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C300-2009
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52 Posts
Discussion Starter #1
hello all,

i have a 2009 C300 4Matic LS. It has 20k on it. The normal engine temperature i see is 90. Is this normal??? i have been seeing the same ever since i bought it..

appreciate any replies and comments.


Thanks.
-Reddy.
 

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2013 C300 Sport Darth V 3.0
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788 Posts
Mine runs between 75 and 80
 

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C300 4matic Special Edition
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53 Posts
My 2010 and the same year loaner that I had recently for 2 weeks, both stay at 90 deg all the time. Perhaps there was a change after 2008/9?
 

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272 Posts
My 2008 has been rock steady at 90 from day 1, no matter what the outside temp. is.

There only variance is how long it takes to get there, according to the outside temp.

HTH
 

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w204 (C350ELE)
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1,262 Posts
Of course these are ISO Celsius degrees (~195 degrees Fahrenheit).

To keep it right, correct cooling solution (components and quantity), plus correct thermostat (type and opening temperature), and correct operation of cooling fans (components, and controls).
 

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C300-2009
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52 Posts
Discussion Starter #6
Thank you all for your experiences. i think i don't have to worry about it.


Thanks.
-Reddy.
 

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2009 C300
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1 Posts
My 2009 C300 has 60k miles on it. The engine temperature always stays at 90 during operation. Was a little concerned about this, but now seems its normal. Thanks guys.

-Sharc
 

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2008 C300 Lux Black on Black
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68 Posts
My 2008 was well below 90 (75-80) for about three years. Then the dealership performed a software update that made the daily drive reading closer to 90. But everyone on this forum said that was a normal value.
 

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Premium Member
2013 C250
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7,273 Posts
Is the gauge really that accurate?
 

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2008 C230 4MATIC; 2008 ML320 CDI 4MATIC
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819 Posts
Mine has been running at 90c in most situations. Only if I am driving between 75-100km/h (50-60mph) at a consistent speed, the temp drops to 80c.
 

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2009 C300 Sport 6-speed M/T - & - 2009 B200 CVT
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47 Posts
All W204's with an M272 engine (2.5, 3.0, or 3.5) have an electronically assisted thermostat. The thermostat is a traditional wax pellet design with 2 chambers, but also has an electric heater element to allow the ECU to control the temperature within a desired range depending on outside temperature, engine load, etc.

The minimum operating temperature is 80C, and the maximum (according to WIS) is 100C, but I've never seen it go that high. In the winter, I find that my 09 tends to run at a minimum of 90C at all times (once fully warmed up, which can take a bit of time if you're doing all stop and go city driving in very cold weather). But in the summer, I find that the ECU allows the temperature to drop between 80-85C if you're out on the highway at higher speeds (140 km/h or ~88 mph).

My dad's 08 C300 tends to run a bit closer to 85C in both summer or winter, but does hit 90C and stay there if you're not driving it at constant high speeds (such as city operation). At 140 km/h, it will not go above 85C.

Different years and models of W204's must have very slightly different ECU programming.
 

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Premium Member
W220 2003 Update S500L, W204 2008 C220 CDI
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444 Posts
My 2008 W204 C220 CDI (2.2L Diesel with 70,000Km) was reading between 70C to 80C for over a year and would always fall below 70 when going down a long hill, ie with engine doing the braking.
Changed the thermostat (original one was stamped 92C) and the temperature guage now doesn't move off 92C (except when warming up of course).
Bonus is the fuel economy is now back to what it should be.
I have just done a 1,100Km trip (have yet to refuel and still have just under a quarter tank showing) and got the following;
At a constant 104 Kph (100 zone) get 5.2L/100Km.
At a constant 114Kph (110 zone) get 5.4L/100Km.
Previously the best I could get with constant driving speed was 6.4.
Resetting then driving around town get between 6.8 and 11L/100Km.
I find the down hill with engine braking, in a low gear if necessary, a good test of a thermostat function. With my new thermostat the guage just does not move off 92C.
Sent from AutoGuide.com Free App
 
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