Patrick - From what I can see from the video the fan is working exactly as it should which means the temp sensor is working. The controller is working & the fan motor is working. What I can't hear properly or see is if the fan is spinning fast enough. That said. With no airflow through the radiator from driving the car it gets the temp back down to 90 just fine. If the fan does this everytime the car gets to 95 - I don't understand how it can ever get to over 100 degrees. There is something screwy here.

OK - next move. Please drive the car & try & get it over a 100 degrees & jump out & see if the fan is howling it head off. You can clearly hear the fans on these cars. As you say they make a hell of a noise. If the fan is howling it's not the fan or fan circuit.

We have to make a move hear & while splinter is correct in his many usefull posts that a Merc thermostat is designed to fail open & cause the car to run cold - I'm becoming suspicious of your themostat. 84 degrees is too cold for this engine & 104 is too hot. Thermostats are cheap. Please replace the thermostat to get it out of the way. I think we have a faulty thermostat here if the fan always behaves as it did in the video.

BTW - Sensor 146 is inserted into that long rubber pipe.

 

hey Patrick what's the deal with the car man? Did you take care of it? If you need help let me know

 

hey bro.. just woke up and saw your text.. wont make it.. got plans. haha. the car??? haha drove it for the first time in a week last night. its really freakin weird. temp stabled at 86 then in an instant it became 91 then in another instant dropped to 87, this all happened in a span of 1 minute. might be the sensor glyn is referring to. its like a $6 part. so im gonna change that and see if theres a diff. also weird thing happened, got a car wash so naturally when id get home the car would drip some water. was unloading my stuff from the car and noticed a big stain on the ground. dunno if it was there already or not.. i touched it and it was slimy. thought it was coolant but it was like a golden orange color. checked all fluids and everything was ok. im thinking theres a tranny leak since tranny fluid is red. but oh well.. im gonna observe this new thing AGAIN. i will replace that sensor after the holidays. hopefully that fixes this prob. if not next step is to actually test the fan. then from there ill decide my next move. BTW the ECT(146=engine coolant temprature sensor) Isnt it suppose to throw a P0115 error on the OBD. P0115 is for the ECT and thermostat if one goes bad.. just curious.

 

It wouldn't be the thermostat... the thermostat is not designed to regulate the minimum temperature. Because the copper spring is located on the engine side it actually regulates the maximum temperature. The minimum temperature is regulated by the efficiency of the radiator, the thermostat's regulation of the minimum temperature in any way is passive and not the specific intent of the thermostat. Look you can run a car without a thermostat and it the only ill effect you might have is that your car just simply wont get warm enough to provide you with cabin heat. But if the thermostat was stuck or malfunctioning then it would not be opening and you would be overheating regardless if you were driving or at idle. Additionally, It couldn't be a blocked radiator because when you speed up then you are providing heat exchange through the radiator, when the engine cools down then you know that the cooled fluids from the radiator are doing their job and there is no blockages preventing them. All this means is that your engine fan is not kicking on the way its supposed to. AKA You have a bad fuse, bad relay, bad fan, or one really confused ECU. You said that the fan was moving slow and when you pushed it moved faster? If it was at full speed then you should be afraid to even put your fingers near the thing. The fans bearings could be going which would case a lot of vibration and eventual motor break down (through excessive brush wear) and cause low torque which in an electrical fan means low cfms. The last thing that you could check is the coolant level... if your car is having to build pressure to get the coolant volume up to get it to move than you could see a fluctuation of temperature but it would be more than a couple degrees unless you are almost on the money. I still am convinced its your fan. Also your air conditioner and the engine fan have little to do with each other at all so its no surprise its not kicking the fan on.

**its late and im tired so my grammar sucks.. i corrected what i could **

 

The Benz thermostat is supposed to fail open. In reality I've seen thermostats do all sorts of things they are not supposed to.

 

Hey guys,

Just to confirm, the fan isn't designed to kick in until around 100 degrees? That's what I'm experiencing with my 2003 C240 M112 engine. The engine seems pretty stable around 87-90 degrees while driving but can climb up a bit at idle. I don't see the fan kicking in until around 97 degrees which seems a bit high to me.

Thanks!

 

Sounds like your car is performing normally to me.

 

Any grass seeds or insects blocking airflow in your radiator ? Correct coolant ?

 

Radiator is clean and works well when moving or when the fan kicks in. Xerex G-05 coolant is 1 yr. old. It just seemed the fan takes it's time kicking in while stationary. However, perhaps that's just the default behavior. Many people claim their cars are quite stable around 87 degrees so I just got worried. Especially with the incredibly hot summer we just had in Texas (90 days of 100+ temperatures).

 

87-90 is the correct temp range for these cars.