Hello to all, I have just bought myself a 1995 s500 with 80k miles on. One owner car with full dealership service history. The last cuople of days was really hot here about 93-95. In stop and go traffic the coolant tempreture goes to just below 120 celsuis mark, then I can hear the electric fans engageging and the temp drops to around 105 celsuis. Highway driving sees the coolant at a steady 100 degrees celsuis. Sorry my cars guage is metric. at night the coolant tempreture is about 85-90 degree celsuis.

is this normal or is my visco clutch acting up (81k miles??)

Thank you in advance

'Mind you I'm not a Petrol Operator.

BUT JIM is the W140 Man:

K6JRF Auto Page

(Look at # 17 and #18)

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'84 300SD sold
124.128

How to change Aux Fan cut-in point

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'84 300SD sold
124.128

Most 1995 W140 chassis had aux fan issues, do you have 2 white ballast resistors
mounted between the aux fans?

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MERCEDES Benz Master Guild Technician (6 TIMES)
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44 years foreign automotive repair
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MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

My '95 S500 coupe runs about 105c with peaks at 110c during stop and go traffic during the real hot season, and hovers around 100c when moving. The only change that made any appreciable difference was the viscous fan mod in the link that compress ignite gave. It seems that once the coolant temperature exceeds 100c or so it's harder for the cooling system to "catch up" or maintain under 100c temps. I originally replaced the thermostat, radiator, water pump and viscous clutch. I now keep the altered one (I shortened the pin enough that the clutch is always engaged) for the summer and switch to a stock clutch the rest of the year as there is some difference in fan noise with the altered clutch. Another trick is to reduce the ratio of coolant to water to 40/60 during the summer, as that helps keep operating temps down a tad as well.

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1983 380SL
1995 C280
1995 S500 coupe
1990 Mazda Miata
2004 Suzuki Hayabusa

MB DOc : Thankyou for the replay, but no there is no ballast resistors between the fans, the fans do come on at arround 115 degrees on a very high speed, and then the tempreture immediatly drops to around 95.

Pili380sl: I also did the pin conversion yesterday, and when I replaced the visco it did draw much more air than previously, and you could actually hear it roar at around 2000rpm. This however lasted for about half an hour then the visco lost its bite again, the conversion still in place. So I deduct that the visco as had better days.??

I followed the procedure in the link provided and installed the 1000ohm resistor in parallel, it made a huge diffrence car now runs at 98 degrees celsuis in traffic and 85 on the highway. I will replace the fan clutch just for good measure because it is definately not pulling like it should. Thanks guys!!