Fan Clutch--Shean update

[scott shean]

As some of you know, I have been fighting "fan clutches" since early spring.

To begin with, I have a 1978 (403 CID), which may or may not, require a
different clutch than the 455 CID engines. When the original fan clutch
went out, the local GMC dealer replaced it with "something", that never did
"roar". After reading this "GMCNet", I changed to the Hayden 2797, which
"roared" continuously. I knew that this wasn't the way the original clutch
operated, so I exchanged it for the 2747, which "roared" until 45 MPH. This
also is not how the original behaved. Now I have the 2705, which doesn't
"roar" ever, even at times when the original clutch would engage. However,
the engine temp. stays right at the 1/4 mark, as it always has.

My conclusion, at this point, is that Hayden does not make a fan clutch that
matches the original. The 2797, and 2747 clutches on my engine, make a
noise that is too obnoxious for normal driving. I'll stay with the 2705
until I decide that I need more cooling, then I will pay the price for an
"original" from Cinnabar.

As to the question about the negative effect upon gas mileage, I have not
run long with the "roar", but the horsepower that must go into the fan has
to be significant, and will show up as increased gas consumption. I would
guess that it is something like the dash A/C...about 1 MPG.

Scott Shean
78 Royale
Baton Rouge, LA

 

[jim bounds1]

Scott,
I use the 2705 and have, as you found, had comparable results with the OEM.
There is a balance between noise andair moving capacity and it seems the
2705 does a good job at moving air while not driving you nuts.

How is the 2705 performing? You said the temp. needle is at the same place
as before, is that OK?

I'm interested in what you think, I have recomended many customers to use
the 2705 and all have been satisified.

Jim Bounds
- -----------------

>As some of you know, I have been fighting "fan clutches" since early spring.
>
>To begin with, I have a 1978 (403 CID), which may or may not, require a
>different clutch than the 455 CID engines. When the original fan clutch
>went out, the local GMC dealer replaced it with "something", that never did
>"roar". After reading this "GMCNet", I changed to the Hayden 2797, which
>"roared" continuously. I knew that this wasn't the way the original clutch
>operated, so I exchanged it for the 2747, which "roared" until 45 MPH. This
>also is not how the original behaved. Now I have the 2705, which doesn't
>"roar" ever, even at times when the original clutch would engage. However,
>the engine temp. stays right at the 1/4 mark, as it always has.
>
>My conclusion, at this point, is that Hayden does not make a fan clutch that
>matches the original. The 2797, and 2747 clutches on my engine, make a
>noise that is too obnoxious for normal driving. I'll stay with the 2705
>until I decide that I need more cooling, then I will pay the price for an
>"original" from Cinnabar.
>
>As to the question about the negative effect upon gas mileage, I have not
>run long with the "roar", but the horsepower that must go into the fan has
>to be significant, and will show up as increased gas consumption. I would
>guess that it is something like the dash A/C...about 1 MPG.
>
>Scott Shean
>78 Royale
>Baton Rouge, LA
>
>
>
Jim Bounds/Co-op Motor Works Orlando www.gmccoop.com