Jaguar Forums - Jaguar Enthusiasts Forum - XK-RS auxiliary coolant pump.

Had the same on my 4.2 XKR. Pump is located on the driver's side end of the radiator (assuming a RHD car). You'll need to jack/lift up the car, drop all the coolant, get the fan cover panel under the front end of the bonnet out, remove the top two hoses from the driver's side end of the radiator so you can access the bolt holding the pump in place. Remove the undertray, you'll see the pump from underneath, remove the two hoses attached to it, trace the electrical cable back through to the engine bay and disconnect.

Refitting is, as they say, the reverse of removal, then you have to refill the coolant as per normal. It's a fiddly job overall, access down to the pump from above is pretty tight, the hoses take a bit of wrestling to get them off and the electrical connector was awkward on my car. If you're really unlucky the the hose clips are oriented in such a way as to make opening them difficult. I found it easier to remove the bumper completely to get access from the front.

As for upgrades, it's not as simple on these as on the older cars as the electrical connector on the pump is a hard-wired fly lead and the usual upgrade parts (Bosch for example) have different connectors, but not insurmountable if you're handy with electrics. In UK climates and assuming your car is not remapped or have other performance modifications, probably no benefit really in doing this.

One of the fuses in the fusebox in the engine bay runs this pump, worth changing that first, take the car for a short drive and pull and check the fuse. It kept blowing on mine so I knew the pump was goosed but you might get lucky and discover that's all it is. Check your handbook for which fuse you need to check. You'll probably need to change it once you do change the pump, assuming it comes to that.