Thanks, guys. I went for the Stant on a forum member's recommendation. I will have my wife (she is a furloughed contractor--no backpay!!--due to the gov't shutdown) pick the part up from the dealer if she doesn't want to drive me to work every day this week. Haha!

 

OK! I got the new thermostat in and she runs great! There was a screeching sound and a few puffs of smoke under the hood that had me worried for a few seconds at startup, but that went away quickly.

The coolant temperature used to hover around 195-200ºF as reported by my Torque for Android App on hot days (90ºF+). Tonight's drive was done at about 70-75º ambient temperature, and the coolant temp was shown at 205ºF. I thought this was a 183º thermostat! Where do you think the ECU is measuring the coolant temp?

 

Oh, and I forgot to mention. The car is filthy (hasn't been washed in a month) and is covered with pollen and dirt. As I went for my check ride, not one but TWO people in separate incidents said "nice car" as I drove by. What gives?

 

Water temp is measured at the Water Thermo Sensor. Part #17 in the first jpg you showed in this thread. I'll re-read your posts but I don't think your readings are abnormal.

 

Came back to the car this morning and there was a pool of liquid underneath. It could've just been residual coolant that was on the undertray. The system actually seems slightly overfilled. I will get one of those handy turkey basters and remove some coolant .

No CEL, though.

 

Do you know of the correct part #'s you ordered?

I have an 08 XKR and need a new thermostat and probably that gasket. If you could help, greatly appreciated.

Thanks!

 

AJ811788 THERMOSTAT
AJ83525 SEAL-THERMOSTAT

I would recommend replacing both.

CEL has not come back so I'd say the problem is fixed!

 

Thank you very much!

 

I would have stopped at the golf course and let the car rest for 4+ hours.

 

Just FYI, there have been no coolant leaks and no coolant smells, so I'd say the thermostat replacement was a success!

 

If your having problems with the temp warning or fans running more than you usual, you Must check your thermostat and the housing...Up until 2 weeks ago I noticed my fans running and I had purchase a Bluetooth scanning tool, and found my engine temp was getting above 230 degrees, after opening the thermostat housing my thermostat was completely broken and the main housing was cracked in the inside, see attached.. I managed to purchase the whole assembly from Gaudin and put it in this weekend...if you can rebuild a carburetor you can install this assembly. .My Xk only had 49k miles as well. My xk now never passes 198 degrees as of yet, and now runs awesome...It would seem the design is poor and if you have over 40k miles, it will eventually fail..
This is just my two cents..

 

The stant thermostat looks like the one used on 2006 and earlier models. Looks exactly like the one that was in my 97 XK8.

 

I realize I’m about 10 years late to your thread lol, but just ran into the same p0128 issue with my 08 XKR.

Do you recall if the thermostat you replaced was a 4 piece unit that needed assembly? The 4 piece unit appears to be the correct part for the XKR specifically (AJ811788) but just want to confirm before ordering.

Thanks!

 

Ya, the real one some assembly.