I read somewhere that it is a good idea to replace the thermostat at 50,000 miles.

What are are your thoughts on replacing the whole plastic unit, or just the thermostat? It looks like I may have to remove the intake manifold to get the whole plastic unit out, the housing comes apart where the yellow clip is, is it a bad idea to leave the base screwed in and just remove/replacepart of the plastic housing?

 

I can't see your photo(don't ask).

1 It's a good idea to replace the whole plastic unit because:

2 The plastic can degrade inside and partially block the flow of coolant.

It's not obvious how the stat fits in the housing.

Wait for a member who has had to do this job to comment.

I am just repeating what I have learned on this forum.

 

Two years ago I changed the thermostat and housing on my 2007 xj8, however i left the part bolted to the top of the engine rather than monkey around with the throttle body, If you remove the yellow part in the photograph you can separate the bottom part of the housing, I put the new seal on the old part that was still attached to the engine, I hope you find this info helpful,
regards
Dave
2007 xj8,

 

I changed just the thermostat one year ago (torn seal). Car was fine until last month when it started increasing temp a degree or two when below 30mph. Changed the housing and it fixed the temp rise and the car now runs 4 degrees cooler.
Changing the assembly is a bit of pain but I'd recommend you do it as it will potentially save you having to go back in to do the whole thing.

 

Did you have to remove the intake manifold to completely remove the thermostat housing?

 

No, not at all. I used this thread to do it: https://www.jaguarforums.com/forum/x...3-tips-114486/