I need to install a new thermostat in my XJS 4.0. Since I removed the old one some time ago, I can't quite remember the correct installation order for the gasket, thermostat, and O-ring. To my surprise, I haven't been able to find any diagrams, not even in the repair manual.

I believe that the O-ring goes into the rear of the thermostat housing first, then the thermostat with the vent hole facing upwards, then the gasket, and finally the housing cover (to which the rubber hose is connected).

Can anyone confirm if this is correct?

Thanks and best regards,
Martin

PS: The new thermostat didn't come with an O-ring, but with a plastic ring that fits onto the edge of the thermostat head and then rests on both sides. Perhaps it's not intended for Jaguar?

 

Thanks for your reply. You are so very right…
This is weird, because the broken thermostat I removed had the gasket *and* the O-ring mounted.
When I first mounted the new thermostat (with gasket and O-ring), everything went well, no leaking. It was only after that when I learned that the little hole with the pivotting pin should face upwards. So I opened the housing again, and when closing, the tap actually broke (should have asked you before :-/).
Then I ordered a new tap which was announced by the seller as EBC10345 (which would mean the latest version of this part, probabely for the AJ16 (?). The part I received, however, was EAC8209, which is the former version (for AJ6?) according to https://parts.jaguarlandroverclassic...tat-cover.html
Its slightly different and seems to be moulded to take the O-ring, see photo.
Is there anything against using it with my AJ16 engine?
Thanks & best regards
Martin

 

Thank you so much, Grant. I‘ve ordered a tube of RTV.

 

Good morning,
Resuming for further generations (correct me if I’m wrong): EBC10345 is the newer version, used for (later?) AJ16 engines. It takes the gasket, and when you try to mount it with the O-ring (which comes in many cases with the new thermostat), it might break like mine did.
EBC10345 superseeds EAC8209, which was used for AJ6 engines (and perhaps for early AJ16 engines). It takes the O-ring.
I‘ve mounted a new EAC8209 instead of the broken EBC10345, with O-ring and RTV. For the moment it seems to work, no leaking.
Thanks again
Martin

 

YES,

I got it A about Face, and Vee has pointed that out. I have asked Norri to delete my posts related to that.

Apologies to all for the screw up.