New Thermostat

johncroydon

Senior Member
Joined
Mar 3, 2013
Messages
246
Reaction score
0
Location
croydon, surrey
Your Mercedes
w204 c180 amg sports plus 2013
In my quest to replace anything showing signs of wear, it's now the turn of the thermostat!
In the cold weather it struggled to get above 70c on a 10 mile journey. On a run it would reach 90c but drop to 60c. With this hot weather it reaches 90c within minutes. It will no doubt be adequate if i leave it but the thought of luke warm air in the cabin from October to march has pushed this to the top of my list.
Not attempting this myself, my usual guy will be doing it on my drive, with me discretely reading the "how to" from this forum, while looking over his shoulder, a mechanics nightmare lol.
Rather than just topping up was thinking of draining and refilling. I have a gallon of mb antifreeze so plenty.
I take it there is no drain to the bottom of the rad? Didn't really want to disturb bottom hoses etc if can be avoided.
john
 

EmilysDad

Senior Member
Joined
May 8, 2012
Messages
11,074
Reaction score
4,367
Location
Bury Lancs
Your Mercedes
ML350
In my quest to replace anything showing signs of wear, it's now the turn of the thermostat! ....

To test your 'stat .......

start your car from cold & keep your hand on the top rad hose. If it slowly warms up as the engine warms up, then it's stuck open - which, by your description of engine temps, sounds like yours is. The top rad hose should stay cold till the 'stat opens & then get warm all at once. ;)

No idea whether you have a drain on your rad or not, but if you're paying someone to do the job for you, you don't need to know! :lol:
 
Last edited:

S.Speed

Senior Member
Joined
Apr 12, 2009
Messages
5,066
Reaction score
12
Location
Lancashire
Your Mercedes
Older Citroen Now :-(
Hi John..
Yes there is a drain at the bottom right of the radiator..
Undo the under tray at the front (under the bumper) and flex it down .. You don't need to totally remove it..
You will see a tap / valve..
Do remember to tighten it back up once you have drained and flushed..:)
 

Pathfinder

Senior Member
Joined
Dec 21, 2011
Messages
814
Reaction score
18
Age
61
Location
Gourock
Your Mercedes
CLC 220 CDi Sport Diesel Year 2008
When I served my time, we used to do a reverse flush of the system.
 
OP
J

johncroydon

Senior Member
Joined
Mar 3, 2013
Messages
246
Reaction score
0
Location
croydon, surrey
Your Mercedes
w204 c180 amg sports plus 2013
  • Thread Starter
  • Thread starter
  • #5
Thank you for all the replies, most useful.
looking forward to getting it done, just hope it improves the warm up time during the winter months!
john
 
OP
J

johncroydon

Senior Member
Joined
Mar 3, 2013
Messages
246
Reaction score
0
Location
croydon, surrey
Your Mercedes
w204 c180 amg sports plus 2013
  • Thread Starter
  • Thread starter
  • #6
Hi John..
Yes there is a drain at the bottom right of the radiator..
Undo the under tray at the front (under the bumper) and flex it down .. You don't need to totally remove it..
You will see a tap / valve..
Do remember to tighten it back up once you have drained and flushed..:)

hi simon,
great stuff, thanks a lot.
john
 
OP
J

johncroydon

Senior Member
Joined
Mar 3, 2013
Messages
246
Reaction score
0
Location
croydon, surrey
Your Mercedes
w204 c180 amg sports plus 2013
  • Thread Starter
  • Thread starter
  • #8
To test your 'stat .......

start your car from cold & keep your hand on the top rad hose. If it slowly warms up as the engine warms up, then it's stuck open - which, by your description of engine temps, sounds like yours is. The top rad hose should stay cold till the 'stat opens & then get warm all at once. ;)

No idea whether you have a drain on your rad or not, but if you're paying someone to do the job for you, you don't need to know! :lol:

