[8bit]

Yeah, mine failed on my old 2008 4.2, I had about 90k miles showing at the time though. It's a pig to get to, the workshop manual doesn't tell you to take the front bumper off to change it but it'll be far easier if you do. There are some coolant pipes above it, going in and out of one of the radiators, you'll almost certainly have to undo those to get access to the securing bolt on top of the pump. The coolant hoses into and out of the pump are easiest accessed from underneath.

The electrical cable for the pump is a real pain; it runs in behind the radiators to a connector in front of the engine, assuming your car is LHD then it's just to the passenger side of the center line. Best way to find it is get the pump disconnected and unbolted so it's free apart from that connector, get under the car, see where the cable runs into, get a hand up to the other side of where the cable disappears and wiggle the cable on the pump until you find the connector. Installation is, as they say, the reverse of removal...

It took me several hours to change it but I'm by no means a skilled mechanic and I fought with it for some time before giving in and removing the bumper. I didn't find a lot of other people who'd had the same issue so I don't think it's a serious, known fault, but if you have to drop the coolant for something else anyway then it may be worth doing as preventative maintenance.

 

[8bit]

No the small electric pump is quite reliable. There was a possibility of an upgraded one on X100 cars for possible improved cooling. Not sure about the one on the 5.0

The OP has a 4.2 but from what I can tell it's the same part on the 4.2 and 5.0 cars. It's not cheap though; retail price in GBP is £385.42. I tried one of the Bosch ones that people used to use as an upgrade on the X100 but it won't fit without some work - it's bigger so the standard rubber bracket won't hold it and the Bosch pump doesn't have the flylead with the connector, so you'd need to make up some sort of wiring adaptor to power it.

 

[8bit]

First I knew about it was when I got a "restricted performance" warning on the dash. I checked for codes, saw one for a coolant pump issue but the coolant temp looked fine (checked with Torque Pro app and a Bluetooth OBD-II adapter). Noticed later that the intake air temperature was very high, like 85C. There's a fuse for the pump in the fuse box in the engine bay, it had blown so I changed it and went for a short drive, got the same warning and noticed the fuse was gone again and the fault code was back. I did some searching on here and other forums and found a couple of threads which all ended with the pump having to be replaced.

I managed to get a pump from a breaker from a 40k mile car, part number is C2C1314.

 

[8bit]

Sorry, to answer the question, "Could you still drive?" - yes but once the intake air temperature reached a certain value the car went into Restricted Performance mode. I believe that when that happens, the bypass valve for the supercharger opens and the engine RPM is limited to about 5000 or so, to prevent the intake air temps getting any hotter. I'd limit how much driving you do in those circumstances but yes, the car will let you know when there's a problem.

 

[8bit]

I'd have thought you'd want a higher fan speed to improve idle temps, the coolant will only cool down so quickly when there's no air moving over the radiator surely? Where did you get the connectors?

 

[8bit]

Nice one, thanks for that. So those are Merc part numbers? I guess there's still some work to be done to connect the new pump in to the Jaguar wiring?