Heater pump check/removal

[xjscharlie]

Hello Folks,
The heater performance on my 2000 4.0L X308 has reduced; there's still some heat there on "HI" but way down on what it was. Wanted to check/remove the heater pump if necessary. Has anyone done this? Suppose its possible to check that the pump is operating? Looking for advice i.e., Do's/Dont's in order to save unnecessary work? Any help appreciated. Charlie.

[BrianG]

When I had a 308 I had to replace the carbon brushes in the motor a couple of times over the years. This is the usual mode of 'failure' for these pumps: the brushes just wear out, it's running time not mileage that does them in. The motor can tested without removal if you can put a multimeter across the connections when it's unplugged. From memory it should read a just few ohms. If you don't get a reading then the brushes have gone.

Jaguar don't do spare bushes but they can be repaired if you are willing to make new ones. The motor can be removed without draining the cooling system if you can get to the small screws that hold it on to the pump body itself (it's magnetically coupled to the actual pump impeller). You can sometimes get suitable spare model motor brushes on eBay, but I have shaped a couple of replacement sets now from slightly larger vacuum cleaner brushes, cut down and filed to size. You need the types that has embedded copper braid wires in the brush as these need to be soldered to the terminals inside for good contact. You should find the remains of the original ones to give you a guide for dimensions of cross section to file down to. Whilst not as hard material as the original brushes, these should typically last around four or five years before needing to be done again. A lot cheaper than a new pump assembly from Jaguar!

[xjscharlie]

Thanx for the prompt reply. Can you get to the motor without removing the top tank? What do you have to remove? Rgds.

[BrianG]

Thanx for the prompt reply. Can you get to the motor without removing the top tank? What do you have to remove? Rgds.

Unless the 2000 model is different to the one I had (1999) the pump assembly is rubber mounted on the left side of the car on the inner wing, close to the bulkhead. So no tank to remove, but the access can be a bit tricky down the side of the engine if you have large hands. If you don't mind draining some coolant (I siphoned some out of the header tank the first time I did this job) it's fairly easy to then unship the whole assembly without making too much mess. Undo the pipe clamps from the pump and then undo the bolts on the rubber mounts. I did not bother doing this the second time as I knew what to expect, so just undid the motor from the pump.

[xjscharlie]

Thanx Brian the pump appears to be working fine so i'm suspicious that the matrix may be partially blocked therefore intend to back flush it. Wondered if anyone had done this recently and can proffer advice on the correct inlet/outlet pipe connexions. Looks like the pipe on the side of the pump is the inlet but need to verify the outlet connexion to go directly thro the matrix as there's also a valve in the circuit. Rgds.

[Andy P]

Hello Charlie,
Haven't had to do this job myself.
But have a look at this thread.
Third post in has a diagram for the hoses:
It might help a bit.

https://www.jaguarforums.com/forum/xj-x ... at-152065/

Take care.
Andy

[xjscharlie]

Thanx for that. I had retrieved a diagram from my CD so should be able to disconnect the right hoses and back flush it thro. The heat loss has been gradual so hopefully back flushing will effect an improvement. I had the same problem with my XJS V12 a couple of years ago so i disconnected the inlet/outlet hoses and filled the matrix with a strong solution of caustic soda and left it for 2 days then flushed it and what a difference. Somewhat of a relief as changing out the matrix is a huge job. Rgds. Charlie.