Thanks for the tip
Wish i had that basic knowledge before i went out and spent £75 pounds on thermostat and antifreeze :Oops:
Guess it wont do any harm to change it anyway, its done over 70, 000 miles so must be a bit tired to say the least.
john
 

S.Speed

Senior Member
Joined
Apr 12, 2009
Messages
5,066
Reaction score
12
Location
Lancashire
Your Mercedes
Older Citroen Now :-(
Thanks for the tip
Wish i had that basic knowledge before i went out and spent £75 pounds on thermostat and antifreeze :Oops:
Guess it wont do any harm to change it anyway, its done over 70, 000 miles so must be a bit tired to say the least.
john

John..
IT NEEDS CHANGING..
Its well known that the thermostats on these engines last 2 minutes..
We have talked at length on the phone and yours DEFINITELY needs doing!
If I was nearer I would do it for you..
Don't fester about it.. It will be fine once its done.
Did you manage to find out the capacity of the cooling system?
The reason I suggested you pre mix the antifreeze is because its unlikely you will be able to drain all the coolant.
You need to undo the drain tap on the engine block (which is a sod to reach from above) if you wish to drain fully..
By pre mixing you keep to the recommended strength..
Remember to keep a litre of pre mixed in your car for a couple of days after the thermostat renewal.. It WILL need topping up as the air expels.
 
Last edited:
OP
J

johncroydon

Senior Member
Joined
Mar 3, 2013
Messages
246
Reaction score
0
Location
croydon, surrey
Your Mercedes
w204 c180 amg sports plus 2013
  • Thread Starter
  • Thread starter
  • #10
John..
IT NEEDS CHANGING..
Its well known that the thermostats on these engines last 2 minutes..
We have talked at length on the phone and yours DEFINITELY needs doing!
If I was nearer I would do it for you..
Don't fester about it.. It will be fine once its done.
Did you manage to find out the capacity of the cooling system?
The reason I suggested you pre mix the antifreeze is because its unlikely you will be able to drain all the coolant.
You need to undo the drain tap on the engine block (which is a sod to reach from above) if you wish to drain fully..
By pre mixing you keep to the recommended strength..
Remember to keep a litre of pre mixed in your car for a couple of days after the thermostat renewal.. It WILL need topping up as the air expels.

Thanks simon
i guess was just trying to justify to myself more expenditure on something that has not completely failed.
Think i read somewhere it takes around 8.5 litres, but will google it to check. As you say it seems unlikely we will manage to drain it completely anyway, and i have 5ltrs of concentrate from mb, so more than enogh. Incidently it was only £30 which i thought was real good.
I will take it on a run hopefully sunday to see if there is a difference in Stat performance, before it would drop down to 60c. Though might be best to try it when it's a bit cooler outside.
Thanks
john
 
OP
J

johncroydon

Senior Member
Joined
Mar 3, 2013
Messages
246
Reaction score
0
Location
croydon, surrey
Your Mercedes
w204 c180 amg sports plus 2013
  • Thread Starter
  • Thread starter
  • #11
So, thermostat changed today, along with the oil filter because thought it wise to change the seals too, My local MB did not supply oil filter seals only.
We found the short stubby pipe very fiddly to get back in position, but that was about the only drama. I must admit the job was a little beyond me, and was glad my usual guy was on hand, that pipe required patience, plus he has more tools!
Drained the coolant from the buttom of the rad only, thought it best not to touch the block drain plug, the coolant did come out very clean though.
Managed to get about 6lts of 50/50 mix back in which was about what came out. Will keep an eye on levels over next day or two, and performance, engine warm up wise.
Another job ticked off the list :D
john
 


AMF Automotive - We are an independent Mercedes-Benz and AMG specialist located in Paddock Wood, Kent, with full Mercedes Diagnostic equipment. We offer a full portfolio of tuning options for AMGs and can cater for all your Mercedes needs.
Tel: 0203 384 4644www.amfmercedes.com/
Top Bottom