I removed the water pump. No sign of leak, weeping, bad seals nor gaskets. No issues behind the pump or under supercharger either. The only signs of current coolant stains are at the bottom of the front engine cover and a slightly damp recovery tank hose at the engine end.
I see several items of concern.
1. The recovery tank has air bubbles when the engine is running. This implies in my mind, a system breach somewhere sucking air and purging at the recovery tank.
2. I am definitely losing coolant somewhere but can’t see the source.
My last exposure to a mystery coolant loss resulted in a bad head gasket but, I can’t believe a car with 44k miles could have this.
I’m in the process of removing the second splash guard so I can see the entire engine and transmission. I’ll also drain some oil to see if I can spot contamination (would be ez if it had a darn dipstick).
Should anyone have a clue where my leak can be, please post your suggestion, theories and constructive ideas. They are sincerely appreciated.

Sign of active coolant leak below the black front engine cover

Coolant damp recovery hose at the engine end.



Air bubbles in coolant tank. Normal??

 

Two thoughts :

Get a cooling system pressure tester - higher pressure should make the leak more obvious and easier to find.

Get a cooling system exhaust gas tester - the one with the blue fluid. Make sure it's a double chamber one to avoid false positives.

 

Is the underside of the oil filler cap "milky"? That's one sign of coolant in the engine oil.

 

It looks like you have at least the updated upper hose. That's the one with the nipple that has nothing attached. Has the water pump been replaced with the latest 3909 part number?
If not I would change it now since your in there.
One other thing is you still have the old failure prone 'Y" tube with the big square seams. This is a leak waiting to happen so I would also change that.




But I can't see where the leak is either. I don't see bubbles when my engine is running so not normal.
I would replace those parts and then pressure test the system when the engine is cold.

Let us know what the oil looks like and no I would not suspect head gaskets either unless the car has overheated badly sometime in the past?
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Thanks clubairth : WP Replaced 10k miles ago, 3/17. PN 3909 noted on the invoice but Jag/LR pump has a dif/PN and made in Italy. Invoice attached w/part #.
Does the Y tube behind the WP pop out or is it secured with screws? Otherwise, I don’t see accessibility without R/R of the supercharger.
1st good sign: Oil cap looks void of typical bad gasket-gray sludge. Will confirm oil condition soon.
Thanks to all of you for the addition suggestions and info. Most helpful and appreciated. I meant to do my pressure test before I started but, I had a “Senior Moment” and it slipped my mind as I started on it.

WP replacement 3/17 with part numbers.

 

Bubbling seen on the header tank whilst the engine is running could be a blown head gasket; unfortunate for such a low miles car, but can be caused by an overheating event. Are you the first owner ?

 

Your invoice has the right part number so your good on that and at least they changed some of the plastic stuff under warranty.

Take a look at Bigg Will's repair. Note on his early 5.0L SC engine those pipes are Aluminum. I sure wish Jaguar had stayed with Aluminum cooling parts and got rid of all this plastic failure prone stuff! He had an O-ring failure on his Y pipe I believe.
Water Pump Replacement

Yes the Y pipe bolts in and the SC has to come off. Which brings up another couple of things. Change the SC oil. Also there is another failure prone part at the back of the engine which is again plastic that will leak at some point and can't be changed without removing the SC again. So you would be ahead to do it all at once. In that link he also shows the rear water manifold he changed at the same time.
Plus since the dealer has already removed the SC before hopefully the alignment pins are not frozen. Please put some anti-seize on those pins when you reassemble the SC!

Finally check the SC snout for clunking and looseness. This another for sure problem although it's not a real serious one and other than the noise won't cause any problems for a long time. I currently have a small clunk in mine at 47K miles.
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Thanks for the info. You have been very helpful and kind. Luckily, the rear plastic manifold was replaced when they did the water pump and Y pipe.

