What’s going on guys got this weird overheating problem in my 2011 Mercedes Benz E350. The other day I worked all day and at the end of my shift got back in my car was driving down the highway at 80 with the ac on . All of a sudden my temperature gage started rising, almost to 120 I pulled over shut the car off pop the hood, and nothing was leaking and the fans were on. Got back in the car put the heat on the needle instantly came down back to normal, and I drove the rest of the way home. Then two days later I went for a drive with no heat or ac and my needle started rising again sure enough I put my heat on and the needle came back down to normal. I was able to drive the whole way home without the heat I have no idea what can cause this. I do not think it’s a thermostat because I was able to drive the whole way home without the heat so obviously it was circulating coolant and I know the fans are working

 

Checking the coolant level would be a good start in troubleshooting.

 

checked that it was fine hooked up my scanner got no codes related to any sensors. It is very strange to me.

 

Sounds like thermostat is stuck closed.

 

Drive with scanner for temperature checking.
Dash gauge is dummy and will not move till temp will go high.

 

When you're ready, use a scanner to diagnose the ECU sensor.

Before then... visually inspect connector for poor connections where coolant pressure escaped through pins.

Take this opportunity to inspect for minor leaks in addition to cooling circuit preventive maintenance.

 

definitely interesting the car technically never overheated. I didn’t let it get hot enough temperature light never came on very strange, though I wonder what’s making that needle jump up

 

If you read how it works, up to 115C engine temperature the dash will show 90C.
So in case engine keeps warming up, when the engine passes 120C, the needle will move from 90 to 120, what can be within couple of seconds.
That's why it is called dummy.
Driving with a scanner showing actual temperature will allow you to see if thermostat is stuck.
The engine in normal operation should come to 80C pretty fast and that is when thermostat starts to open, so depends on the engine it might go a bit higher or not, but at slower rate
But when your engine goes above 100C pretty fast, that indicate bad thermostat.

 

Ok ya cuz the needle always stays at 90 then boom all of a sudden shot up to 120 right under the red not in the red pulled over blasted the heat the needle came down and then everything back to normal drove a whole hour with no heat on and the needle stood normal

 

Thermostats on these cars will throw a CEL if it is malfunctioning and then they generally fail in the open position for safety. Not sure what is going on with your car. Maybe a dodgy sensor.

 

It might not even be the thermostat, but the heater at the thermostat.
I never yet scoped the signal to this heater yet, but since our engine is design to RUN HOT like 100 C yes, 100C and when in cool weather ( my region at 22C ) or rain,
engine computer knew cooling power abundant, it often allow coolant to run to 105C.
I seen so often my car goes to 105 and 108C without being pushed hard, but cooler air was available rainining or when I climb to higher altitude.

The heater is to melt the wax at the thermostat to open.
Since there is no way to cool the wax, that means our thermostat wax melting point is not the typical 85C like the older generation car, it must be at least 100C I think.

I been wanting to test this 100C wax theory of mine.

 

Hi RichieBoy, I am having the same exact issue with my 2011 E350. Wanted to see if you had any update on yours?