Losing water

[ash.marston237]

Hi
I have a 2009 XK which i have owned for a month. The coolant low warning came on so topped up the expansion tank (the water level was right at the bottom of the the tank). A week or so later the same problem - coolant low warning, expansion tank empty. This has now repeated again. There is no evidence of water loss on the floor under the car (it does not get used every day).

Any ideas anyone?

[JimMann]

Hi Ash, If your car is parked up in a garage, depending on the garage floor covering it may be difficult to spot where the leak is manifesting itself, especially if it is a very small amount as you suggest. If practical, I suggest you cover the garage floor underneath the engine bay with newspaper or similar. In this way even if the leakage dries before you can spot it, the paper will have crinkled to show the approximate location. Of course leaks have a habit of showing up somewhere far away from their starting point.

You could take it along to a local garage and have them place the coolant circuit under pressure, they would have the appropriate equipment to make that happen and even if nothing is immediately apparent, it could be left pressurised overnight to see if there is any loss of pressure, therefore coolant in the interval.

Have you checked for any small cracks around the expansion tank, being plastic it can be susceptible to micro cracking, which may be difficult to spot, but again a feeling of wetness is a giveaway.

On a lighter note, welcome to the wonderful world of Modern XK motoring.

Jim Mann

[Dave Eynon]

Hi, my XK8 had a small water loss that never appeared on the floor as it only occurred with the system under pressure and the water pooled on top of the engine hidden from sight.
It was all to do with the thermostat housing and the seals associated with it that were becoming aged and needed replacing. In my case I also took the opportunity to upgrade to the aluminium housing although the original plastic unit was still in excellent condition.
Hope this will help or at least eliminate a potential leakage source.
Dave

[ash.marston237]

Thanks to you both for the replies. Helpful and will keep at it.

It makes my E Type seem a very simple proposition. At least I can see most of the engine and its ancillaries!