dimgia

Hi
I have just bought a w203 coupe with m271.940 engine.
When i'm in the town my temp gauge shows the temp a little bit over 80c. When I'm in highway cruising falls where the image shows, maybe a little bit lower. I thing this is not right. Maybe a stuck open thermostat? What's your thoughts?

insame1

I dont think that is correct either. How long does it take to get to 80?

Russell Ormerod

Looks a bit low, I would replace the thermostat

dimgia

I think it takes about 10 minutes. I will check it today for sure. The 10m minutes is when I start the car and ride it. I will check the time when only idle
I have bought thermostat and coolant but before replace it I wanted another opinion.

insame1

I do believe you are on the right track. I just have not seen this issue before on a MB. If it takes a long time to bring to temp on startup under normal temperatures then I would agree that it is the thermostat. If you already bought one you might as well put it in.

slammer111

The thermostat may be bad, but when mine failed, the car threw a CEL on top of indicating a temperature around 70C like yours. Just keep an eye on it. I think the only things affected by a low operating temperature are emissions and fuel efficiency. It won't kill your car.

The thermostat is easy enough to replace. 2 bolts in the front of the engine. Be sure to have a jug of coolant handy as 2L or so will gush out.

I agree with the others that the car normally warms up to 85-90C during normal operation.

dimgia

Hi guys
As expected the thermostat was stuck open.The thermostat I bought was a mahle but inside was a wahler as the genuine mercedes. Now it goes 80c quickly. Thanks for help