Thermostat replacement

[Michael224]

Hi everyone
I have 2012, c180, M274 engine ( very low milage)
i have recently noticed that the car won't reach operating temperature as fast as before and on the fast drives on the motorway for example, the temperature even drops down a fraction as the cold weather blowing through the radiator i assume.
On a few short dives i had, it never over heated and after a while driving on a low steady drives it does warm up to the operating temperature which makes me assume that the thermostat is stock half open.
No noise , no rattling and no check engine light yet ,
Anyone has any idea ?

 

[tony gee]

sounds right to me, if you are bombing down the motorway and in cold weather the temp will drop slightly, but at low speeds round the town it will reach normal temp,
if you are stuck in a traffic jam and the temp starts getting to high, if you raise the rev's slightly the temp will drop to normal.

 

[SpikyMikey]

Could just be due to the colder ambient temperatures currently, but keep an eye on it as thermostats can play up on the M274. It's a bit of a PITA to change as well.

 

[Michael224]

Could just be due to the colder ambient temperatures currently, but keep an eye on it as thermostats can play up on the M274. It's a bit of a PITA to change as well.

Thanks for the message
I really hope so , but shouldn't it go back to normal after the system gets warm enough?
Do you know of its exact location or even better a how to replace video by any chance?

 

[SpikyMikey]

Thanks for the message
I really hope so , but shouldn't it go back to normal after the system gets warm enough?
Do you know of its exact location or even better a how to replace video by any chance?

I chickened out and got my trusted Indie to do mine; unfortunately it's not just a simple drop-in wax capsule 'stat but far more complex with a bit of electrickery thrown in.
This video gives you some idea!

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[markjay]

A failed thermostat is unfortunately a common fault on the M274 engine.

The thermostat on this engine comes as a complete unit, including the housing, and it contains an electric heater element plus some electronics, which makes it more expensive than traditional simple thermostats.

Additionally, the thermostat is located under the engine, which requires some dismantling to get to it, not to mention draining and refilling the cooling system (though the old coolant can be collected and re-used, in spite of MB saying that new coolant must be used).

You can expect to pay around £300 parts and labour at an independent specialist, or double that at a dealer.

BTW, if you have access to a code scanner that can read MB codes, try reading the codes: the engine may (though not always) log a fault 'P012800 The coolant temperature is below the coolant thermostat specified temperature'.

See also:

https://static.nhtsa.gov/odi/tsbs/2020/MC-10179907-9999.pdf

 

[Michael224]

I chickened out and got my trusted Indie to do mine; unfortunately it's not just a simple drop-in wax capsule 'stat but far more complex with a bit of electrickery thrown in.
This video gives you some idea!

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Thank you
I have seen this and a few others but none has the exact layout as mine , different parts and stuff ,,,

 

[Michael224]

A failed thermostat is unfortunately a common fault on the M274 engine.

The thermostat on this engine comes as a complete unit, including the housing, and it contains an electric heater element plus some electronics, which makes it more expensive than traditional simple thermostats.

Additionally, the thermostat is located under the engine, which requires some dismantling to get to it, not to mention draining and refilling the cooling system (though the old coolant can be collected and re-used, in spite of MB saying that new coolant must be used).

You can expect to pay around £300 parts and labour at an independent specialist, or double that at a dealer.

BTW, if you have access to a code scanner that can read MB codes, try reading the codes: the engine may (though not always) log a fault 'P012800 The coolant temperature is below the coolant thermostat specified temperature'.

See also:

https://static.nhtsa.gov/odi/tsbs/2020/MC-10179907-9999.pdf

I would be really happy with £300 but it seems to be much more , independent £577 part and labour and my local garage wants to first do the diagnostic £60+vat p/h and exact for how long It might take him to do the job
The part costs £152 so it will be more than £300
Not warning light is shown just yet,
Looked all over the Internet but unfortunately no info regarding how to do the replacement

 

[markjay]

Where in the UK are you?

 

[Michael224]

Where in the UK are you?

Nottingham

 

[Michael224]

A gentleman suggested that it might be because of the recent cold weather and it might be resolved as it warms up again. Does anyone else believe it Could be the case !?

 

[BlackC55]

A gentleman suggested that it might be because of the recent cold weather and it might be resolved as it warms up again. Does anyone else believe it Could be the case !?

No, it will need replacing.

 

[Michael224]

Thank you for your support guys .
just wondering if Anynoe knows of any other videos or info regarding the replacement ?
There are a few on Internet but not the same layout and parts as mine

 

[SpikyMikey]

To give you some idea of the scale of the task of a 'simple' thermostat replacement on these engines, my trusted Indie (admittedly not a MB specialist) took 6 hours to investigate and replace the thermostat and waterpump and charged me £464 + VAT in 2022