274 Engine Problem

[phil barker]

Problem with my E250
When the engine is warm and running normal the temperature gauge rises to 120 and goes into the red and then the Coolant-Stop-Switch Off Engine message appears.
Sometimes the message goes off and the gauge needle seems to bounce up and down between normal and 120
BUT the engine is not overheating as the message says, it is normal and runs fine. Although I have noticed a slight drop in acceleration power.
A wiring loom and the thermostat have been replaced but the problem persists.
Can anybody suggest what the cause might be?
The car is with M-B at the moment searching for a solution

 

[John Laidlaw]

250 Diesel Phil?

 

[LostKiwi]

Temperature sender?

 

[phil barker]

Its a petrol engine E250 Night Edition 211bhp

Star says sensors all ok

 

[phil barker]

Just an update
New Temperature Sender and Thermostat fitted
All seems to be good now back on the road no problems over the weekend

 

[ernieh]

Was the thermostat replacement mentioned in Post #1 duff, then, or was it an aftermarket one?

Ernie

 

[Steve@Avantgarde]

There is a software update for this and a technical bulletin from MB which explicitly says not to replace the coolant thermostat. Its a faulty correlation from the A/C system and coolant temperature sensor that causes the problem. Quite common with the 274 engine.

 

[Flyinspanner]

If there was a TB which explicitly said don’t change thermostat, and they did, I hope you don’t have to pay for it - they should RTFM

 

[phil barker]

Thanks for all your responses
The car was with M-B as there is still 5 months warranty remaining so no cost to me
As for the bulletin ….well I wouldn't know only going off what they told me.