I have a 1998 XJ8 - great car but with no heat. I have changed the pump and the valve - still no heat. All the relevant hoses (the octopus?) are hot when the engine is up to speed (into the pump and out of it). I have even changed the control panel inside the car - still cold - lots of blowing but no heat !! All that seems to be left is the matrix. People on the forum talk about "back-flushing" which I understand. I don't see how or where to "back-flush" the matrix when there are several non-return valves in the system. Any help/advice would be appreciated. I am reluctant to book into my local Jaguar dealer (Taggarts in Glasgow) I suspect that their labour rates would cost more than the value of the car.......HELP - Kenny

 

I have been messing about with 'no heat' issues on my XK8 for ages! New pump, rebuilt valve, flushed matrix - nothing doing. Eventually replaced all hoses and it works, so I'm not sure of the cause (stuck NRV or collapsed inner pipe wall).

The diagram is for an XK8 but the XJ is almost identical. You can see the two feeds into the bulhead - put your finger on each as the car warms up. #% is in, #6 is the return. If they get hot then the problem is within the car (stuck flap etc). If they stay cold then pull them off and flush water through. If they still stay cold after that then it's the pipe(s).

 

Thanks Jim - how do I sort the flaps if that is the problem ? Kenny

 

I have been told that it's a 30 minute job under the dash - but I've not done it because it's always been the heater pump that has failed.