Here is a pic of my thermostat At the end that cannot be seen (where the thermostat closes) is a neoprene/rubber/vinyl whatever it is made of that's torn causing P0128 code (Coolant Temperature Below Thermostat Regulating Temperature.) The gasket material is causing the thermostat to remain partially open.
The Stant #14748 thermostat I ordered it is not even close to a replacement part although their Web Page said it does fit my 2007 S-Type R.

Is it possible to find the rubber/vinyl/neoprene seal or the complete mechanical thermostat replacement for the one installed in my 2007 S-Type R? Or am I going to have to get the aluminum housing with the thermostat already in it?

 

Found what I need here

https://www.jaguarmerriamparts.com/p...iagram=4731174

[ 19 ] COOLING SYSTEM / COOLING / RADIATOR & COMPONENTS / Thermostat
Part Number: AJ811788

thermostat 4.2 LITER, W/SUPERCHARGER
MSRP Core ? Online Price
$50.50 $0.00 $37.72

 

 

So I put the smaller spring seen inside the green outline on the wrong side of the thermostat. It is should to be inside the larger spring and goes inside the brass looking cup with the small end up. The incorrect installation of the thermostat caused me to replace the Dual Climate Control Valve and the Auxiliary Coolant Pump (circulates coolant through heater core). Still no heat with the new parts. Back to the thermostat and realize that I had installed it incorrectly. Installed the thermostat correctly and now the HVAC is working as it should. Left the new DCCV and Auxiliary pump in place and have a spare for future because both are in fine used condition.

 

Glad you figured it out. There have been several reports here over the years of folks assembling their new thermostats incorrectly. Sorry it cost you a couple hundred bucks in new parts that you didn't need....

 

Consider it preventive maintenance. It was only a matter of time before your 9yr old DCCV failed anyway.

 

Old thread I know, but I ordered a thermostat from Ebay that supposedly was a guaranteed fit replacement part, and it is also not even close. The rubber o-ring in particular is entirely different, and does not lead to a good seal. the leak started almost immediately.

 

AJ811788

AJ83525 aka 4362513 o-ring


dealer only. if you try to cheap out you will need to **** around with zipties or a vice to get it installed

 

Here is the one that fit perfectly. Mahle replacement for the VW group vehicle range, fits Audi A4 etc.
Miles cheaper than the Jaguar one at the time.
Fleabay is awash with incorrect parts and part numbers. Only buy there if buying genuine parts.

Audi A4 is the perfect fit. Also I think the same one is on the Passat B5 Transporter. I think part number is T4 078121113C

 

this about the lego thermostat in the x206 vvt engine