bad fan clutch ?

[lime 70]

 I can't believe I am getting a bunch of bad fan clutches. Every fan cluch I have tried does not engage it seems the spring in the front does not get hot enough. So I started my car up and I ran it at 2000 rpm and watched the temp guage when it reached a bit over 200 degrees i shut it down and removed the fan a saw that the spring did not turn so i took a heat gun and heated up the spring and saw it move. I then reinstalled the fan on the hot engine and started it up and ran it at 2000 rpm and instantly notice a dramatic increase in fan speed until the motor cooled and fan speed dropped. I was at a friend of mines house and we were working on his cuda and I noticed it did not take much for his fan cluch to come in. I have tried a couple of cluches and the same thing happened could this be bad springs on the clutches an air flow problem I don't know I am just wondering why every Clutch i have tried does not work. My cooling system is in good working order because with a direct drive fan my engine runs at the thermostat temp. Hope fully someone has any sugestions because I really want to use a clutched fan.

[JS29U]

  I bought a brand new 84 gmc hd p/u. At 100,000 miles the clutch fan died and ran hotter. I installed a hd clutch fan, cooled good, but anything over 4 grand the fan belt screeched  really loud cause  the fan clutch grabbed so hard when it engaged.

  In 1975, my org. challenger (62000) clutch fan broke at 6 grand and lost 4 tubes on the radiator.

  The big flex fans sound like bus fans.

[Topcat]

Buy one at the auto parts place for now.

If you want an OEM one, your best bet is to send it in here. He's the only one I have heard with positive referral.

http://www.gate.net/~foliva/clutch.htm

But you won't get it back for a year. I sent mine in last February.

[lime 70]

The one I got now are the flex-a-lite clutches I get some response from them the one I got from auto zone did not work at all.

[422STROKER]

I got the HD one from Autozone and seems to work fine.   I think the HD ones use silicone fluid to couple the drive vs the bi-metallic spring.  I could be mistaken though.

Tom

[Mopar73340]

I had to use the HD unit also as the standard duty ones would not spin the fan fast enough. Now sits right at the Thoermstat temp. What type of fan are you using? I'm running a 7 blade fan and I think there is to much weight and resistance using the standard unit to spin it fast enough. Probably work ok with the 5 blade.

[lime 70]

I am using a seven blade fan for some reason I do not think I am getting enough heat on the spring to engage the clutch. I ran the car and mytemp guage showed over 200 degrees and the spring did not even move yet. And I have a standard and heavy duty clutch and they both do the same thing. I measured between the radiator and spring on my truck and durango and they are the same as my Challenger so is the spring bad or just not calibrated right

[Mopar73340]

Does your car run cool at highway speeds? If not it is another problem and not the clutch. My HD clutch unit spins the fan to a roar at startup. Maybe you have a bad one???

[hooD]

My original 1973 fan clutch died on me last summer, it began to leak fluid. 

Went to Autozone, they had one in stock, put it on and it has worked fine. 

I have a 7 blade fan.  No squealing, temp guage is OK, everything is good.

good luck.