QuestionQUESTION: I just purchased this car a week ago. I noticed while I am driving the temperature stays around 90 C. While I stop the temperature goes up almost to 120 C but does not reach the red mark. The two electric fans are running on high speed when this happens although the mechanical fan I can stop it from running by hand while the engine gets hot. I just removed the thermostat yesterday and after removing the thermostat the engine goes very quick above 100 C almost to the red mark and that is while I am driving. There is no play in the mechanical fan clutch although I can not feel much drag on it while hot. Is my radiator clugged ??? and there is no bubbling back in the radiator while the engine running neither steams out of exhaust or any indication the head gasket might be blown. please help
ANSWER: Radu,
The engine temp unit should be a direct read of the engine temp,and thus, will fluctuate more that an American vehicle. The proper operating temp is between 80 and 100 C.
It is important to have the proper ratio of antifreeze and water. 50/50 is usually the correct amount. This can be checked with a hydrometer. If you have extreme winter, then you should add more antifreeze. Do not guess at the amount, check with the a Dealer or Mercedes mechanic.
The radiator cap should be checked for proper seal.
The cooling system must operate under pressure to allow the coolant to increase without boiling out.
The thermostat should not be removed. I would make sure that you have the correct thermostat and install a new unit.
The coolant recover tank must have correct level of coolant.
If the system has been opened then air is entrained into the circulation system. The recover tank, allows these air pockets to be burped out over time, during the heating and cooling cycles.
When the system cools, the caps allows water to be drawn back into the radiator to displace the air that was burped out.
If the recover coolant level gets too low, then air will be drawn back into the engine.
Be sure that your fan belt is properly adjusted and the your mechanical clutch is operating properly. You should feel resistance when trying to rotate the fan blade against the belt pulley.
Your axillary fans should be operating full time when the AC is operating and when the engine temp rises, as in traffic.
120C is certainly getting above the normal range.
If the system has not been flushed properly, then, I would contact a radiator shop and as the best way to properly clean the circulation system.
Always use caution about removing the radiator cap, as the liquid will be under considerable pressure and can boil out into your face and hands.
Good Luck
rob
---------- FOLLOW-UP ----------
QUESTION: thank you so much Rob. I have all the shields in place. Radiator cap appears to be alright as the system does stay pressurized. I drained the antifreeze today and replaced it with radiator flush liquid bought at an aftermarket parts store and added straight water up to the mark in the reservouir. As long as I keep moving and with the A/C off I stay about 95 C that is moving. If I stop then it climbs above 100 C. about 110 C the auxialiary fan kicks in then I still need to get moving or temperature will climb towards 120 C mark. I am inclined to think based on a little bit of knowledge with mercedes and based on one of your posting here that I either have a bad fan clutch or worst the catalytic converter clugged ??? is my temp sensor out of range as the electric fan should kick in at lesser temp then 110 C ? the car appears to have a newer behr radiator. and again does not give any indication of a blown head gasket as there is no bubling or steams or any rough idle Appears that i have problem with the air flow from what I can make or something clogged be that cooloing system or catalytic converter ?? what else should i consider doing besides taking the car in to the Mercedes dealer ?? and thanks again. oh and one more thing, when the engine is hot I dont feel much drag in the mechanical fan but with the electric fans both running I can feel plenty of air coming to the engine.
AnswerRadu,
The when the vehicle is hot, this is the time that the clutch should have the fan blades locked to the drive pully.
I would think that if you took the vehicle to an emission station, that a clogged catalytic converter would show up on their diagnostic.
Remember that it is important to NOT have just water in the system. The added coolant make the liquid more effective in removing heat from the engine.
Make sure that your oil is the proper weight. 5W30 and is clean and full. Oil has a lot to do with removing heat from the system too.
Be sure to open the heater to the high position when changing coolant to make sure that the mixture is completely circulated, and any potential bubbles of air are removed from the system.
Additionally, if the ignition timing is too advanced, this will cause the engine to operate at higher temperatures.
A Clogged converter will also cause poor performance during acceleration.
Make sure that this radiator is the proper unit for this year and model vehicle, some time they look the same but are structurally different.
Good Luck
