1993 Jaguar XJS 4.0, coupe (LHD)
I've been able to trace a coolant leak that appears to be originating at the "multi-hose" coolant distribution manifold located rear to and on the outlet of the water pump. I removed the air cleaner canister, swung the emission pump downward and out of the way, however, the exact leak location is hard to identify as this coolant connecting manifold is hidden under the inlet manifold. worse still, the connecting hoses all have very hard to get at "worm-drive' clamps. My friend "the mechanic" made the comment that this leak emanates from the water pump and is an indication of a leaking and worn water pump! This observation, however, seems to be in conflict with the apparent location of the leak itself. Can any Member provide me with some insight before I resort to removing the whole fuel manifold from the side of the engine just to get at the coolant leak location or could it be that I just need to replace the after pump?

 

just to say... lots of folks have eliminated that belt driven air pump. eliminated it all together and this does wonders for visibility. from what i read it sounds like this might be in and around the area you are looking at... on the RH side of the engine. if it were me, before taking off intake, I would try to get that thing out of the way.

LOTS of DRIP SOURCES...

on the RH side there is a short section of hose #4 (is yours a a v12?) that can leak,,, there is a cross over pipe that connects to the "#4's" on both sides, actually. Ive always wondered how the HECK they dont leak all the doggone time....

Then, there are dual thermostat housings. one on either side.. all can leak. then, more than that, there are 2 water rails (metal) that run UNDER the intakes on both sides. Again, if it were me,,, with a flash light and car running I woud start inspecting those areas after googling the hell out of the v12 coolant system so you can have a really good idea of where you might expect to find water under the hood. and stuff. It could be on the the RH side, a heater hose is leaking way in the back of the engine near the fire wall and slooooowly traveling the length of the water rail system and showing up inthe FRONT of the motor. Ya never can tell with these machines - tricky that way.

 

Thanks, JayJagJay.
1. To clarify, the car is a 6 cylinder 4.0 liter circa 1993 XJS coupe, LHD. The side of the leak is the LH under the file inlet manifold, not RH as you mention
2. the diagrams you attached appear to be from a V!2 configuration (so looks very different from the 6 cylinder layout)
3 I agree it is time to remove the emission pump but what to do with the two connecting hoses and electrics (maybe another thread?)
4. for the time being, just releasing the pump from its mounting bracket provided a good enough view of the coolant manifold connection I mentioned
5. I'm just trying to figure out if this leak can be traced to the water pump operation of a "blown" hose.
Really appreciate your reply..hope this clarification helps
chris

 

The best way to find any coolant leak is to pressurise the system to 1 bar after a cold soak, preferably overnight. If the pressure on the gauge begins to drop off after a few minutes see if the leak can be located whilst under pressure before starting any disassembly of the engine.

 

Shoot... You did,,, you offered that info, right off...
Im sorry, I cant help with the 4.0 6cyl. Haha, Ive just gotten brave enough to offer suggestions for the v12.
Well good luck and,,, what NB said. Clearly there are folks here with a lot more experience than yours truly,
You'll git it!

 

Thank you Sir..good advice and I'll set-up a pressure test before going any further.
chris

 

HI Chris, dont cha just love Jaguars, but they are like many cars , need maintenance from time to time!
drop by i maybe of help?
ron

 

The leak is almost certainly the short (6 inches or so), slightly S shaped hose that comes straight rearwards off the water pump under the inlet manifold. It is invisible and gets lots of heat. If you have never changed it, then I suggest you start with that.
Number 3 in this diagram
https://parts.jaguarlandroverclassic.../brand/jaguar/

 

dont forget that there are a pair of small coolant hoses that actually attach to the bottom of the Throttle body on the intake manifold and run coolant through the manifold ( dont ask me why ) ,
so as indicated above it would well be the ' ******* hose ' and also the small gaskets holding the cast pipe to the cylinder block in two places off that 6" hose ,but there are other pipes with coolant under there, and they are only small pipes , the large pipe can be easily seen here i my head replacement project...

