Auxillary Coolant Pump X350 2005 XJ8

I am not clear exactly why Jaguar put this small pump into our engine bay.It is located pretty much ( as in not visible at all ) out of sight , and is located below the coolant resevoir. I read that it is visible if you remove the RHS fog light, and suspect that it is the cause for my slow coolant loss!? I also believe that it costly to replace…made by Bosch…go figure!! If you have any info to share I would be happy to “listen” ! TIA, John H, ON, Canada.

Its presence is to guarantee a full flow of hot coolant through the heater matrix.

When the engine is turning under 2,000 RPM at highway speeds, without that pump, cabin heat suffers…

If it is leaking, temporally bypass it. Seek out and replace it as soon as practical. You’ll notice the difference whenever you are not racing the car.

Hi Michael S , Many thanks for yr reply. That explains why its there. Are you able to give some advise on the best way to access it for servicing? Thanks, John H.

Not a clue from first-hand experience. Other things failed (door latch cables) on my X300 and X308 first. I let a local mechanic deal with the shaft seal failure on the engine’s water pump.

Generally, it was unbolt and unclip anything between open air and the offending part. I had quite the pile of bits and piecs when the throttle plate fully closed stop wore out.

If you can find it, keep digging until you can reach it. Sometimes, if you google your Year, Make, Model and Problem, sombody on teh intarwebz has posted a blog entry.

I had that issue on my X300 the culprit was the rubber house on the block side of the pump has a pinhole leak which was hitting the exhaust and disappearing without a trace. Get it up on a hoist and check.