I just followed MrTexasDan's excellent guide on how to do a thermostat replacement on an XK8/XKR - you can find the link to it in the FAQ sticky at the top of the XK8/XKR thread.

It looks like there were a few updates for the 2006 model year and I am assuming those came in with the 4.2L engine and/or ZF transmission in the 2003 model year. What I found:

Accessing the radiator drain plug: my car seems to have an extra tube in the way - not seen in MrTexasDan's pictures - that complicates access to the radiator drain plug. Although I did manage to locate the screwdriver on the drain plug by feel once, it's generally going to be a lot less effort to jack up the car each time you need to access the plug. Remember you will need to lower the car for the radiator to drain effectively, so there is a lot of up and down to do if you are going to do a flush.

Thermostat housing bolts: On my XKR, the thermostat housing was held on by T-Star screws, not 8mm bolts on earlier models. I used a T-30 bit in a very tiny ratchet to get the bottom one off (Harbor Freight Right Angle Screwdriver - catalog number 92630 - a great tool for 5 bucks!- but you will need to get the T-30 bit separately)

Capacity: Although the rated capacity is 11.5L of coolant, I could not drain more than 5L.

Jacking: My car has a plastic skid plate between the bumper and the front crossmember that was probably not there pre-2003. Per advice in other threads, that front crossmember is the correct jacking point. I was able to jack from the front crossmember even with the skid plate in place and it does not appear to have caused any harm.

Other stuff that would apply to all models:

The black reservoir makes the coolant look dirty, even when it isn't. My coolant looked filthy when looking at it through the filler cap, but when I drained it out, it looked brand new. I have only owned the car for 6 months so I don't know how new (or otherwise) it might actually be.

I used distilled water for flushing and for both filling operations. Given that I spent $65 for 5L of geniune Jaguar coolant, saving $1 on a gallon of distilled water didn't seem to make sense. I am really happy with that decision knowing that one can only empty half the coolant per draining. Although other discussion threads talk about changing the coolant type, I think using a chemical flush and trying to change coolant types is just risky given the difficulty in fully draining the cooling system.

Dan's magic tool for opening the intercooler plug is an excellent idea. I happened to have a bolt of the correct size in my garage, and it had a large spring washer threaded between two nuts on it already, so I just tightened it up as it was. The washer stopped the wrench from slipping off a few times and is a useful addition.

This was my first time jacking up my XKR. The front end is HEAVY. I have always jacked up cars with a piece of wood between the jack and the car to spread the load. As I was jacking up the XKR for the first time, it split a block of 2-by-4 like it was a twig - and I didn't even have the wheels off the ground yet. MrTexasDan said it in his instructions too - do not get underneath your car unless it is properly supported - even just for a second to get a look at that radiator drain plug! Never rely on the jack alone if any part of your body is between the car and the ground.

Once again, hats off to MrTexasDan who wrote the original guide, to whom I definitely owe a beer!

 

I miss MrTexasDan, he hasn't been around in a long time. Last logon - 3/23/2011

He had many good DIY procedures that he was working on for us. A great resource. I'm pleased his efforts placed on his earlier work is still being put to good use. I used it also on my 2003, noting the same minor differences as you did.