I removed the intake manifold this morning and found some oil residue on top of the SC. Is this normal amount of oil residual from the PVC system or more than desired? I also noticed that the 2 of the 4 top intake bolts had not been torqued down properly. Not sure if this is significant.
I’m operating without schematics or manuals so, I’m relying on common sense and pure chutzpah. It looks like that won’t be enough though. I need a little more guidance with order of part removal. I would like to avoid the R/R of parts unnecessarily or in the wrong order. I see the rear bolts, the 6 top internal bolts and a few at the snout with what appears a hiding 2-4 more. Do I need to R/R the throttle body first? Loosen the top of the upper Y Pipe? Can I pop and prop up the SC to yank the snout? That’s the kind of help I need at this point. Thanks again for your patience.


Normal oil deposits on top of SC??

 

I have several manuals if you would like a copy?

With your latest picture I see your top plastic pipe also has the big square shoulders? Are you planning on changing that? When I had the water pump done under warranty they also replaced that pipe for me. I though that was standard when a Jaguar garage does that repair?

Normally the snout is glued so tightly that you need to remove the SC to get them separated. Be sure and use the proper sealant and it's noted in the shop manual. No gasket between snout and SC.
Does seem to be more oil than we normally see but unless you have problems I would just clean it up and reassemble. I have been told the large top gasket for the SC can be reused and it is about $80-$100. I put a new one in because all the factory repairs list as being replaced.
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HI, Unfortunately it looks like I am heading down the same path as QuietGiant here. On my 2014 XJ RWD 3.0. Last night I posted in this same forum asking for help finding a cooling system diagram or the step-by-step instructions on how to remove the water pump. (I downloaded the 2014 X351 "Workshop Manual" but there is no section for engine cooling!) Surely there is something that exists online or in .pdf that is similar to the old Chilton's manuals or American car mfg shop manuals?

I do have a couple of general questions, now that I have torn into it a little bit and realize just how complex the cooling system is.
1-Lacking an actual radiator cap, is it intended (or even possible) to completely refill the entire 10+ liters of coolant after a complete set of hose and crossover replacement by just filling up at the overflow tank?
2-Is there a vent that needs to be opened somewhere else in the system to allow for a faster, and complete fill?
3-I have read several places and seen the replacement parts (but not a diagram of where they go) that there are one or possibly two plastic crossover tubes between cylinder banks? Where are those and how hard is it to replace the rear one?
4-I have 70k miles on the car. There seems to be a consensus that the supercharger sealed oil need to be replaced?

Thanks very much in advance for any help!

 

I reviewed your original post and found that JBzxj40 responded with an excellent and detailed shop manual instructions to R/R the water pump. I found several online videos removing and replacing the water pump. Most were for Land Rovers with 5.0 but the procedure and parts are similar enough.
Your post didn’t explain what is leaking or what the issue appears to be. I suspect that you have a leak you can’t confirm it’s origin as I have.
If the leak is not from an obvious locations (front of the engine, visible hoses, coolant tank, pump, The odds are the issue will be the two plastic parts that will require R/R of the SC to replace. I thought my issue was the WP and my intention was also to replace a noisy SC coupler. It was only after I realized my issue was not the WP that things became more complex for me.
Your questions:
1 & 2. Once refilled, the cooling system will purge itself of air. Not certain that all 10 Ltr will drain. I just drained what I could and sopped up the over spill when I pulled the pump. My 1st challenge was removing the front slash shield to access the radiator drain. Before I put it back, I will cut an access hole with a removable port cover for future access. I’ll do the same for the oil pan drain. (Every few changes I prefer gravity cleansing.).
3. Not able to help there.
4. If removing the SC, yeah. Good idea to replace oil. Clubairth1, Fraser Mitchell, and Mark SF were all incredibly helpful (I will continue picking their brains). Please read their reply’s to this post. Hope this helps a fellow Arizona desert rat. 😎

 

Hi there Quietgiant, did not realize you were so close by!
You are right, I have not found what leaked and/or caused my car to overheat. I had not seen it on the first read, but later found the link above to Big Will's thread that clubairth1 posted; that seems like it is going to be VERY helpful. So last night I went out and tried to get a better look. I do not see any orange or other liquid staining on the radiator, the hoses up front, or around the water pump. After doing more searching, I now realize just how many different pipes and hoses there are for coolant in our cars, yikes! Assuming it was the water pump was probably wishful thinking.

