1st time posting and searched. I have an 08 E350, my 1st Merc and my 2nd German car. Recently replaced my thermostat and this morning the temperature went well beyond 80C. Outside temp was in the low 40’s. Reason for thermostat change is a P0128 code. Is this normal? Before the replacement, temperature only rises to just above 80C.
Thanks!

 

I'd say normal. The old thermostat likely allowed more uncontrolled coolant flow, thus keeping the temperature lower. The new thermostat doesn't suffer that issue.
Worried? Find a good long uphill run and flog it while watching the temperature gauge closeley.

 

Appreciate for the response! I’ll definitely try that long uphill, there’s one close by. As a good measure, how do you bleed the air out anyway? Do I need to bleed it out in the first place? In my VW, there’s a pin hole that has to be exposed when bleeding. I don’t see any in the merc and no mention in the forums.
Thanks again!

 

Just keep an eye on the overflow tank. Fill as needed or as the car tells you the coolant level is low. I typically have had to top things off about 3 times (heat cycles) until the system is fully burped.

 

thanks! Appreciate it!

 

I have the same temp in mine. The thermostat has been changed for 5months now, and with the warmer weather my radiator fan starts running on high speed. This happens maybe 10 or so miles after getting up to temp. sometimes not stopping if driving in the city. I see no change to the temp indicator on dash and car has been driving fine. But the fan will run at top speed like it’s not cooling. Also not really using the ac yet but that haven’t changed the temp either on the few occasions I have. Any suggestions on what to do? Or cause?