My 2007 XKR is approaching 140K miles and having just booked it in for a service in a couple of weeks and told the mechanic there weren't currently any issues, I now have a coolant problem!

I noticed when I arrived at work yesterday and got out of the car, it was still making a LOT of noise and put that down to the radiator fan. After a few minutes it stopped. Never had that before! Carefully driving home in the evening on 60mph country roads and get an amber engine overheating warning, almost immediately followed by a red engine overheating warning. I pulled over straight away and turned off the engine and opened the bonnet. Radiator fan ran for about 5 minutes. I waited around 20 minutes, then carefully and slowly drove the remaining 5 miles home at around 30 to 40mph. Didn't get the warnings again.

Later, when the engine had cooled, I checked the coolant levels and they were very low, which explains the overheating and the radiator fan (which seems to be quite noisy - not sure if this is normal). I filled up the coolant (around 3 litres of 1:3 mix), wiped any signs of liquid away and went for a short drive. Checked again and the coolant level has dropped slightly and I can see coolant around the lip of the coolant tank, but nowhere else, and not on the floor under the car.

There are two pipes connecting to the coolant tank, and one of them seems a little loose. If it bends slightly I can see coolant coming out. Started up the engine and sure enough, flexing this pipe results in coolant escaping and leaking around the lip of the coolant tank. Here's a photo:






The pipe that's leaking is the one on the left and it leaks from the joint, which doesn't seem to be very secure.

Chances are I'll move the service forward and ask the mechanic to sort it, but I would be interested to know what the fix is for this issue. I'm not very mechanically minded, but willing to learn.

Thanks.

 

Very common failure point on the expansion tank, there's likely a crack on the inlet tube requiring replacement of the tank. It is not very expensive and easy to replace.

 

Thanks for the quick response jahummer.

I hadn't considered changing it myself but may look into it. I can see a replacement tank sold by British Parts UK for £79.76.

I had assume the pipes are held onto the tank by the clips, but what is the large screw type thing next to the pipe that is leaking?

Are there any instructions anywhere that I could follow to replace the tank? I assume it isn't an issue simply disconnecting the pipes from the tank, they don't need to be "bled" or anything before replacing to remove air? I've seen some info suggesting the pipes should be plugged to prevent coolant from leaking out.

Is it likely that replacing the pipes on a 12 year old car is likely to damage them, so they would also need to be replaced at the same time as the tank i.e. due to the rubber material becoming brittle?

I guess first of all, once I understand the above, I need to disconnect the pipe from the inlet tube that is leaking to confirm that it is cracked and that it isn't the underside of the pipe that is split?

Thanks.

 

You have to remove the screws, the 3 hoses and the intake to give you a little more room to slide the tank off of the bottom mount. I siphoned the coolant out of the tank and clamped the hoses without losing any coolant. No worry about air. For some reason that part of the tank always fails so I would be surprised if it is anything else. Mine was not leaking but I replaced it out of caution. When I slid the inlet hose off, I discovered the tube on the tank was actually cracked and only a matter of time before it would have started leaking.

 

You're lucky you didn't cook the engine, driving after the Overheat Warning like that. Most of the time, Engine Overheat comes on from a water pump problem, or drastic coolant dump, and driving even a short distance causes permanent damage.

 

Removed the hoses and saw the large crack on the inlet pipe:

 

The code on the tank fitted to my car is 7W83-8A080-AA.

I can see a couple of sites selling original replacement parts, but the last two characters of the code show AE, rather than AA. Also, these have foil on one side of the tank, but mine doesn't. They also state 140 kPa, whereas mine shows 120 kPa. I assume the AE simply signifies an "improved" version of the same part?

 

The last letter of the WERS indicates revision level. The tank fits multiple models including the F-Type, mine came with foil but it will May affect anything on your car.

 

Make sure your replacement has the two hose nipples. I made the mistake of buying one that only had one (from an F type if memory serves). I just T'd them together and it's been OK.

 

I guess I have officially joined the club. Driving yesterday when I get 'low coolant' warning. Pulled over and open the hood, steam rising like an expectant volcano. Towed and dropped at the dealership, will find out tomorrow how bad it is. Ugh!

 

Actually it should be three, two on the top and one on the bottom.

EDIT: T2R25157 is the newest part number for what you need.

 

Unfortunately I'm stuck!

I'm struggling to be able to release the larger hose under/to the side of the coolant tank. I managed to remove the clip using some long nosed pliers, but just can't get my hand in to pull the hose from the tank. Also, having removed the single bolt holding the tank to the car body, it wasn't possible to lift the tank out. Having received the replacement tank today, I can see why. It actually needs to be slid out, away from the wing towards the engine, however, there's a large solid bar in the way, so it won't slide far enough to be released!

Can the bar be removed? Not sure what it is for or if undoing the two bolts on the right will be enough to release the bar, or if it will also need to be released at the other end (near the windscreen). Is this bar under any pressure i.e. will it spring up/down/left/right if the bolts are undone.

Here's the bottom of the new coolant tank. As you can see it needs to be "slid" off.



And here's the bar preventing me from sliding the coolant tank any further so that it will release:



Any pointers would be gratefully received.

 

Phew! I've done it! Had to undue the two bolts on the brace bar, which gave enough play to be able to slide the tank forward. Once it was free I was then able to get more of a grip on the lower hose and remove it.

The new coolant tank came with a fitted sensor, which screws in under the tank. The old tank didn't have this sensor and there's no sign of a cable that would potentially connect to it, so I removed the sensor from the new tank.

This explains why I didn't get a low coolant warning before the engine overheating error. Shame really, as this would have alerted me to the fact that the coolant level was low. Not sure if newer XK's have this coolant sensor.

Jaguar cost cutting back in 2007? Like the electric aerial!

 

The 5.0L cars have the low coolant sensor. If I were you I would have left the sensor in and run a separate wire to it. That way you could just hook a light up to it and put it in the cockpit somewhere where you could see it. Simple job to do