diesel thermostats
 

Got a hold of a couple of old thermostats from a couple of blown eco diesels
Both appeared to have been after market thermostat units, both marked as 88c.
One opened smack on 88c and the other opened up at 66c.
Wonder if there is that sort of temp variance in new thermostats?

That is why you should always check the opening temperature before fitting!

Very true, ill bet not many mechanics bother checking.
I was looking on the net at some after market ones for the vm diesel and
zooming in some of the cheapies there stamped with 98c instead of 88c.
Probably why there cheap.
Was looking around to see it anyone sold the elements as they just twist out of the housing as the oem jeep housing (italian made) have a slightly heavier housing construction than aftermarket ones and alot of brands use similar type elements but no one seems sell the elements seperately.
If you could find a quality element be alot cheaper.
Dayco want $250 ish and jeep want $400 ish , after market ones start at $30!!!

No, the variation should only be a couple of degrees ................

Since these thermostats are 88 deg C jobs, its best to test opening temp using a coolant mix the same as the engine, especially if you want to note the actual temp it starts to open and the temp by which it is fully open, at fully open the water may around boiling point, not wise, so using coolant pushes that temp further away, a thermostat in boiling liquid has a very good chance of damage..
. Hanging the thermostat with a bit of string under the valve easily shows the start of the opening temp as the unit will drop off the string.... as the coolant gets hotter the valve will continue to open to around 20mm or more.

its also just as important when its cooled down the valve actually closes evenly......

I had a new "genuine" thermostat fitted to mine by a very well known and trusted Jeep specialist workshop...it had 98c stamped on it, and that I was told was the normal standard opening temp for the VM.
The engine had been operating far too hot for my liking running at around 99c to 100c. Towing was ridiculous with temps hovering around 110c and above.

My previous (RIP) WK2 ran at around 88c - 90c all the time rising to 94c - 96c when towing.
I took the thermostat out of the old Jeep and put it in my new one and temps are back where they should be imo. Coolant 94c, oil 104c while towing...
All 3 thermostats I have show 98c as opening temp stamped on them...all open at different temps.
The Jeep guy reckons the one I have must have a "weak" spring in it...all good as far as I am concerned...

Mines 88c, etched in the side, sa gooda talian jobo..................eh!!!!

the 3 i have, all have 88c stamped on them, including the factory one “made in Italia”.
As nentioned one of the used afternarket ones opens at 66c but stamped as 88c.
I believe the Dayco thermostat is 88c and seem pretty decent quality but not cheap.