Hi,
I’ve spent a large chunk of today trying to fix the lack of heat in my XJ8, I suspected the auxiliary pump. I dropped the coolant then set about getting access to the pump, I’ve got a few spares so I decided to make a good one out of a few bad ones. I dismantled my pump and found the bushes worn right down, so I opened the others and chose the one with the most meat on the bushes. I then greased everything that moves and put it back together, operates like a champ now. I put it back in the car and put everything back together. At this point I should’ve tested the system, but didn’t because I was rushing to get onto the next thing on my list. My fault, but I later discovered I’ve still got no heat. I now suspect the heater valve.

However, I’m also convinced I’ve put the pipe from the auxiliary pump to the valve on wrong. Which way should the one way valve go? Should the arrow go to the pump or to the valve? If someone could answer that question I’d be very grateful.

So so now I’ll have to spend next Saturday messing round to replace the valve and hope that’s at fault.

Thanks,
Stu.

Thanks for the info, my heater works it was a case of either I had heat or didn’t. Over 2000rpm I’d get heat as the engine pump would be under enough load but below that it’d be cold. However sometimes I’d just get cold constantly, but as it’s been unusually hot in the uk I was using AC a lot. But looking at the bushes on the motor it was suggested that it would only work on the odd occasion. I’ll just have to swap the valve out next Saturday.

Looking at the diagrams Eric provided me I have put my valve the wrong way, I feel foolish.

Ok so after spending a week driving round with no heating, I got a chance to fix this today. I pulled the valve out and replaced it with one I opened up and refurbished, I then blew air (from my lungs) through the pipes to the matrix which pushed the water through. I then reconnected everything using traditional Jubilee clips instead of those silly clips the factory used which I always have trouble with. Still no heat.
I ran the codes on the HVAC and got one telling me the refrigerant is low, which isn’t a concern just now but needs addressing. I then decided to run the engine again and see if she’d burp.
I took the revs up to 4000rpm and finally got heat, and it’s been fine all evening. I’m feeling better now I’ve solved it, but I’m going to replace the thermostat next opportunity I have to work on the car. I may as well do this seeing as the coolant needs replacement with a correct mixture of OAT. It’s a bit too water rich currently and winter is coming.