The car overheated and it looks like nearly all the coolant came out somewhere on the right side (passenger side) of the engine, and from the middle on back. I am sure it was spraying all around in there somewhere, it got on the hot exhaust for sure. At first I got the awful impression that it blew a head gasket, but there is no sign of water in the oil, and no leakage that I can see when starting it up and running a little while cold. That is when I started trying to refill the system with water (to look for leaks) and got so frustrated that it looks like I am going to have to fill the catch tank about 8 times and wait for it to trickle down in. I am doing that with the engine off, as I am still scared just how much is damaged.

So this afternoon I am going to get a pressure tester with the screw on adapter, some fluorescent dye and a black light. I have been needing to remove the front bumper cover anyway to glue back one of the parking sensors that broke loose and is dangling behind there, so that will come off along with both bottom plates. (Love your idea about cutting holes in them for future oil or coolant plug access!). I was going to remove those last night, but my floor jack sprung a hydraulic oil leak. Sheesh, when it rains, it pours!

Thanks so much to you and the others for sharing info. I will take some photos along the way, and probably start a thread of my own on here.

 

Yes be careful refilling the coolant as the car is prone to trap air in the system. I have had good luck just cycling the car from hot to cold and topping up the tank as needed. But several people have had problems with trapped air.
Currently the advice is to use a vacuum filler if possible and most shops now use this as it's a great time saver too.

Also this comes up often but our cars use plane old Dex-Cool and you don't need any special expensive Jaguar fluid.

Yes if the SC comes off for sure change the rear water manifold and the SC oil. Read the link I posted above as Will posted a number of pictures. He had a SC V-8 but the SC V-6 is very similar and he does show the rear water manifold.
Water Pump Change
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Thanks to you too clubairth1,
Looks like we were both typing same time, LOL.
Yes thanks to your link I did read Big Will's excellent post. His idea about making the SC alignment studs out of bolts is probably going to save people HOURS of frustration. Also, on my V6 it looks like I have a ton more room between the back of the engine and the firewall to get that stupid rear plastic crossover out. (Which is now my number one suspect, but I will confirm with the pressure dye test.)

Thanks again,

 

My/2cents
To speed up your coolant refill efforts; Before reconnecting the upper radiator hose, pour your mixed coolant directly into the hose until radiator is full. Connect the hose and add to the coolant tank as needed.

 

Sorry yes both of us posting at the same time but at least we are both making the same points. So we are consistent!
Yes Bigg Will did a number of great posts and I am sorry he sold his Jaguar and moved on to an AMG MB. Which is also a very cool car.
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WP out of car. Looks fine, no signs of leaking coolant from it or the In/outlet tubes. Regardless, I’ll replace them with the new/improved design.
Only sign of prolonged standing coolant was at the right-rear (passenger) corner of the block (pic) that appears old residue from past heater manifold failure/replacement. There is coolant forward of there but I believe it was residual from removing the inlet tube.
The rear area of the block is coolant free.
The only sure sign of weeping is from the hose at the throttle body (pic) but, no enough to be “THE” leak accumulating below the front plate of the engine below the harmonic balancer area (pic).
As I stated before. Although I had the pressure test equipment ready to go, I had a senior moment and started tear down prematurely, my bad. Unfortunately I won’t do it until everything is buttoned up. If it turns out to be a HG, I won’t be tearing it down again anyway.
BEFORE I REASSEMBLE: Please let me know if you have any other opinions or ideas as to where this leak may originate. Any hoses, tubes, outlets. or gaskets I can expose and inspect without the pressure test? If I can eliminate the top of the engine as a source of the leak, that would be a major accomplishment.

 

Actually, you'd be surprised how much that little connection can leak. I'd definitely address that.

 

Is there anything behind the front engine plate that would leak? I believe all that is there are the crank, sprockets, chains and oil seals. All the cooling stuff if above that, correct?
BEFORE I REASSEMBLE: Please let me know if you have any other opinions or ideas as to where this leak may originate. Are there any hoses, tubes, outlets. or gaskets I can expose and inspect without the pressure test?I would like to eliminate the top of the engine as a source of the leak.

 

Off the top of my head, I can't think of anything that would leak behind the timing cover. Most of the cooling system is pretty much exposed except for that front Y pipe, the rear crossover, and the hose that runs under the supercharger.