1997 XK8 - 85000 miles - 2nd owner, good records. Started over heating (granted, it was 108 here in northern Idaho). After cool down, refilled antifreeze, with no sign of leaking in any hose, seal, etc. Still over heated. Replaced thermostat. Still ... so assume next step is replace water pump, although, no leaking - hoses solid. Temp briefly drops when I run heater - my best thinking is still water pump. Other thoughts?

 

To be honest 42C is pretty hot. It doesn't get much above 30C in the UK. So far thsi year it's not gotten anywhere near 30C even.

 

Usually when the bearing goes so does the seal and it leaks ...not being specific to jags but on some constructions, the impeller comes loose and does not rotate .If you run it without the thermostat and it heats you only have the pump or a blocked radiator ..you could reverse flush it and also check if the fins are blocked.

 

Water pump on early cars is definitely something to check - especially if you don't have history of its replacement.

There are options for new (e.g. AC Delco 252-800, which I used), although see this post from DonB:
https://www.jaguarforums.com/forum/x...7/#post2177569

 

Finally got around to pulling water pump - no impellers left intact - just plastic bits, which I presume are now scattered throughout my engine and radiator - hoping a hard flush will remove most pieces - will look on ebay for a "plastic magnet" - plan to install replacement pump this weekend and hope my overheating problem is resolved.

 

I'd say open up all the choke points, like the thermostat, and the 2 lines to the heater core by the heater valve and pump. It should free up separate areas to flush out. There are also removable drain plugs low on the engine block to help in this effort.

 

Thanks for these suggestions - I'll poke around for them. If I want to "back flush" the radiator with water, which input would I use? "Top" hose port or "bottom" - meaning, the opposite of the normal flow from the water pump?

 

Check the radiator, the transmission cooler is on the left side end tank, which one would assume is the cold side. The hose is more mid-mounted, but counts as the lower radiator hose. This is would be my fresh water input for a flush.

PS: Take this opportunity for a chemical flush as well, this will restore the heat transfer. Get you warmer quicker in the winter, too.

 

But I did have an "oops" moment when I saw the old o-ring and recalled that I didn't put one back on with the new Airflex pump - my research indicated the new pumps magically do not need one (?) - test drive with no leaks and stable temp - thanks for the input.

 

Stable temp is a computer controlled illusion on the temperature gauge. An OBDII monitor or RealGauge will give you early warning for overheating.
See https://www.jaguarforums.com/forum/x...e-gauge-62813/

 

Can the learned and all knowing of the forum tell me if my '03 has a plastic impeller in the water pump? Again I mention I have no issues right now but wish to be prepared. If it is plastic then I will plan on replacing that this winter. Thanks, TM

 

Plastic impellers are not all bad. The early AJ26 pumps had bad impellers, but later models need not be concerned unless they severely overheat, which will probably result in many other other problems like dropped valve seats, blown heat gaskets, warped heads.