I know you may find this hard to believe, but I've developed a coolant leak on my 2010 XK Coup. This is the 5.0L Naturally Aspirated engine. At first it was just adding coolant when the car would give a "Coolant Low" message on the dash message center. It would happen every couple of weeks. It seems to have gotten worse. I will attach pics which show a spray pattern of the salts from the antifreeze. I may be wrong but to me it appears to be the water pump (another shock.)

 

Stop driving your car, you risk cooking your engine, seriously.

There are several plastic pipes that could be
causing this. Might as well change the waterpump
while you are in there.

 

What year is your XK and how many miles on it. Coolant pump and piping failures are relatively common for early 5.0L production cars. They are known to fail at 35 -50k miles. Tyrkam is correct. Get your XK into service now. There are metal pipe replacement for the plastic oem pipes that can be bought on Amazon. I'm not sure the metal pipes will fit the 5.0L NA engines.

There are multiple threads on this issue for 5.0L engines. Use the search box above in the upper right corner to research the issue. In at least one of the threads you will find the correct part number for the latest iteration of the water pump. If you want to be on the safe side; do not drive your XK until you address this issue. The penalty for leaving it go too long is very expensive.

 

It's a 2010 XK with 89,400 miles. It had a water pump last replaced within a year of its first owner about 10-14K. I was watching Youtube videos with my son to see if we could replace the water pump ourselves. The only part that looked difficult was reapplying the Serpentine Belt. Of course the hoses may be at fault here. I have it lined up to go into one of the only independent garages locally that will work on Jaguar. I don't know why most shops won't touch them.

I hope I can get metal parts to replace the plastic. Using plastic parts on an $85K sportscar is pretty pathetic.

 

Current part number on the water pump is AJ813909. I have no idea how good it is. The recommended water pumps were replaced several times ending with this part designation.

 

At 89,400m well worth checking all the idler bearings for wear with the belt off.
There is no alloy forward CW pipes for the 5.0Ltr N/A engine.(yet)
If you think changing the Serpentine belt is difficult, may be using a competent jaguar independent mechanical would be safer.

I don't know why most shops won't touch them.?
Liability for the repair/job, go in there and break something or something else breaks afterwards.

Would it not be better to remove the air inlet duct and check/ confirm what is going on/ leaking etc?

But if in there, water pump, vent nipple to water pump in brass (non JLR) you may well break it anyway removing.
The alloy connector behind the CW pump to oil cooler, also alloy non JLR and the 2 seals.

Thermostat and housing. usually getting a bit old by now, and the top cover seal could be leaking/weeping, Alloy housing copy available for this and is more accessible when changing the water pump.
The vent line back to the expansion tank is also prone to breaking at the hard plastic pipe section. (just replace that line with one piece braided silicon hose)

Using plastic parts on an $85K sportscar is pretty pathetic.

Lighter, cheaper and has built-in repair renewal requirements to increase profit. The car is under warrantee by JLR for the warrantee period not for life or in excess of 3 years, without additional remuneration. A lot of items (plastic) break during this period and are replaced FOC is you don't damage the engine by driving on with no coolant, or over heat the engine.

So buy your 85K car for much less and read all the forums, and cure all the issues with up graded parts in advance. Better and cheaper if you can DIY, but a dying art apparently.

 

Thanks for everyone's help so far!
Bydand-
You make a lot of good points in your post.

If you think changing the Serpentine belt is difficult, may be using a competent jaguar independent mechanical would be safer.

The only time I have removed belts is on an old Isuzu Trooper 25 years ago that kept running though alternators. It could be relatively simple to replace the belt, but it's something I've never tried. I only performed my first oil change 3 weeks ago and my first brake job last weekend. I am learning DIY but apparently not as quickly as I could to handle repairs.

Would it not be better to remove the air inlet duct and check/ confirm what is going on/ leaking etc?

Excellent idea. I had planned to run a pressure test to see if it would reveal the source for the leak.

But if in there, water pump, vent nipple to water pump in brass (non JLR) you may well break it anyway removing.

Yeah, that's the rub. I saw a YT tutorial where the guy broke several things while trying to remove an XK water pump.

Thanks for giving me areas to search and determine/replace based on age.

The "plastic on an $85k sportscar" was me venting because I was disappointed. Obviously, I paid nothing like $85k for the car, and I have been watching hours of repair videos and searching the forum to get up to speed.

Better and cheaper if you can DIY, but a dying art apparently.

I've been actively working on DIY repairs and hope to continue to learn. This forum has been invaluable to me.

 

The wise man learns from the mistakes of others!

