+1 distilled water only!

 

Ford has been changing some of their impellers to metal, and are generally recommending HOAT instead with them.

 

Cool, thanks for the heads up on this... My original pump with plastic impeller didn't fair too well finding bits in the plastic thermostat housing.

I can't remember if the impeller is aluminum (which is possible) or metal... It's been a while and I don't want to jinx myself as my cooling system is totally behaving!

 

Just as a point of reference, this is the true Jaguar part and gasket. No sealant is required on this gasket.

 

And for comparison to the OE Jaguar pump in David's photo, here's the Airtex AW4124 pump. Note the similarity in the impellers:

 

Interesting discussion. I am using Dex-Cool and had not heard about it causing steel corrosion before.

When my 06SV8 was overheating last September, Some here suggested the cause might be the water pump's plastic impeller slipping and that replacing the water pump with one with a metal impeller would cure it. I did replace the water pump with one ordered from the local O'Reillys Auto Parts store.

The first $45 MasterPro 58-612 pump did not look like the one I had removed, did not include a gasket, and had two fewer bolt holes than the old pump so they decided someone had put the wrong pump in the right box and ordered another one. When it came in they said it cost $85, but they would knock it down to $65 because of the first mix-up. This pump had a black plastic impeller and on the box it said: “The OE manufacturer has changed the housing design on this water pump.”and that this is the “new design” and may be different from the “old design” pump you removed which used “a plastic insert with an O-ring and a gasket” and “the new housing is all metal with a gasket.” It came with a plain paper gasket and I used #2 non-hardening gasket cement on both sides of the gasket and installed it with anti-seize on the four pump bolts.

The impeller in the old pump (also black plastic if I remember correctly) did not slip and I determined that my overheat problem was caused by gradual coolant loss from a leak. The leak may have been at the back of the mechanical pump because I did notice coolant there when I removed it so replacing it may have helped, but I also worked on the IC pump and replaced brushes in the auxiliary pump at the same time so the leak might have been elsewhere. In any case all has been well with no leaks since September 2016 and no overheating.

 

Early X100s and X308s had black Nylon 66 impellers, which were known to deteriorate, and were subsequently revised to black polyphenyl sulfide (PPS). Early S-Types had the black PPS impellers but those were subsequently changed to white poly phenyl sulfide. Jaguar specified that pumps with black Nylon 66 impellers should be replaced but that those with black PPS impellers did not need to be replaced. Orange OAT Extended Life Coolant (XLC) was specified for all S-Types and all X350s. Here are a couple of relevant TSBs - I think there were others:

TSB 303-60 Coolant Pumps - Identifying Impeller Materials - Pump Replacement Guidelines

TSB S100-06 Extended Life Coolant (XLC) - Identification - Precautions

Cheers,

Don