Hello fellow slaves to your cars;


My 2002 XK8 has been loosing cooling fluid at an alarming rate (~1L per drive) but hardly any when off. The coolant is dripping out the right hand side wing just behind the wheel arch.


I pushed the wheel arch lining to one side and found a black plastic pipe (pics), through which hot water leaks out when the car hits temperature, and hot water/steam gushes out when the enjoin is turned off when warm.


WTF is that tube and WTF is it doing that?

 

That is the overflow reservoir. It isn't sealed and pressurized like the rest of the system, it's just a place for the extra fluid to go when it pushes past the the pressure cap.

There should always be some amount of fluid in it and the tube should be submerged, the idea being that the overflow goes into there when the engine is hot and as it cools down is sucked back into the reservoir up top.

My guess is you have a bad pressure cap and it isn't keeping the system at the right pressure so it's ALL coming out the overflow.

Not having pressure in the system is a serious risk for overheating as that will let the antifreeze boil inside the engine, so something to check and get fixed fast.

If you don't mind not having the Jaguar leaper on the cap, they can be had pretty inexpensively.

 

Hi,

what you are looking at is the "overflow pipe", number 17 on the linked picture:

https://www.dropbox.com/s/mycxabeymk...erflowpipe.png

As I read the description of your problem ... , some time ago when I bought an XJR I had a similar problem. The cause of it was that someone swapped the hoses connected to the expansion tank. Check if they are all connected to the proper place.

good luck.

 

And that bottle should have very little coolant in it. If its full cold it will push out the excess coolant on the ground.

 

I've checked the expansion tank cap and it doesn't look healthy at all; warped and missing ALL it's gaskets! I guess that would be the first point of attack then.

Thanks guys!

 

I had the same problem.Fitted a new expansion tank cap from an auction site for £8 and it cured the problem.Good luck with yours.

 

Ok, so we have a spanking new cap fitted with fresh looking rubbery gaskets. The problem is improved, but not completely gone. Loads of coolant is still escaping, a bit slower, but I still need to top up after every drive.

Water still drips from the overflow pipe and when I open the cap I see water between its two gaskets. I recon this means that there too much pressure in the cooling system, causing the pressure valve to open.

I guess that too much pressure it probably due to a faulty water pump or a jammed thermostat. Any idea how to check for those? Any thing else to check for?

MJ

 

If your XK reservoir is similar to the XJ reservoir, there are two pipes at the front that need to be crossed over. If they are not, then the coolant starts getting pushed out. Mind you that presumes it is the same system as the XJ.

 

I think the pipe you're referring to is not used in my car. The expansion tank only has 3 hoses connected to it (including the big one at the bottom). See pic in this post: https://www.jaguarforums.com/forum/x...90/#post622461