I would suggest the Jaguar 5.0Ltr engine is a little bit more fragile than an Isuzu Trooper of 25years ago, and certainly less forgiving of the unwary. Things have gotten a lot cheaper, and weaker in the interim.

The water pump is held in by 4 x M6 screws for example, easy to over tighten, and/or fill the thread hole with grease and strip the threads. As well as manhandling the release of the coolant water pipe clamps to get it out.

You will build knowledge as you go on and practice, but small steps and build your confidence first.

Sorry just saw this post under this. Good picts of the thermostat housing weep/leak, and some other details. Its for AJ133S, but most things a similar to the AJ133 5.0 Ltr NA.

https://www.jaguarforums.com/forum/x...g-part-276978/


This forum and others, together with you tube have a wealth of information.

As an aside, just have look at the (inside) of air duct inlet to the throttle body where the clamping clips sits. I see you have a rubber collar on yours. Mine, on the 3.0SC AJ126S had cooked the plastic throat of the duct where the clamp sits. As 10mm from the water pump and rather hot apparently. Making the plastic hard brittle, and some flaking off leading to air leaking in. While you have the duct off, (as they say.)


Nice rubber boot over your one so my be OK.

 

My son and I removed the air inlet duct to get a better look. We saw a small amount of coolant in the tray below the motor in the front of the car nearest the radiator. We attached a pressure tester to the coolant expansion tank. It held at 16 psi for several minutes without any dropping of the pressure. Unfortunately, neither of us could detect where there was a leak. This is an odd case where if the hood had been connected to the passenger cabin instead of front of the car we could have gotten closer to everything. Where I checked the water pump area was dry. I am hoping this means it might be minor at this point. We reinstalled the intake ducts and I will have to go with an auto shop I guess to look at it.

 

It is difficult to find the leak/ weep with the pressure test. The leaks like heat, hot engine and a bit of engine load and revs.
Sounds like it is the front of the engine, water pump from the tell tail, or the thermostat housing top cover seal leaking.

So long as there is no CW in the V of the engine it is less likely to be the forward cw pipes, or oil cooler.

Next best option is to remove the engine under tray take a spirited drive and put it up on ramps and look up from below to the water pump and thermostat area.

 

Well the car is in the shop. They said the problem was the thermostat and the plastic housing it was in. The mechanic said the water pump was good, however, once he changes out the thermostat he wants to see if there are any further leaks which makes sense to me. It's going to be mighty expensive. I probably could have changed out the thermostat but I just couldn't determine where the leak was coming from.

Off Topic: They had a bunch of Jags in for service including two XJS 12 Cylinder models. I much prefer the E type to the XJS (one reason I love the XK is that it returns to the amazing curves of the old E type) but I have to say they were quite fetching.

 

. Our cars cooling systems fail predominantly in this order. Water pump, front crossover outlet, thermostat housing, and the notorious and pain in the *** rear crossover. Most plastics over time are going to fail. Rule of thumb… once you are in there… try to change as much as possible. You’ll be kicking yourself when you have to go back and take everything apart again.

 

Hopefully you didnt take it to the dealer. Tell your mechanic you want a 2 piece pump like linked below. We have this pump on both of our XK's. The 3 piece pumps fail faster than the 2 piece ones due to the extra seal.

 

I took it to an independent shop, but it's the shop the dealer recommends for Jags older than what they will work on. Almost no-one else in Birmingham Alabama will touch a Jag except for brakes, oil changes and things like that, but I do those things myself to save on maintenance costs. I will look into the part you referenced. Thanks for the advice!

 

The OEM Jaguar water pump has been revised numerous times, the latest revision was in 2015, part number AJ813909 I haven't noticed (at least on this forum) failures for this latest pump. I had mine done (under extended warranty) years ago. So far so good. Good luck.

 

I got the car back this afternoon. I asked him about the hoses. He said they had all recently been replaced and are in good shape. He said the thermostat had been replaced as well, but it was a "low quality" part that failed. He replaced a minor leak from the exhaust tank and put it under pressure but all else was good. I washed and waxed the car and will get to spend more quality time with it this weekend. Thanks for everyone's help!

 

Had the car out for a track day and three laps in…boom!

Still can’t tell where the leak came from. Track officials think there may have been oil loss too due to the coloring of the fluid left behind (assuming it was mine.) Am thinking the oil cooler hose may have gone and at least one of the radiator hoses. I need to open it all up and see what it looks like in there.

 

Did it overheat or were you able to stop the car before it did?

 

Yeah, it overheated (or so it appeared). I cut the motor very fast and rolled back into the paddock. I let it sit an hour and then began to try and see what was going on.