uses the same 1" nipple as the XJ6.

Yes, an amazing filter. Wish I could fit that.
I did sent an information request to Wix about a shorter filter and I’ll share that with you about the internal structure of their filter in case it’s pertinent.
"When I look up a 1987 Jaguar Xj6, it lists a 51231. This oil filter has and requires a plastic stand pipe inside of the filter. We do not offer a shorter version of this filter. "
I’m not sure what the stand pipe does or whether yours needs it.

Looks like I can’t use the XJ base without cutting the body, which I don’t want to do. So, I’ll make a spacer plate to stand the original Mk10 base off by 3/8". The other troubling problem was finding a 5/8" 90 degree oil-compatible hose to make a clean connection to the sump pipe. It seems that the only one in the world that could be found is in Australia.

Just ordered it for $48 with shipping. Silicon hoses are apparently not ok for oil, and getting a good rubber one is also difficult. Anyways, I think this will work just fine and will leave plenty of clearance for the GM starter.

I finally found the number of filter that was on my 420 when I bought it. It was wix 51335