Oil leak RH engine side

Hello everybody,

after several weeks of rest I took the Jag out for an extended ride (50 mls motorway return trip in one day). The good thing: despite less than friendly conditions everything worked as it is supposed to - car started after several weeks of sitting at first turn, all electrical systems including rear heated window, wipers all speeds and return worked in foggy and wet weather - and the car didn’t miss a beat on the early morning ride to the airport and back at night.

Yet, the cat left a puddle of oil at one point at the rh engine side and short behind the front wheel. What is more - when backing out of the garage a track of oil was spilled in a straight line over like 7 feet, indicating that a bigger quantity of oil had accumulated at some point and poured down when the car was set into motion - and it was the second time it did so after a longer period of sitting.

The engine side looks dry from above. The problem is I’d have to leave the car on a lift for several weeks to simulate the situation and be able to check. Whenever I have used the car and taken it to a lift the engine looks, well, Jaguar-like, meaning a bit oily, but nothing indicating a serious leak. My suspicion would be the oil filter (old school paper filter in cartridge).

Are there any other known suspects around this area - external oil lines maybe where gaskets may have hardened out?

Any idea welcome! Enjoy the weekend ahead


75 XJ6L 4.2 auto (UK spec)

Hello Jochen,
Probably wrong engine and gearbox, but I had similar oil leak problems from my GM400 gearbox and V12 engine on a series 3.
The membrane on the vacuum modulator of the gearbox gave up and the gearbox oil went up the hose to the inlet manifold of the air intake of the engine. The oil then leaked out of the air filter box (right side of engine) and down to the floor.

I‘m going to assume that it is neither transmission- nor power steering fluid, both of which would be red (the transmission tends to drip after about three weeks). If it is motor oil, it should be from a non-pressurized part of the engine as it leaks out over time, not because of pressure. First idea is the pressure relief from the filter housing into the oil pan. You could clean it all with brake cleaner and then inspect the hose and gasket there.
Glad the rest works. Do you happen to be in constance on Tuesday or Wednesday?
Have a nice weekend,


Thanks Neil and David!

Strange things can happen, Neil, but in this case - David is right - the oil was quite clearly engine oil, not gearbox oil.

I’ll have to have a closer look at the oil filter connections, I guess - have to find out where that oil pool is forming. Thanks again for the helpful ideas!

Yes David, I’ll be around on Tuesday and Wednesday. PM me to arrange for a meeting.

Enjoy the weekend


75 XJ6L 4.2 auto (UK spec)

It could be from the distributer seal?


Or the dipstick, but neither see that much oil…
Only the return hose sees high pressure after a cold start, and a lot of oil will be bled back to the sump, enough to produce a pint of oil, or more, on cold starts.
Another possibility one might think of is the oil pooling on the front axle, coming from one of the usual leaks and accumulating there just as my size 10 sockets tend to.


I had a similar issue with a leaking oil pressure sender unit on a XK engine. Even with the engine switched off some residue drained from the sender can for a while and dripped from parts already coated in oil.
Of course with the engine off the leak will subside and when the engine is run it can take a while to start leaking.

As I recall, vaguely, there are a lot of seals and stuff around there. some already mentioned. My vote would be for the oil pressure senders…


Thanks Gentlemen!

Yes, I replaced the oil sender a couple of years ago - will check that. The distributor seal was not on my agenda, neither the oil dipstick. The upside of the front suspension carrier could serve as an interim pool - I’d have to find out though from where it is fed.

A chance to do so tomorrow:-)

Thank you all again


75 XJ6L 4.2 auto

Hi david!

You mentioned front axle, it also could come from the power steering,


Walter, that would have a tendency to be red…
Jochen is sure it’s engine oil. Wouldn’t mind having a look tomorrow

The pressure sender, wouldn’t that leak the most when hot?


Correct, Walter,

the P/S is not leak free either, but it leaks less, in a different colour and to a different spot;-).

