Poor heater X100 2005.
 

Starts off warm, then fades to poor. Recent thermostat. Any thoughts? Thanks.

It'll be the electric pump. Not at all easy to get to! Have a look at this: https://www.jaguarforums.com/forum/x...41/#post752880

I did see a post where someone left the original, failed pump in place, and just added another aux pump at a more accessible spot.

Great advice - again. Many thanks, Dave.

I am sure you can find a diagram online, our heater setup involves a loop with a pump and an electrically-controlled valve. It all is in a cramped area, not super fun to reach/work with.

Before getting in too deep, check the basics.

• Check the overflow tank and make sure it is full. Maybe there is air in the system. Make sure it is all topped-off
• Unplug the heater valve. It is on the firewall and somewhat easily reachable. It defaults full open. You should have TONS of heat
• Execute a heater core cleaning. Use radiator flush solution e.g. Prestone. The lines to the core are accessible with hose pliers. You can plumb a garden hose setup for (back) flushing. I have done this before and it made a world of difference.
• Check the wiring diagram and measure the resistance of the heater pump. "Infinity" means open circuit, a common problem, indicating the graphite brushes have worn down. This can be repaired. If the pump is dead, there is less/no flow of hot water to the heater core and the heating air is lukewarm at best.

Best of luck, keep us posted.

Thanks fmertz, very thorough.
Other than the simple checks, it’s one for the winter lay up if the full strip down is required.

Anyone discover a link for running a second aux pump in tandem, as previously mentioned? I ran out of key word ideas and drew a blank!

This isn't the thread I'd seen recently, but have a look at post 6 here: https://www.jaguarforums.com/forum/x...orking-152373/

Thanks for link. Think i’ll do the job properly.