What is this part called?


I have a leaking part on my engine, but im not sure what it is for.

Its a leaking mess and i have to adress it now.

Maybe with the name i can find a tutorial or info on how to fiy this part

Any help is appreciated

(Its this entire cylindrical part with the long number stamped.on )

That is your power steering pump. They are a GM style unit but they may have a specific pressure relief for the Jag application.

It’s usually the hose that leaks

okay thanks, is there a way to remove the power steering fluid so i can try working on it without making a mess?

Turkey baster is what I used to empty tank; after doing that undo hose end from tank then point undone end into a container under the car and let the hose drain.

Thanks, i got a little handpump for that :)=

I also noticed a leak on the other side of the engine of my 1990 xj40
Its below the oil filter housing. I’ve read that some O rings there tend to leak and that the partnumber is called CAC-5118.

Do some of you know the specifics of that O ring? Does it really have to be this OEM part or can i grab a fitting O ring from the Hardware store? Its really hard to get such specific parts into Switzerland without insane shipping fees.

Im also kinda scared that the sump pan is leaking. I’ve heard its 100% an engine out problem right? Or is there a way to do it without removing the engine?

There’s also a good chance the sump pan is NOT leaking, any oil leaks from higher up the engine tend to collect around the lip of the sump giving the impression that it’s leaking. I would fix all the other leaks you can find and then clean the area around the sump pan joint before driving the car for a while and checking it again. I would replace the cam cover rubber seal along with the ‘D’ seals, the O rings and gasket on the top chain tensioner located near to the distributor, and the O rings on the oil cooler by-pass ( if fitted) then use a mirror on a stick to check if the oil pressure sender located on the engine block under the inlet manifold is weeping and change that too if it is. I was CONVINCED my sump was leaking but once I’d attended to all the other minor leaks from above, that sump joint has remained clean and dry for the past few years. I hope yours turns out to be oil tight too, good luck.


Hi Casso

It would be good news if the sump isnt leaking…

I’ll try to adress the main leaks and then hope the sump inst leaking. Its a bit suspicious that the previous owner smeared some rtv on the outside of the sump.

But when i was under the car while it w as running, i could see the oil flow towards the sump seal from ABOVE… So maybe there is indeed a change the sump isnt the leak

1 Like

I agree it looks suspicious but there is a good chance he too was wrongly convinced that the sump was leaking, any leaks from higher up the engine that collect around the sump joint can easily give that impression. Good Luck.

1 Like

thanks Casso,

I will let the leaks be checked out by a hobby mechanic with lift later this week.
This way its cheaper than the swiss mechanics with a registered shop, they charge up to 120$/hour just for labor… ( an engine out job would be financial horror)


by the way.

I heard some xj40 have a oil cooler bypass below the oil filter

Why is that? can i do that on my xj40 too? If so what are the downsides?

my jag already has the air suspension and AC components removed cause they are so costly to repair. Id’ keep going that route to remove stuff if its not necessary

1 Like

Can’t say I have heard of that, if your car has an oil cooler the connections can be removed by taking out the oil filter head and removing the block with the cooler connections then a light smear of RTV and shorter bolts to replace the filter housing.

Yes my 94 has the bypass unit. Still, what @Robin_O_Connor says above is a better solution for cars like yours. No need for cooler.

Okay then i might order a oil cooler bypass.

But why is there a oil cooler id its not needed?

When using o-rings on engine oil applications, make sure the rubber is Viton, Not Nitrile or BN (Butyl Nitrile). BN will start to harden and get brittle at 250F where as Viton will handle 400F. Engine oil operates in the 250-300 degrees so do it once with nitrile o-rings and be done.

Thank you Dick Maury for your input! :slight_smile:

The plan is now to buy a proper oil cooler bypass and fix the leaking oil cooler housing. the majority of the leaks are coming from there.

Now, i really want to buy the correct part, so im asking you all for some help again:

XJS Oil Cooler Bypass Kit XJSBPK - Berkshire Jag Components

Will this part fit my 1990 daimler xj40 ?


Marmo, according to the Jaguar parts site:


the kit you cited should work with your car. The kit contains parts 4, 6 and 7 shown on the aforementioned parts site:

Now the question remains: what about the means to attach the bypass pipe - the stud (#3) and nut (#5)? Your car does not have those parts unless the bypass has previously been installed, which it has not been - that’s the point of this exercise, right? Robin’s suggestion in post #11 of this thread is the simplest, least expensive solution.

1 Like

XJSBPK looks like the correct part setup.

Ohh i think i missunderstood him.

So i could simply remove all parts except 8 9 and the oil filter 10?

seal it off with rtv and use shorter bolts? would this really be seal proof just with rtv?

If so then i think this would be the easiest fix :slight_smile: (sorry im really new to this stuff)

Yes, that is what I understand from Robin’s post.