W204 2012 220 CDI - new thermostat housing

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220problem

New Member
Joined
Jan 23, 2022
Messages
24
Location
East Mids
Car
Mercedes C Class C220 CDI
Hi,

I haven't posted many issues on here, but i'll get straight to the point.

I have recently started to experience some issues with my w204 C220 - 140K on the clock (motorway mileage)

Over the year I have had, DPF cleaned, DPF sensor, new EGR Valve, transmission mount, oil mount and most recently new water pump which has been great for the past 10k miles and now the latest new thermostat housing.

Symptoms before new Thermostat housing; temperature on the dashboard fluctuates bouncing up and down, it would only go up to 90 never higher but hovers around 80, but frequently sits at 40 and 0 for a few seconds when driving on the motorway. Jumps into limp mode on hard acceleration around 60mph+ on high revs.
Heating set at fan speed 4 and 21 degrees.

Symptoms after new Thermostat housing installed; driving on the motorway and temperature was good for 10 mins on 90 then slightly dropped to 80 mark and then bounces to 40 and 0 and then when stationary sits at about 40 and 80 again. After a 20 mile drive no limp mode which I was pleased about.

Heat from the fans blows a heavy load of hot air than it feels cooler for a bit and then the hot air again.

I've spent so much money on this car with all the engine management lights and limp modes, that I am now asking for help. I can't afford to keep going to the mechanic and when he scans through STAR nothing appears, and its all working fine.

What could be causing this temperature and heat shooting out?

Thanks for everyone's input.
 
Without standing over the car I can only guess, but a couple of things that come to mind are an air lock or a faulty water pump.
 
Without standing over the car I can only guess, but a couple of things that come to mind are an air lock or a faulty water pump.
Thank you... I went for a 2.5 hour drive this morning and the thermostat stayed between 80 - 90 degrees but heater was blowing out hot/cold air. My car settings were at 22 degrees heat direct at me, footwells and windscreen heat.

Not sure now why it is blowing out hot/ cold air, it has happened before I did notice it months ago, but then the temperature in December wasn't cold where I was.

Any ideas what this could be?
 
Will this give me an EML or an error code on Star if it fails?

Do you know a rough cost of the part and fitting? (Just a general idea)

Amazing these cars are, you fix one thing and two months later another thing, but I'm glad the thermostat settled in.
 
Failed duo valved would not throw an EML. Not sure if Star would pick it up, however you could do an actuation test on the valve with Star to check if it operates as it should.
 
Failed duo valved would not throw an EML. Not sure if Star would pick it up, however you could do an actuation test on the valve with Star to check if it operates as it should.
Thanks, i'll have a look when I go to the garage, i've got an icarsoft v3 but I might leave it to my mechanic to test
 
I'll suggest you do actuation test on the valve with Star to check if it operates well..
 
Thank you all for your help guys, I have new problems that I have to create a new post for.
 

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