Its official, i am now one of the initiated. After 4000 miles I got my first check engine light, my code reader identified it as p0128 which appears to be a defect on the later thermostats leaving them partially open. I have already ordered the new thermostat, but i had a question for those that have gone before me. I understand that the later model xk8s have a different thermostat setup, so does this mean that i will still need the bent wrench to reach the bottom bolts or will i be able to remove them without purchasing or fabricating a special tool? I was also wondering how difficult the water pump replacement is on the later models and if you guys think it is even necessary (are the later models still prone to failure?) since i will be flushing the system i figured i may need to do that now rather than later. Thanks guys!

 

I just changed the late style thermostat that comes in two pieces and wow that was the most ridiculous set up i have ever seen. I dont know if there is a special tool for removing the old compressed thermostat but it was terribly difficult to get out, i practically broke my thumbs, the housing is plastic so you can't really get tough with it. I don't know if they sell the housing with the thermostat pre-installed, but if they do i highly recommend anybody doing this buy that instead of the thermostat separate. Now that i have installed the new one i cant help but worry that its's not aligned right, because once you compress it the main (large spring) is not completely straight, maybe i'm just being paranoid. Anyways can't believe something as simple as a thermostat was turned into such a ridiculous pain.

 

I found a trick to installing and taking out the multiple-piece thermostat (for the later models), using a 1" open spanner wrench to do the work, it was a breeze after that.

to the OP, I've never done a water pump replacement, but plenty around here have, and will give you some confidence on that issue soon.

The thermostat housing should also be replaced, if it isn't already, to the metal one...$80 online for the entire kit (including new t-stat). That is easy peasy.

 

I just replaced the thermostat and housing in my wife's 2005 XJ8 and it was a bit difficult and time consuming. The main problem results from the fact that the air intake ducting and throttle etc is on the front of the intake manifold, and you need to take all that stuff off. I don't know about the XK8, but I was able to buy the themostat and housing preassembled for about $80. Having read the perils of guys replacing just thermosats, I figured that preassembled was the way to go. Now I know it's the ONLY way to go. I can hardly wait to do it on the XK8, especially since the bonnet hinges at the front and probably restricts the access somewhat. Oh well, like my wife says: "That's the price you pay for being a Sport."

Cheers,

 

Wait so there is an aluminium housing replacement for the later models? I thought that the metal replacements were only for the one piece thermostat setup. Man i wish i knew about that in advance, for only 80 dollars i could have got an already assembled metal housing, i paid half that for just the t-stat. Where did you guys buy the metal housing kit? Thanks

 

sorry, my mistake, thought you had an earlier car waterloo. No, there's only the plastic available, I had to replace mine after it started a leak last year from the center neck...goofy design.