Heres a brief overview on my 5.0 liter thermostat replacement. I know its been covered many times in this forum but maybe some of this will help someone.

2013 xkr with 65,000 miles. I discovered a leak and pressure tested the system and found where it was leaking from. Luckily, I caught this in my driveway. Once the driver's side intake plenum is removed you can see the thermostat. The 2 plastic hoses going to the supercharger can be disconnected and zip tied out of the way. The lower hose clamps were a pain to remove. There’s about 6 of them total. I used a special hose clamp plier kit I bought online for $14 that made it a lot easier. Forget about using pliers to remove them.

heres the view of the thermo after removing the intake plenum

The part on the right is manufactured by several aftermarket companies and is readily available all the way from a cheap Chinese brand for $30 to $120 for the factory part. The fact that so many companies make these proves that these are failing quite often. I bought a mid-level one made by Motorad for $60. The part on the left is part 8W83-6A968 and is discontinued and not available anywhere brand new. I really wanted to replace it since I had it out, but I had no choice but to reuse it. I closely examined it for cracks. The 2 halves are connected using a wire type spring locking mechanism.


The weakest point of the entire cooling system has to be this O-ring that is sandwiched here where the arrow is pointing. Heat cycles will cause it to harden and flatten and result in sudden coolant loss. Check out how discolored the pipe fitting is. The mating flange had become warped as well and I could fit a .005” feeler gage around most of it. There are factory part stampings on it so it could have been an original.


Here is the hardened O-ring. The guts of it have been removed..Too bad no aftermarket companies make this housing out of aluminum like they do for the cross over pipe…



The hose/pipe assembly that connects to the top of it was swollen and was available, so I purchased it for $52 and it is made by Gates. Put it all back together and pressure tested it and no leaks. Overall, I spent 6 hours spread over a weeks’ time. If I had to do it again I could do it in 3 hours. Total price for the hose, thermostat and coolant was $130. If I would have brought this to a local indy shop it would have been near $1000 here in So Cal.

 

Well done. Did you happen to check the other plastic coolant pipe/hoses while you were in there? Are you the original owner? 6 months ago at 14,000 miles, I had every plastic coolant/line/hose replaced that I could think of all at one time. Removing one part can disturb another and if original all are becoming brittle from heat/cooling cycles. The thermostat was of course one of them, but doing everything made sense at the time. Now I have at least another 6 or so years before worrying about it again. Our cooling system is the weakest link in XK ownership.

 

There was an endless amount of other hoses that I would have and should have replaced. All it took was one hose that was tough to source and i had to wait 2-3 weeks to get it and finish this project. My garage space is limited and I needed this car back in driving condition a soon as I could.