w201 (102) overheating problems

**ralliart17** · June 18th, 2010 02:15 AM

hi again...

having w201 (102 engine) is having overheating problems lately... my 1st suspect is the cylinder head gasket (just have them replaced) - what is the correct torque on the bolts to fully secure the head, noticed that the water is coming out of the reservoir on idle (after overheating).

is it advisable to remove the stock propeller and convert to an auxfan type coolling (ala front wheel drive)?

please help.. can't bring out the car on a hot day..

thanks in advanced.

**busdriver** · June 18th, 2010 11:30 AM

Originally Posted by ralliart17

hi again...

having w201 (102 engine) is having overheating problems lately... my 1st suspect is the cylinder head gasket (just have them replaced) - what is the correct torque on the bolts to fully secure the head, noticed that the water is coming out of the reservoir on idle (after overheating).

is it advisable to remove the stock propeller and convert to an auxfan type coolling (ala front wheel drive)?

please help.. can't bring out the car on a hot day..

thanks in advanced.

Same here ralliart. My S124 (M102 engine) overheated yesterday.
I guess its really the weather.
On the other hand, the engine should not overheat when everything is working normal.

my 1st suspect is the cylinder head gasket (just have them replaced)
if no water leaks from the engine, then the repair should be ok

noticed that the water is coming out of the reservoir on idle (after overheating)
this is normal because in a Benz the reservoir is an integral part of the cooling system. Water (ie steam if overheated) circulates in the reservoir as well, unlike Jap design reservoir.

is it advisable to remove the stock propeller and convert to an auxfan type coolling (ala front wheel drive)
what I did with my S124, I just fully engaged the main fan clutch in such a way that the fan always rotate with the engine. Sayang naman yung fan kung tatanggalin.

How's your radiator cap? Any noticeable leaks? Mine is bad, water is coming out of it. That's my suspect since the cooling system is not a sealed system anymore. That little leak from the top slows the circulation of water to/from the engine.

I'll keep you posted on my fix. pls update us too. Thanks. Goodluck.

**ralliart17** · June 19th, 2010 12:50 AM

Originally Posted by busdriver

Same here ralliart. My S124 (M102 engine) overheated yesterday.
I guess its really the weather.
On the other hand, the engine should not overheat when everything is working normal.

my 1st suspect is the cylinder head gasket (just have them replaced)
if no water leaks from the engine, then the repair should be ok - no water leaks naman and the oil is normal, di sya naging parang milk shake. To be on the safe side, I have it re-torqued, imikot pa sya ng half turn, i'll still have to take it our tomorrow, to test.

noticed that the water is coming out of the reservoir on idle (after overheating)
this is normal because in a Benz the reservoir is an integral part of the cooling system. Water (ie steam if overheated) circulates in the reservoir as well, unlike Jap design reservoir. - may mga cracks na din yung reservoir ko, pero its a good thing na din, dun lumalabas yung pressure instead sa radiator..

is it advisable to remove the stock propeller and convert to an auxfan type coolling (ala front wheel drive)
what I did with my S124, I just fully engaged the main fan clutch in such a way that the fan always rotate with the engine. Sayang naman yung fan kung tatanggalin. - ganyan na din ginawa ko sa fan, naka epoxy na sya so kasabay a sya ng engine.

How's your radiator cap? Any noticeable leaks? Mine is bad, water is coming out of it. That's my suspect since the cooling system is not a sealed system anymore. That little leak from the top slows the circulation of water to/from the engine.- if the temp reached 100+, may steam na lumalabas.. pero wala naman dun sa cap area..

I'll keep you posted on my fix. pls update us too. Thanks. Goodluck.

- i'll keep you posted. pag ok yung re torque ng bolts, I may change the oil and put in some coolant..

thanks!

**gmd** · June 19th, 2010 06:06 AM

Good day/pls.check your engine thermostat and the radiator maybe clog need be cleaning,air trap on engine cooling block

**HBOY** · June 22nd, 2010 02:15 PM

I cant really say it is the weather.. MBs are available also in other countries where it is hotter. But I'd have to agree with the post above. Check your thermoswitch and thermostat. You may have a higher rated thermoswitch and thermostat, whereby it delays the opening of the water flow as well as the aux fan. My 124 is still running its magnetic fan clutch in stock form, but I've replaced my thermoswitch with an 85 deg rating. Meaning at 85 degrees, the High speed aux fan turns on. The low speed aux fan only engages when AC compressor kicks in... otherwise the aux fan is off. My thermostat on the otherhand opens at an early stage of 72 degress. Meaning before this temp, the cooling system is in close loop, thereby letting the engine warm up faster in the morning, after that, it is simply in open loop.

**busdriver** · June 22nd, 2010 02:59 PM

*HBoy.
Hi. Is there any other culprit besides this thermostat switch?

I mean, mine, everything was working perfectly. I have the 85 thermo switch as well. The aux fan was running when it over heated.
I even replaced the orig. aux fan with a stronger one (more blades) since I have the European version. (car from Germany)
I'm still clueless what happened that day.

**mbeige** · June 24th, 2010 03:07 PM

Not sure if the 190E 2.3 has only one auxiliary fan. The 2.6 has two, it might be a good upgrade.

Our first summer with working AC on my 190E 2.6, both aux fans run at high speed in idling city traffic conditions. No over heating on mine, all stock. Radiator was replaced in 2006 (Nissens). Have not dug in to thermostat, water pump or viscous fan clutch but cap is new. Owned by my friend who did a lot of work on the car.

In city traffic the temp would rise to 85C, max of 90C with aux fans blowing hard while idling in traffic and AC on.

What's the condition of your cooling system? Radiator original? Water pump original? Thermostat rating? Fan clutch condition? (m102 probably has electromagnetic type) Check condition of radiator cap. Spring can weaken over time. Replace with "140" instead of "120" for higher safety margin (releases pressure at a higher temperature/pressure, meaning it will have a higher threshold).

I suspect it will get hotter over here, but I'm confident in the car.

**HBOY** · July 8th, 2010 05:49 PM

Originally Posted by busdriver

*HBoy.
Hi. Is there any other culprit besides this thermostat switch?

I mean, mine, everything was working perfectly. I have the 85 thermo switch as well. The aux fan was running when it over heated.
I even replaced the orig. aux fan with a stronger one (more blades) since I have the European version. (car from Germany)
I'm still clueless what happened that day.

though the aux fan is running, it may not be operating at high speed when temp is compromised. To check, run your car, open ac, your aux fan may be running by this time at LOW speed (temp should be below 85 deg). to check if your fan has HIGH speed function, you can ground the terminal (the one that is supposed to activate the High Speed aux fan). If you hear an increase in speed of the fan, the high speed is operational (Remember the difference in sound), if not check for connection problems such as the resistor and other connections to the aux fan setting. Now the question is, if the thermoswitch activates it once the 85 degree temp is breached. Easy enough to test, run the car normally, as you've said your car overheats, so when temp goes over 85 degrees, listen to your aux fan, if you hear that it is only running at low speed, then replace thermoswitch.