Has anyone tried hooking the heater pump into an alternate location so that it would be accessible? I bought a new-looking pump on Ebay but really see no chance of ever getting the old pump removed. I am thinking of splicing the new pump into the existing heater supply hose located above the thermostat area. I will locate the pump in front of the air filter and run a wire to the original pump fuse location on the driver's side. Before I actually do this I would like to hear from anyone regarding feasibility.

I expect the new pump will provide minimal flow, but enough to provide at least some heat. I realize that the existing pump's impeller will create some resistance, but since it's not physically connected to the armature, it should spin freely.

 

Others with more knowledge and experience may disagree, but I think you're looking at a whole world of pain and frustration with that suggested course of action.
As you can see here :



the heater pump (item #7) doesn't work in isolation, there's a solenoid valve, various non-return valves, and a feed and return to the throttle body etc.
Although there's no physical connection between the impellor and the armature, there's a fairly strong magnetic connection and I'm not convinced the impellor would "turn freely" unless you installed a fairly powerful new pump.

The job isn't difficult - it's time-consuming, fiddly, frustrating and your back will hurt but .............. I think that would also apply to your alternative proposal.
There's an excellent thread by RaceDiagnostics on this forum (search on Heater Pump Replacement) where you can see exactly what is involved.
No specialist tools required except a cable operated hose clamp pliers like this :

https://www.bodyshop-tools-supplies....jxhRoCwqXw_wcB

 

Are you sure the pump is not working? My problem was the wicked bend in the hose that blocked the water flow. Improvised a plastic elbow and all is fine.

 

Today I checked the hoses going to the heater solenoid with a laser thermometer. The two on the left side (facing towards the rear of the car) are very hot (190° F.) and the two on the right side going to the pump and heater core are only luke warm (110°). This tells me the solenoid is not working. The pump and solenoid have a common ground, so a bad ground is a possibility. Another possibility is the A/CCM is not sending power to the heater solenoid. Also, there is no voltage going to the 10 amp fuse #15 that runs the pump. I measured it when the car was running and up to temperature and the heater blower was running with the temperature set to high.

The fact that there is no voltage at the fuse could mean another problem is causing the lack of heat. Anybody have a guess?

I swapped the heater pump relay with the fog light relay, which I know is good, and there was still no voltage going to the 10 amp fuse #15. Which terminals on the relay should I use to jump power to the 10 amp fuse? That's my next step I guess.

 

Have you tried manually adjusting the heat to HIGH and running.Also push the button for outside air temp and see what it reads.

My heater would only work when HIGH was engaged. The ambient air sensor told the Climate Control that the outside air was 132 degrees. No heat but Hella A/C.

The sensor is mounted under the front bumper cover.

 

I installed a tempoary pump in my XK8. A better piping diag is ---------->



You'll see the two water pipes coming out of the firewall (5 & 6). Install a replacement pump as close as possible to the firewall and disconnect pipe 5 from the firewall. Run a new length of pipe to the new pump outlet. Disconnect pipe 6 from the lower connection on the solenoid valve and run a new pipe from the solenoid valve to the new pump inlet. Plug the wiring into the firewall socket and you're done! You don't need to remove the old pump and disconnected pipes. The pump is 'double insulate' and does not need to be earthed.

Schematic is ---------------->

 

You should have +12v on pin 3 of the relay which, when energised, sends that 12v out on pin 5 then via fuse #15 to the pump.
The relay coil gets +12v on pin 1 when the ignition is on.
It gets grounded (i.e. energised) via the ACC module. This also supplies +12v to the solenoid.
If you bridge pins 3 & 5 on the relay socket, in a very quiet environment, you should be able to (just) hear whether or not the heater pump is working.

I would be wary of trying to connect +12v to the solenoid valve, unless you can isolate it completely from the ACC module and even then, I don't know if it is either 'on' or 'off' or whether it's more complicated than that, and it sort-of oscillates according to the input from the ACC module.

 

Thanks for the suggestions and the diagrams. Since it is now too cold and I need heat, and I enjoy driving the car so much, I will attempt to disconnect and bypass the water valve hoses and see if I can get some heat. If that works I'll know the valve is not functioning. I'll install a manual ball valve in one of the lines for when I need a/c next summer.

 

I have the intake manifold off right now and the reservoir out, so having the throttle body out of the way obviously helps. I removed the entire assembly (on bracket #13 shown in post above) after disconnecting the hoses. There are just 4 nuts holding the rubber isolators. Top two are very easy to get to, the bottom two can be accessed fairly easily with a universal joint on a 1/4" drive with long extension. Certainly no need to remove the cat or exhaust pipe. Plan on new hoses while you are at it, and something like Indian Head sealant on the heater core connections just for good measure. There is one hose that has a "flattened bend" by design.


Just an update, I reinstalled mine and it went pretty smoothly. I always take a photo at various stages of disassembly, and that really helped with hose routing in this case (what goes over/under/or in-between).

 

I test drove the car tonite and the heater will cook you out of the car!! No aux. pump needed. I bypassed that pump and the electric valve. The only thing I needed to remove and reinstall was the coolant tank. I will install a manual shut-off valve when I need a/c this summer.

 

You can repair the pump motor and this link will show you how.

Link.http://www.jagrepair.com/HeaterPumpMotor.htm

Hope this helps.

Gus
www.jagrepair.com

 

Thanks, Gus, I purchased a pump that works, but didn't use it. When you connect the heater hoses directly to the heater core, the engine's water pump has no problem supplying plenty of hot water. I need to add manual ball valve to cut down the volume a little.

Something in Jaguar's original design layout causes a huge reduction of water to the heater core thus requiring the aux. pump. Eventually I will return things to stock and replace the electric heater valve.

I have a similar electric valve on my pickup truck for the evap canister and that failed after 9 years, so I prefer the old style vacuum operated valves from the 90's that seldom were a problem.

 

I am glad to hear you have heat, but a word of caution, unlike most cooling systems ours are high flow/low volume systems. Diverting the cooling water the way you have done may be creating hot spots elsewhere in the engine. The engines do not like excessive heat and the results can be punishing. Good motoring and good luck.

 

^ Also, some engines/cars have histories of blowing heater cores at high revs when the heater lines are unrestricted. Early Ford Mustangs come to mind, for one (but definitely not the only one.) Ford even had quite a few TSBs regarding them and supplied restrictors to be installed. Nothing like having near boiling coolant pouring out of the heater case while driving.