Thermostat Problem???

[chris200]

My W204 C200 CDi has a normal running temperature of around 50 on the gauge but when in prolonged stop/start traffic (30 mins or more) it climbs to around 90-100. When normal driving resumes it goes back to the 50 mark. Is this too low? And if so does it suggest a thermostat issue or something else perhaps?

 

[Troon]

It's stuck open. Replace it - not a hard job, not particularly expensive. That engine should run at 90°C all the time once warmed up.

 

[chris200]

It's stuck open. Replace it - not a hard job, not particularly expensive. That engine should run at 90°C all the time once warmed up.

Thank you Troon. I'm no expert on these matters but I suspected it wasn't quite right.

 

[chris200]

New thermostat fitted this morning. Now reading 90c on the gauge. Happy!