How to test if fan clutch is working

Car is a 92 300e. Recent new radiator & water pump. Yesterday engine temperature was around usual 80 degrees when on the freeway, but went up to
around 100 when stationary in city traffic. The A/C was not on. This is making me think that the fan clutch is no longer functioning, so the mechanical fan isn't spinning when the engine is idling. I'd like to test this before shelling out $200 for a new fan clutch, any ideas how I can do this?
Thanks, Chris
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Turn the fan by hand when cold and compare to turning force when hot..over 100. Engine off of course. If the fan clutch is OK you should feel more resistance when hot. Peter

to
mechanical
before
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On 2004-10-20 09:16:07 -0700, snipped-for-privacy@aol.com (CRGILL) said:

This seems normal in my experience, the fan clutch thermostat doesn't trigger till over 100 degrees (110 in some cars). It's very simple to pull the wire off the sensor (with the engine off obviously), and tie the wire to a good ground. Then try putting the key into the running position, you should here a click and the fan clutch should be active.
You can even start the vehicle at this point assuming your make sure the wiring hack isn't in the way of any moving parts and watch the fan turn.
I bet it works fine.
marty
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Could it have been CRGILL who typed:
|| Car is a 92 300e. Recent new radiator & water pump. Yesterday || engine temperature was around usual 80 degrees when on the freeway, || but went up to around 100 when stationary in city traffic. The A/C || was not on. This is making me think that the fan clutch is no || longer functioning, so the mechanical fan isn't spinning when the || engine is idling. I'd like to test this before shelling out $200 || for a new fan clutch, any ideas how I can do this? || || Thanks, Chris
Use a carrot! if the engine is very hot put a carrot to stop the blades when the engine is running, if the carrot stops the blades the clutch not activating, if the carrot slices (for the soup!) then the clutch is OK. Better than using your fingers!!! A lot of overheating problems IME are caused by inefficient radiators, maybe not leaking but they do lose their efficiency over a number of years so a replacement radiator can cure a lot of overheating problems.
Des
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<snip>

I radiator is an expensive part to throw at a problem. Thermostats are much cheaper. Try the simple stuff first. Testing all of the fans/sensors first makes sense.
marty
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clutch fans when first started in the am should lock up when first stared <cold> and then after a short time slowdown .
the way i tested mine on other cars is start and bring the RPMs to 2,000 with the hood open <first AM start> so you can hear it or better yet get helper and stand by the fire wall. you will get a good wind off it till it slows its self down.
100 C is only 212 F
the case, minus a few cans!
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