PeachParts Mercedes-Benz Forum - View Single Post - 87 190E 2.3- getting hot/over heating in traffic -Solved

Greg in Oz · #4 02-18-2004, 01:32 AM

Snibble is talking about an M103 (6 cyl) which uses a viscous fan coupling whereas Haasman is talking about an M102 (4 cyl) which uses an electromagnetic fan clutch operated by a temperature switch. This temperature switch actually has two switches operating at two different temperatures. The lower temperature switch energises the clutch for the engine driven fan and the higher temperature switch activates the electric fan in front of the radiator. On the M103 the equivalent temperature switch is only used to activate the electric fans. The engine driven fan couples by way of the temperature of the viscous coupling (determined by the air temperature flowing past it).

I much prefer the arangement on my M103 to that on my M102. I do not like the way the M102 idling in traffic receives no airflow until at 100 degrees C when the electric fan clutch engages. At idle in very hot conditions the engine driven fan (turning relatively slowly) struggles to prevent the temperature rising any higher. When accelerating after the traffic begins to move, the fan roars with higher engine speeds since it has no speed limiting feature such as that with viscous couplings (and the power it requires can even be felt if it switches on or off while accelerating).

I have performed a simple modification to my M102 (190E-2.3) where I have swapped the roles of the fan clutch and electric fan. By swapping the appropriate wires at the dual temperature switch my electric fan switches on first at 100 degrees C. This quickly brings the temperature back down below 100. If the temperature was to continue to rise (which it never has) the clutch would engage the engine driven fan at 110 degrees. Whilst the electric fan is noisy outside the car, it does not intrude into the interior the way the engine driven fan does at higher engine speeds. I am cosidering looking into a further modification that would run the electric fan at the lower speed (as used by the air-conditioner) at 100 degrees and then switch it to the higher speed at 110 degrees (when the fan clutch engages) should it ever reach this temperature. At the high speed the cooling appears to be more than required and the low speed would reduce noise levels outside the car. This mod would require more work than simply swapping two wires at the temperature switch as I have currently done.

One word of warning to anyone who would like to try this modification, ensure that the wiring to your temperature switch will allow this. On my M102 both switches switch to +12V. I believe that some versions may be different (eg. M102 used on a W124). As with any modification, you should be absolutely sure of what you are doing.