W210 E320 CDI thermostat replacement

[IanT]

Two questions in one thread...

I think I'm diagnosing a stuck open thermostat on my new car, while in slow moving traffic, the coolant temperature rises to around 80 degrees C, but when on the open road, it falls to between 50 and 60 degrees. Whenever I've seen this before, it's been a faulty thermostat, is this a fair diagnosis?

Given I need to replace it, what do I need to order? How does the stat come as a replacement part, how much is it and what extra parts need replacing at the same time?

I can only refer to my previous experiences with Vauxhalls, where some came as a whole stat housing, in which the main failure was pitting of the seal cut into the housing itself.

Any help appreciated.

Thanks,

Ian.

 

[ringway]

THIS thread should tell you all you need to know.

Optimum operating temp is 87 but anywhere between 80-90 is okay.

 

[IanT]

Thanks... is there an o-ring that's ordered separately?

Ian.

 

[panason1c]

The stat comes complete with its housing and even includes the temp sender unit!, it also includes 0 ring seal........cost circa £50, easy to fit.

 

[IanT]

Cheers, I'll head down to the stealers on Friday then. It'll only get worse as the colder weather comes around, so it's better to fix it now, while I can still feel my fingers.

Ian.