I'm considering replacing the clutch on my stock clutch fan. How will I be able to tell if the fan clutch is bad?

 

If there is oil leaking from the clutch, it is bad. If not-

If the engine is cool room temp: Engine off, the fan should turn but should not spin freely when you spin it with your finger. No more than a quarter to half turn

If the car is at operating temp: Engine off the fan clutch should be tight, hard to spin or turn much at all.

Compare the difference between cold and hot. If the difference is not substantial, then your fan is bad.

Also, if everything else works right and the engine is getting warm in operation, the fan clutch is suspect.

 

Engine cold and engine hot, the fan turns the same by hand. (Half spin)

 

Well, is it running hot? I've had a completely failed fan clutch make temps shoot way up at idle

 

This for sure, if it's hard to turn, engine cold, it's bad.

 

It's not running super hot. I just freak out when I see a 204° F... It's just how my mind works. lol - I see the water temp go up a bit and then think it's going to overheat, but it hasn't. The temp goes down at idle... so I assume the fan works. The stock clutch fan is actually pretty great.

 

My temp in my s4 has been going up as high as halfway, i suspect my clutch fan as well but will test to spin it by cold vs warm to see.
if i turn my heater on full it slightly lowers the temp. I just topped up on coolant and bled the system and watched the thermostat open up at operating temp so thats where im at.

 

i have the same problem. On my tII s4 at idle the temp goes to 200F (a little over halfway on da gauge)

when i drive it the gauge goes back down to 1/4 new factory motor cap and thermostat.

fan clutch spins about 1/2 way engine cold or hot. so im ordering a fan clutch asap.

 

200F idling in the middle of summer isn't that hot. The thermostat doesn't open fully until 203F (it cracks open at 180F). Your fan clutch might be ok--it's hard to say without physically examining it.

 

Basically if it's good it should turn cold but with some resistance, one mechanic described it to me as "like it's filled with peanut butter".

A symptom of a bad fan is that your temps are totally fine on the freeway (most air from car movement), but trouble at stops or very low speeds (most air from fan). It can get serious; you can overheat by stopping the car long enough on a hot day. If it's not serious but you're still not sure you could always get a cheap junkyard fan clutch (tested for peanut butter-ness) and store it in your garage until your own clutch gets worse, if ever.