Hi All

I had the misfortune to have my thermostat housing break in two, resulting in coolant everywhere and a steamy situation all round. The AA were kind enough to drop my car home and tell me it was a common fault where the union has broken in two as it was made of plastic and gets brittle over time.

So here we are. Is this a job a reasonably skilled home mechanic can do with some instructions or is it a bigger job than that?

If so, can anyone recommend any videos and can someone please confirm this is the part I need?

https://www.ebay.co.uk/itm/313303702...101949.m162918

I've had a short tinker and this part will need to come out to get access to the broken housing. If someone could please point me in the right direction or instructions for this I would be grateful.

Many thanks in advance and apologies for the multiple requests for help

 

OK, with a little help from a tutorial video I have gotten this far.

I have three questions.

1. These look incredibly 'gunky' - do I need to clean them or is that normal fora 117k car?
2. I can't even shift this and don't want to risk breaking anything further - brute strength or is there a technique?
3. Again, this bit won't slip off - any tips without breaking anything
   
   ?

Then it's just ordering the part, putting it back together and refilling it - avoiding airlocks (I will ask more about this at the time, I'm sure!)

 

This will help......

 

Great guide and super clear - thank you John!

Got one of these on the way and soon be up and running again

 

Hi all,

Hoping someone can offer a bit of guidance…

I’ve just finished replacing the (cracked) thermostat housing on my XF – all went smoothly, and the engine starts and runs fine. However, I now have two warnings on the dash:

• DSC Not Available
  
• Restricted Performance
  

I’ve not driven the car yet – just started it up to check everything was working. I suspect these warnings were triggered because I (accidentally) started the car mid-repair, while some sensors and pipework were still disconnected.

I know this kind of fault often clears with a proper drive or a reset – but here’s the issue:

I have an iCarsoft 2.0, which previously caused problems on this car (bricked it until I did a full battery reset), so I’m very wary about using it again just to clear codes.

Has anyone else seen this combo of warnings after intake/coolant work? Did it clear itself after a short drive, or will it definitely need a diagnostic reset?

And if anyone can recommend a safe code reader for JLR vehicles, I’d love to hear it!

Thanks in advance for any advice.

 

Update – Job Done (Thermostat Housing Replacement + DSC/Restricted Performance)



Quick update for those following along — and thanks again to everyone who offered advice!



✅ Thermostat housing successfully replaced (went with an aluminium version)
✅ Coolant topped up and seems to be holding well after idling for 10+ minutes
✅ Hard reset via battery disconnect cleared the “DSC Not Available” and “Restricted Performance” messages — no OBD tool needed



I haven’t taken it for a proper drive yet, but everything’s looking good so far.



Only slight thing I’ve noticed is the exhaust looks a bit “whiter” than usual, but I suspect that’s just condensation or me being a bit paranoid after working on the cooling system. No super sweet smell, no misfires, and coolant level looks stable for now – so I’ll keep an eye on it over the next few runs.



Thanks again to everyone on here – really appreciate the help. (And frankly, the forum’s been far more helpful than some of the tools I’ve paid for &#128517