Yes, me again
Can't seem to locate any "how to" manuals on replacing the water pump or electric auxiliary water pump on a 2002 XK8 Jag. While my car's core temperature seemed to be fine (stable), the heater just wasn't putting out enough heat at high speed. Low speed seemed to be OK.

I knew I had a small coolant leak at the base of the metal thermostat housing (visible and could smell) so I decided I would tackle that first since I was losing coolant. Replaced the thermostat while I was at it (despite testing showing it was functional).

Worried now after gleefully reading Jag Forums over the morning coffee that my problem may also more likely be the auxiliary water pump. Having not been able to find a clear cut post/thread on this I thought I would put out the APB.

Many thanks in advance for any assistance.

 

Found this after doing a little more research for the aux water pump. Seems easy enough.

http://www.jagrepair.com/images/Auto...terPumpXK8.jpg

 

OK, and here's the water pump info. Guess no responses just meant I had to look harder.

JagRepair.com - Jaguar Repair Information Resource

 

Yeah, not so easy apparently. I have seen posts indicating this electric water pump is located at the back of the engine just above the transmission along the firewall. Really? Does anyone have a set of instructions on accessing it? Looks like a heck of a lot of coolant hoses to remove to get at it (if that is actually where it is). I would really like to replace it while the throttle body is off. I was having issues with heat during the winter but no issues with the engine temperature and no overheating so I have ruled out water pump and tested the thermostat. Anyone?

 

Correct - the Heater Pump and Heater Valve are neither easy to access or to disconnect.

The following schematic shows where they are in the overall A/C + Heating & Ventilating system:

JAGUAR XK8 - Heater Pump & Valve Component Location .pdf

See items 8 and 9 for the Heater Valve and Heater Pump.

With the Throttle Body out of the way, access is easier but the Expansion Tank must also be removed to reach the Heater Valve. Remove the isolation mounting nuts and rotate the valve forwards to get to the mounting nuts.

The hoses have to be disconnected next and the various clamps are awkward to understand when they can't be seen properly! The following schematic from JTIS makes this clearer:

JTIS - 2002 Heater Water Pump & Valve.pdf

See Page 4 for detailed drawings of the Cobra and Norma Clamps.

Cobra Clamps can be released and refixed with pliers but Norma Clamps need a special tool.

Note the direction of the one-way valves. You may be lucky and find you haven't got component failure but either the Heater Pump, Heater Valve or one-way valves are blocked with debris from flushing the cooling system.

Graham

 

Many thanks Graham. One question, once removed will it be easy to identify and remove the debris? I have already ordered a replacement pump but not a valve. Will likely install the new one to be safe but don't want to throw out a perfectly good pump if I can clean it up. Cheers.

 

The pump is not a direct drive from the motor and at times the pump section will jam resulting in the pump motor running but the pump not pushing the flow of water/coolant. This will show you the pump section JagRepair.com - Jaguar Repair Information Resource This pump is from my x300 but they are the same. If the motor seems to be the problem you can rebuild it. Most of the time the problem is the motor brushes. You will not find an exact fit for the brushes but you can get a near fit from Radio Shack and sand them to fit and you will be up and running. I hope this helps.

I am assuming that you checked power to the pump first.

 

Timothy,

You can certainly flush the hoses, pump and non-return valves. I don't know about the Heater Valve. It may need to be energised to flush properly.

Graham

 

Hi - I have a leak behind my water pump - planning to tackle it later this week. Not sure whether there is or isn't an O ring as well as the gasket- can someone tell me so I can order the parts?? Thanks in advance!

 

No “O” rings just a gasket. I elected to use the Jaguar pump so the gasket is metal as you can see in my write up on my page.

 

Hi Gus,
By power are you suggesting there might be a fuse that has gone? It had worked properly for the last couple of years until start up this spring when I seemed to lose a fair bit of coolant. I think I have looked for all the usualy suspects (thermostat tower, water pump, hoses) but the only place I could see a small leak was at the base of the thermostat housing. Also, no coolant has continued to leak under the car since start up.
Anyhow, I will look at the pump and see what I can see.

 

I guess I was assuming that the pump was not working as well. A poor assumption on my part. I am dealing with a major tooth ache and the meds took over…….. Keep up the good work!

 

Take 2 and call me in the morning I am thinking there is a chance that the pump is not working but not sure how to test it. Once I have the throttle body and the thermostat housing off, was thinking I may as well replace the aux pump too. But seriously, there wouldn't be a fuse of anything I should have stupidly checked first? (Insert fear and frustration here).

 

You can test it on the bench but expect you'd prefer the answer before removing it from the vehicle? As you know, it's well buried and the old trick of using a long wooden handled screwdriver is the only way I can think to get at it with the Expansion Tank in place. Touch the end of the screwdriver on the pump and hold the wooden handle lightly. You should be able to feel vibration if the pump is running.

To dispel 'fear and frustration', check 10amp Fuse No 15 in the Engine Compartment LH Fuse Box.

Graham

 

Cheers Graham. Will have to try testing it on the bench with everything already apart. Fuse checks out so thanks for that. I slept better last night Now we play the waiting game for the parts to arrive. Will report back on the trials and tribulations of replacing an auxiliary heater water pump. A few days ago I didnt even know I had one so thanks Jag Forum.

 

We have two things going on one is the leak at the engine water pump and the other is the pump for the heater no heat.

The engine water pump leak is a matter of finding the source. Just remember that the flow of water can be deceiving it can be from the thermostat housing to the x-over pipe. I suggest that you take a good look at the problem before replacing everything on a shotgun approach. Be cautious not to put your hands in the engine compartment with the engine running.

As for the no heat it is often the HEATER PUMP that is clogged or the heater core or associated hoses in either case you will need to look into it. If this heater pump is not running you need to check power as suggested by Graham if the pump is running but flow is still low you may want to pull the heater pump and see if it is clogged. If the pump has power and the pump is not running then rebuild it or replace it. If the pump is running with no obstructions then you may need to check the heater core for an obstruction. That can be done by connecting a water hose to the heater core pipe and flushing it out but be sure the other end is open to allow the flow of water.

I hope my meds did not kick in and I did not confuse you. My appointment is Thursday PM!

 

Nope. No confusion here. Sound words of advice in fact. I will your path of elimination. Heck, I might even try your meds if your sharing . If it makes you want to stick your hands into an engine while running though, I think I'll pass. Thanks again guys.