Hi fellow W203 owners.

I'm a new owner to a W203 Sport Coupe C180 kompressor. I'm curious to know how accurate is the temperature readout on the digital display? As I am fixing and testing things out I noticed the temperature gauge move up slightly under hard acceleration.

I am aware coolant temperature fluctuates but I am also aware not all cars reflect it. For example I own both a 2010 C207 E350 and a 2010 W212 E350 4matic both with the M272 engine and when the needle reaches ~95C (which is where it stays) I cannot get it to move no matter how hard I drive them. I'm planning to hand the W203 to my girlfriend as a gift and I'd like to know if I am looking at possible cooling issues before she overheats the engine due to ignorance / neglect.

This is how high it goes and is also the temperature at which the fan kicks in. Under normal driving it sits perfectly at the middle between 80C and 100C.

 

It's accurate if the coolant is at the correct level. The sensor is attached to the plastic pipe that runs along the R side (facing the direction of the car) of the engine, above the exhaust manifold.

The thermostat is set to open at either 87C or 90C (MB had 2 versions in the past but now only sell the 90C one), which is exactly what you're seeing. When the thermostat fails, the car fails to reach operating temperature (it will run cool) and the car will throw a CEL.

 

Looks good, but in general the sensor and thermostat do not work forever. I had a faulty temp sensor which was 10 deg C off, leading in too rich running on cold start. When it was 10 °C outside it's reading was 0°C and enriched the mixture.

 

Appears at operating temp it stays the same. Probably similar to the 207. Seems similar to my W204.

This is from a 2005 W203 manual. https://charm.li/Mercedes%20Benz/200...2C%20Function/

 

That explains what I have seen after replacing the radiator. Temp was higher measured with a probe than in the display. Everybody is lying to you these days.

 

Thatsgood to know and in general it applies to all new-ish vehicles.

 

My thermostat gave out after 22+ years. No fault came up. Just took a long time to warm up, and get heat in the car, and then went down
when you idled a while. The taking so long to get the car warm ie the interior heat was the big clue. I had one sitting on a shelf for years from the
Mercedes "extreme couponing" days ($100 per coupon for free stuff and you could print as many as you wanted) , swapped it, and ez peazy, it was fixed.

 

I have a 2010 C300 4matic sport with 160,000 miles on it, has the M272 engine. I noticed oil seeping from around the oil filter housing so decided to replace the two gaskets in there last year which involved removing the thermostat to remove the bolts of the housing. I was going to replace the thermostat while at it but realized it is fairly easy to replace on its own so instead just replaced the gasket and o-ring for installing it back on. No idea if its the original thermostat though it is a Genuine Mercedes and the Carfax history is pretty detailed with all previous work done on it from previous owners.

Point of my story is I noticed the thermostat is stamped Wahler and from memory it was also stamped 100 degrees Celsius on it. Not sure who makes the M271 thermostat, probably Wahler also.

For the M272 gaskets I didnt even drain the radiator, just unbolted the oil filter housing and let it drain down onto a large pan below to collect all the fluid. I even left the thermostat on the hose, just unbolted and moved it up out of the way. I did this to not disturb the o-ring in the hose and also to not disturb the wires on the thermostat. Also got away with not having to remove the secondary air pump by using small 1/4" drive sockets and extension that just barely the tight space. One thing I found odd is the operators manual says the cooling system takes 4.8l of coolant but I over 5l back in, and I didnt even do a full complete drain since I didnt touch the radiator drain.

 

Wow. Didn't know that. Learned something new.