BB

 

Thanks "Brake buster" for your photo. These "naked engine" photos are precious to uninitiated XJS owners like me who rarely and hopefully never glimpse the "unmentionable" bits. From the location of the leak (i.e. directly behind and underneath the inlet manifold), I'm inclined to think that the culprit is either the hose you describe or one of the others mentioned by Greg above. Either way, on Monday, I'm rolling up my sleeves and begin removing enough of bits so as to visualize the leak under pressure as well as replacing the water pump.
In an earlier post, I asked if any Forum Members (American I guess) had actually removed the emission pump and if so, what is needed to isolate the two connecting hoses which no longer has a home?
I'm so pleased that you and other Forum Members have taken the time to reply to my posts as these are much appreciated.

 

Thanks, Greg for your reply. As I mentioned in my reply to "Brake buster", I'm about to begin the task of removing bits so as to locate the actual source of the leak as well as replacing the water pump itself (thanks also to vettecat, JX350 and Mark in Maine for their warnings about removing the pump bolts). Interestingly, the hose part number EAC3454 you identified can, under the brand URO, be obtained from multiple sources for $US10 (versus the £25 required by the UK supplier!). There does however seem to be some confusion as this part was alternatively shown as fitting an XJS as well as XJ6 models. anyway, the price difference is enough for me to go ahead and order the URO replacement.
My main concern is being able to access those and worm drive clips without removing the whole inlet manifold, air handling gear etc. that resides above these hoses!

 

You can get to them, not easy but I have done it. I would be leary about the cheaper hose, unless you are certain it is just as good as OEM. The hose gets a great deal of heat and you cannot see it and if it is deteriorating. This is one area where OEM might be worth the money.
What makes you think the water pump needs changing?

 

i agree with Greg , Genuine jaguar parts in this area all the way,, false economy to be honest to fit ' unknown ' parts , even from the usual jaguar parts suppliers, these are usually fitted to cars that are being ' sold on ' and they dont worry about the longevity of the part fitted,

these pipes can be seen from under the car , securely and safely held up goes without saying, identifying the leak would be quicker this way , look for ' tell tale ' signs of dried coolant on the engine or pipes to guide you in the right direction, sometimes all thats needed is a nip up of the hose clamp, unless its a mating seal issue

good luck

BB

 

Thanks, Brake buster (again)..Yes, my first move is to get the XJS up on the lift and try to get a definite view of the leak location while pressurizing the coolant system. when viewed from above, father running the engine temp up, definitely seems to be coming from one of those hoses mentioned above (nothing "dried coolant" about it....quite a visible flood so to speak!). If there is a God, then let it be "a nip up of the hose clamp". however, based on my biased experience of other British cars (Rileys, MGs, Healeys, etc.), most unlikely!

 

Greg, to answer your question, " What makes you think the water pump needs changing?". all I can offer in my defense is that m,y "resident mechanic" is of the opinion that this is "always the cause as there is a weep hole, etc.". This, despite the fact that the leak appears to be well behind the pump housing as described in the diagram you posted. The next step is to pressurize the system while up on the hoist and attempt to get a visual on the leak location before moving ahead. That's happening on Monday. Thanks again for your postings...always welcome
chris

 

The ******* hose can be changed on the XJ40 without dismantling anything else. I would expect it to be possible on XJS as well.
It no fun to do though, and a bursted hose lets all water out very fast, so you will want a reliable hose. I would not go for anything less than original, and I keep a spare in my boot together with a CPS...

 

Hey..thanks Leo....not sure if carrying a boot-load of spare hoses would be much help when confronted with a serious road-side coolant leak. That's a lot of $$$$ tied-up as in
https://xks.com/i-6918705-jaguar-xj-...t-29-8618.html

 

I’m on my third B-hose (it’s by the way amusing that the forum automatically replaces swearing with asterisks). All other hoses are original, so if you should bring one hose, this is the one.
Any workshop can replace it, so having it in the boot makes the difference between fixing it in 2-3 hours or 2-3 days if you’re far from home....

 

Forget the water pump, change the hoses. Then see. I would replace ALL the hoses, as this sort of preventative maintenance is really worth it.

 

agreed




here is a picture from the underside, in it you can see the red TB sensor, to the right are two small pipes in the black induction manifold , on on each side of the inlet manifold coolant circuit ,you can see the jubilee clips on them, these two small pipes can be damaged or the clip loose, , slightly to the right of these
connections is the B'hose main cast pipe which fixed to the block , so this should give you some orientation under the car







BB