Fan clutch failing?

[beanhead]

I've been seeing increased coolant temps when idling my RB engine. What I've noticed is, if I start it up after some cool-down time there is a good amount of airflow moving through the radiator; I can really feel the wind with my hand and if I drop a paper towel into the canyon between the grill and radiator it immediately sucks it against the radiator, even if I drop it against the backside of the grill. After driving, I can idle it in gear in the driveway with the E-brake on and watch the temps slowly climb. Drop a paper towel in, and it will only hold to the radiator if I drop it right against it. I can feel much weaker airflow at the front of the radiator than when it was cold.
Thing is, I shut it down and the fan turns with what I'd consider a good normal amount of resistance; if I try to spin it, it moves less than a quarter turn on it's own....but the weak air movement when hot maybe tells a different story? Can the fan clutch be bad even if it passes the 'spin test'? It's a factory 7-blade fan on a Hayden 2947. Thanks!

 

[RJRENTON]

IMO.....
Replace the Hayden clutch with a MOPAR # 2806070 repro clutch, which is a torque drive fan clutch used on the 440+6 and Hemi engine. Not inexpensive about $200 + Shipping also look at the 7 blade fan to go with the clutch. 18.5" diameter x ~ 30° pitch angle plus looks origional. I believe your Hayden clutch is a thermal drive unit. The reason everyone buys Hayden clutch is the price is considerably less but....you get what you pay for.
Available thru Tony's Parts in Delaware.
www.tonysparts.com/b-body-parts
A concours unit with a date code is also available for an additional cost.....your choice...
BOB RENTON

 

[beanhead]

IMO.....
Replace the Hayden clutch with a MOPAR # 2806070 repro clutch, which is a torque drive fan clutch used on the 440+6 and Hemi engine. Not inexpensive about $200 + Shipping also look at the 7 blade fan to go with the clutch. 18.5" diameter x ~ 30° pitch angle plus looks origional. I believe your Hayden clutch is a thermal drive unit. The reason everyone buys Hayden clutch is the price is considerably less but....you get what you pay for.
Available thru Tony's Parts in Delaware.
www.tonysparts.com/b-body-parts
A concours unit with a date code is also available for an additional cost.....your choice...
BOB RENTON

Thank you for the feedback, the only reason I use this particular Hayden I'm short on space...I'd love to use something else but I've yet to find something suitable with 3" or less overall height.

 

[RJRENTON]

Looking at the Hayden 2947 clutch, it looks as if the overall length is greater than the 2806070 clutch. If this is so, the Mopar clutch will fit. However, if you have installed a thicker aftermarket radiator, the running clearance may be an issue. You did not say in your origional query so I assumed it was a normal installation. Hayden makes fine products but I seek origionality which prompted my comment, cost not being a consideration. In addition, MOST aftermarket fan clutches use a universal, slotted mounting bolt pattern for water pump interface, which, to me, just doesn't look correct....
Does HAYDEN market a "torque drive" clutch that you could consider? Just asking....
BOB RENTON

 

[1967coronet]

beanhead, I know apples and oranges... my 18" fixed 7 blade and shroud will hold a dollar bill on the outside of my grille at 700 rpm idle.
As far as space you can use whatever length spacer you need to get it just right.
But yes I agree with you on your fan clutch giving up at higher temp.
Mabey just a replacement clutch will cure it ?
I know I give up a few hp but the old fixed fan works good for me.

 

[RJRENTON]

Thank you for the feedback, the only reason I use this particular Hayden I'm short on space...I'd love to use something else but I've yet to find something suitable with 3" or less overall height.

MEASURING the overall length of the new # 2806070 fan clutch: 3.0" from the face of the clutch to the face of the drive hub (the mating surface that bolts to the water pump). The torque drive fan clutch SHOULD fit in the space available but you should verify.
OR...take # 5's suggestion and try for a warranty replacement of your origional unit....nothing ventured...nothing gained....you just might get lucky...
BOB RENTON

 

[beanhead]

Thanks again guys. I went ahead and ordered a new Hayden unit, although the MP torque-drive clutch would be nice it would only leave me about .25" to the radiator. A little too close for comfort....I'll soon know if the current clutch truly is the cause of my inconsistent airflow troubles.
If so, then I'll add the "if the fan clutch doesn't free-wheel when you spin it, it's still good" anecdote to my Mopar mythbuster list

 

[Joe66satellite]

I have a 440 built in my 66 satellite I'm in Nevada it's hot here the car ran hot it's got headers it's a hot machine the fan clutch seemed a little wobbly so I replaced it with the Hayden 2947 after reading several post on this website I must say my cooling has not improved much

 

[beanhead]

Following up. Replaced my old 2947 fan clutch with new, same part #, bingo....airflow at a hot idle! I can feel quite an increase in the airflow rushing through the grille now, like it should be.
Moral of the story here is, just because the fan clutch has a lot of resistance when spinning by hand doesn't necessarily mean it's working properly when the engine is turning.
Thanks guys