Last year I purchased a 2000 XK8 in Phoenix and brought it to Minnesota. While driving it to heated storage last November I noticed that no hot air was coming from the vents even though the auto temp was set to the highest level.

Since it was an Arizona car I suspect the heat was not used much if at all. However, as one would expect the AC works well.

I did check for Climate Control System error codes. None registered. While reading a British book on the XK8 I noticed that the water valve assembly is commonly at fault when no heat is available.

So I have purchased a used valve and will shortly install it.
I am concerned about the tight space available to get at the valve. So before I turn a bolt I want to check with the forum group and see if anyone has previous experience and a technique for removal and installation of the valve.

Any advice would be much appreciated.

Tom
2000 XK8 Convertible
　

 

I have just finished doing the same job. I changed the heater pump and tested the water valve. Not sure about a US car but a Scottish XKR I had to take the throttle body off and the header tank, but that was it. I just took the hoses off one by one, there is only two nuts to remove on rubber mounts that holds the whole water valve/heater pump assembly.

I had the same problem no heat from the heater but it was the heater pump brushes worn down to nothing. I check both pump and valve with a bench power supply to find my faults.

 

Thanks for the information. Good advice. I will test the heater pump also.
I will add another reply when I get this done. Hopefully next week.

Tom
2000 XK8
Convertible

 

You've worked in those really tight places where getting spring hose clamps off with regular pliers took many choice words, left your knuckles bloody, and took way longer than it should have? --> Just like the heater valve/pump/octopus behind and under the throttle body on the XK8.

The best damn hose clamp pliers I've ever used. (click this link for Sears to get to the picture)
Sears: Online department store featuring appliances, tools, fitness equipment and more
I almost didn't buy them for that much money but having been back behind there several times now and used this on other rigs I wouldn't do without it.

And yes, take the TB off first. Time well spent in making the job faster and easier.

 

Just because I had to do this after I replaced the heater octopus hose assembly on my XK8:
Have you had the engine over 3000 rpm with the heater controls on (not AUTO) with the temperature set at max temp? If the coolant has been drained and air got into the heater core plumbing it will keep the heater from making hot air. So, before you turn a bolt:

1. Completely warm up the engine
2. Set HVAC control, A/C off, one of the vent controls on
3. Temperature to max (90?)
4. In PARK, ease the RPM up to about 3000 and listen for a gurggling sound under the dash. That would be the air being pushed out of the system.

This might save you a round trip to behind the engine. If it doesn't fix the no-heat problem you haven't lost much except time.

 

Ok!
Great Sears tool. I had not seen that before but I can see its benefit in a tight spot. Just ordered it,

The water pump has been changed at sometime in the past so it is possible that air may be in the system.

The XK8 only has 70,000 mile on it. I have put just 2,500 mile on it so there may other issues that pop up. All is to say that I am impressed by the 146k you have achieved. A tribute to you and the manufacture.

Thanks and stay tuned.
Tom
2000 XK8 Convertible

 

Ok. As a follow up ----- sure enought wouldn't ya know it that the water valve was not the problem, So it may be the water pump brushes. And no air in the system. I will go down the check list for insufficient heat under the Climate Control System catagory.

Tom
2000 XK8 Convertible