Amazing how that broken off piece will just sit there at the water pump. I removed my water pump and saw the piece, but reinstalled my old water pump even though I'd bought a new one. I keep that one in the trunk on long trips along with a (used) serpentine belt.

 

Been having overheating problems with my 2006 XK. I took the thermostat cover off only to find that one of the retaining lugs had sheared causing the thermostat to go "wobbly". Fitted an new cover only to find the car was still overheating and the fan running most of the time.

Having read this thread I have discovered that the housing has exactly the same problem with the section of housing sheared off.

Thank goodness for this thread as I was starting to scratch my head as to what the problem was.

 

How common are these thermostat housing failures? Does the 5.0 engines have the same exact plastic housing? Wouldn't mileage and age be a factor as well considering we are talking about plastic?

 

My car is 8 years old which I have had from new and done 112K.

Don't know if the same parts are used on the 5 litre but clearly the plastic parts are more prone to failure with extremes of heat.

Surprisingly the whole unit including new thermostat was much cheaper than I expected at £85.

 

Just a wee bit of advice for anybody with an XKR 2007, recently arrived home after a 40 min drive , last few miles heard some pinking from the engine , shut down on driveway with steam coming from engine bay , no warning lights on at all, just the engine management light on at shutdown , reservoir empty , split hose found underneath the supercharger at rear, just hope I have not done to much damage , car started normally once cool next day , no lights , car now in dealer having pipe replaced , any one have any thoughts as to what might be worth looking at .

 

, any one have any thoughts as to what might be worth looking at ...............YES, the bottom of the expansion tank has a nipple a hose goes to. My engine bay looked pristine, but when I came back to TX from SD a couple of years ago, the next morning I noticed water under my car. A small puddle. I found the bottom plastic nipple on the expansion tank was crumble cake at the hose that attaches to it. Had to replace the tank with a new one. Heat broke down that nipple on the tank.

Oh, yeah. That short hose cost a BUNDLE. It's but maybe six inches long but has two different diameters on each end.

I traded the XK for a CL550 and no longer have a Jag and rarely visit here.

 

Hailers, was your break in part 14 or 15?

 

From his picture, I'd say it was part #15. When I did mine, I just bought the whole thing, part #11, and replaced all except the un-numbered part, and part #19 on the right side of the diagram, which is attached to the engine. Would have had to remove more stuff to get to those bolts.

 

Ditto. The plastic T stat assy is garbage. There are little tabs that are required to hold the spring pressure and they break off / erode away and end up in the water pump breaking the fins. The aluminum //R design is much better. I went through this on the kids Lincoln LS which shares these parts.

 

Yep, Mine looks EXACTLY like your broken piece also. Pictures in my thread. I now have to find the other part and receive quickly!

 

On mine the tab in part 14 broke allowing the thermostat to move from position slightly This then caused part of the inside of of part 15 to break. The damage in 15 was very hard to see at first. In the end I replaced both 14 and 15 and all was good.

 

Yes, it is necessary to remove the intake manifold (which I did last year) to replace the "un-numbered part". The spout of that part which mates with the rest of the outlet pipe had a bit of plastic break off where the O-ring, part #16 is seated. That motivated me to remove the intake manifold so that I could do a complete job.

 

Intake manifold??
Throttle body and Elbow leading to the intake manifold is all you'll need to remove to gain access.

 

Is a new throttle body gasket going to be needed?

 

Should be molded O ring material so no. A dollop of grease will help them seal.

 

My 2007 had a metal gasket, so I replaced it when I removed the throttle body.

I removed the intake manifold because I wanted to replace the hose that connects from the engine valley (behind the coolant pump) to the throttle body, a common failure point. My recollection is that it would be very difficult to remove the "unnumbered part" with the manifold installed.