Electric Aux Fan Wearing Out?

[emerydc8]

Does anyone know if the MB electric aux fan motors weaken with age? I noticed that it is fairly easy to slow my fans down significantly, when they are operating in low, by just putting my hand around the front hub and applying pressure.

I've heard that an "unofficial" test for the viscous fan clutch is to carefully stick a rolled up newspaper in the fan blade while it is running and hot. If you can manage to get the fan to stop or slow significantly (without injuring yourself, of course), the clutch is worn. If the fan shreds the paper and keeps going, it is probably okay.

I was wondering if there is any quick and dirty way to see if the electric fans are worn. After over 230,000 miles in the Arizona desert, I'm wondering if replacing them would improve cooling capacity for the summer.

I replaced my radiator about 100,000 miles ago and I've flushed it out regularly over that six year period. I think it's still okay. I just replaced the thermostat and water pump too. I noticed, however, that while idling with an outside air temperature of 72 F, once the high fans came on (I have the Cool Harness modification that sets them off at 92 C coolant temp), the fans (and maybe the radiator) are not capable of getting the temperature back down to the point where the high fans should normally turn off (I think that is about 85 C with the Cool Harness). The coolant temp seems to stagnate right above that point (around 85-87 C) and never cools lower than that, unless I drive the car. This occurs with the a/c on or off. BTW, with the a/c on, the vent temp was running a steady 39-40 F at idle.

It's no big deal, and I probably wouldn't have noticed it at all with the normal 105 C trigger for the high fans. But I was curious as to whether the efficiency of the cooling system could degrade with wearing aux fans and, if so, how can one determine whether they are worn.

Any thoughts?