Thanks again


Did you try torquing down the bolt on the oil filer canister? I’ve had that happen where it seems tight but oil still gets past the o-ring. Will leave quite a puddle after a dive. There are 2 oil pressure sensors on the right side. The pressure sender is mounted on the top of the filter housing. There is a pressure switch that turns on the oil light on the instrument panel. That screws directly into the block to the right of the filter housing. All of these will leak when under pressure as the engine runs. The oil filter canister can drain out after the engine is shut down and leave a sizable puddle. That usually leaks onto the power steering rack. A valve cover gasket can leak and run down the side of the block and be hard to see sometimes. Have you noticed if you are “using” oil? Did you have to add any?
When the car sits for any length of time, all of the oil returns to the sump except for a small amount in the heads under the valve covers but below the gasket level, and in the filter canister.
So my best guess is the filter canister seal. Also take a look at the return hose going back to the sump.

Thanks Lawrence,

two days ago I put the car on a lift and - together with David Jauch who helped me wonderfully! - we checked possible sources of the leak: the oil sender is bone dry.

There is a drip down from the steering rack rubber gaiter as you describe it, and the lower part of the oil filter canister is wet. So the path of oil you describe is certainly one suspect. Unfortunately, there is no simple cause of this leak as the main canister bolt is tight - I checked this - and the canister used to be oil tight when I changed the oil and filter last time. What is more, this leak maybe clearly visible, but it produces nothing like the puddle that is created within a few seconds upon cold start.

In fact, when I cold started the car on Wednesday after roughly one week of sitting, I backed up the car, stopping there for about 30 seconds before continuing to leave the parking spot. Within that short period the car lost a big puddle of engine oil around the location of the oil filter.

So I’m fairly sure that this is not just oil that has pooled some place (the main front subframe carrier is dry as well) and then found its way down upon moving the car, nor is it oil dripping through seals after many hours and days of sitting, but it must have to do with high oil pressure upon cold starts.

David suspected the relief valve or the cam feed pipe. The latter seems to be excused as the upper part of the oil filter was dry, but it could be just about anything around the base of the oil filter canister.

Next time I cold start the car I’ll bring someone to check visually where the oil is pressed out.

Thanks again and enjoy the week end


75 XJ6L 4.2 auto (UK spec)

Just for the record, Jochen; did you check/change the seals when you changed the filter - and made sure you removed old seals if changed?

To tighten the bolt beyond specs is not really a proper solution…

xj6 85 Sov Europe (UK/NZ)

We checked for tightness. No overtightening.
The hose from the relief valve to the sump is hardened, but not full of oil (although to me it is still the one part that makes sense!)
The filter housing is wet and the steering rack (RHD). It is engine oil. The cam feed line makes a lot of sense: if it were to spray oil at the junction to the oil filter block the distribution makes sense. Just maybe, the gasket to the block could be responsible but it really wasn’t clear…

Frank beat me to it. From time to time folks like us do not remove the old filter seal and merely add another. Result, leak almost guaranteed.

And, no one has mentioned a cam cover gasket. Oil leaks have migratory instincts. Oh, other liquids as well!!!


Cam cover gasket, not on that side, and no way it’s that bad and quick (and only at startup). The oil spill that occurs, and only at cold starts, is really bad.

I am with Frank on this. I suspect that your problem is due to a failed seal between the oil filter head on the engine and the oil filter canister.

There is a small seal in a groove on the filter head that is supposed to be changed with each oil filter change (but no one really does that). That seal can get cracked or twisted and create an imperfect seal. Sometimes a second seal is added in error when the first seal is not removed. If the seal fails no amount of tightening will fix it.

I know about this personally since my 1969 E-Type had the original oil filter canister when I got it. But, within the first few years I had trouble getting the canister to seal properly against the filter head a few times with resultant oil leaks. I eventually installed an aftermarket spin on oil filter adapter to prevent future leaks.

The original design can work correctly with a good seal properly installed and the bolt properly tightened, but stuff happens. :wink:

The spin on oil filter adapter has always sealed properly and since I installed it (about 15 years ago) it has never leaked.


Thank you all,

the Lucas oil filter cartridge comes with a rubber seal and, yes, it was replaced with the last oil change. It’s a bit fiddly and I think the first time I did that I even found a second rubber seal propped into the groove …

As David wrote, the sort of wet lower part of the filter may cause an occasional drip, but not that kind of violent leak as happens right upon start up. I can’t imagine that the oil filter housing sees the same kind of pressure as the oil circuit.

Today was the day for preparing the garden for winter service - will check the car tomorrow!

Thanks again


75 XJ6L 4.2 auto (UK spec)