The shaft size of the water pump is really the inner race diameter of the water
pump bearing. Trading down to a 5/8 size will give you a much weaker bearing
system. If you have a 3/4 shaft, find a fan clutch that will fit it.
Clark Searle
78 Kingsley
Mt. Pleasant, MI
> Gary Miller
> The 2797 does indeed have a 5/8" hole for a 5/8" shaft that normally are
> installed in our GMCs. I believe a 3/4" hole is available for other
> installations with the number 2798 (check before purchase). Also the
> 2707 is extremely marginal for use here in the West where heat &
> mountains climbs require all the help you can get, The OEM 455 fan
> clutches were similar to the 2707 and not that good.
> The 2797 has serves many of us West Coast GMCer well. The 2749
> (universal hole pattern & center insert for both 5/8" & 3/4" was
> discontinued & replaced by several clutches that were fitted to single
> purpose applications. 2797 being the one need for the GMC.
> The 2747 was the best known, prior to finding the 2749 (now replaced by
> the 2797 for our application).
> If i found a need for a 3/4" hole in the fan clutch, I would look very
> close to what Water Pump is installed. Sounds like time for waters pump
> replacement & then a 2797 fan clutch. The fan clutch is one of the most
> important items for proper cooling & they do wear out. If you don't hear
> it then it may be time for replacement. Hayden caries a Lifetime
> Warranty. I am on my third unit (under warrenty) in 100k miles. They
> last about 40-50k miles before wear out.
> The talk about needing the cast iron water pump impeller is very
> questionable to be polite. I have & many others here on the west coast
> run TRW &/or AirTek Water Pumps (with a stamped impeller) w/o any concern
> or ill effects.
>
> Duane Simmons
>
> ___________________________________________________________________
> You don't need to buy Internet access to use free Internet e-mail.
> Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
> or call Juno at (800) 654-JUNO [654-5866]
pump bearing. Trading down to a 5/8 size will give you a much weaker bearing
system. If you have a 3/4 shaft, find a fan clutch that will fit it.
Clark Searle
78 Kingsley
Mt. Pleasant, MI
> Gary Miller
> The 2797 does indeed have a 5/8" hole for a 5/8" shaft that normally are
> installed in our GMCs. I believe a 3/4" hole is available for other
> installations with the number 2798 (check before purchase). Also the
> 2707 is extremely marginal for use here in the West where heat &
> mountains climbs require all the help you can get, The OEM 455 fan
> clutches were similar to the 2707 and not that good.
> The 2797 has serves many of us West Coast GMCer well. The 2749
> (universal hole pattern & center insert for both 5/8" & 3/4" was
> discontinued & replaced by several clutches that were fitted to single
> purpose applications. 2797 being the one need for the GMC.
> The 2747 was the best known, prior to finding the 2749 (now replaced by
> the 2797 for our application).
> If i found a need for a 3/4" hole in the fan clutch, I would look very
> close to what Water Pump is installed. Sounds like time for waters pump
> replacement & then a 2797 fan clutch. The fan clutch is one of the most
> important items for proper cooling & they do wear out. If you don't hear
> it then it may be time for replacement. Hayden caries a Lifetime
> Warranty. I am on my third unit (under warrenty) in 100k miles. They
> last about 40-50k miles before wear out.
> The talk about needing the cast iron water pump impeller is very
> questionable to be polite. I have & many others here on the west coast
> run TRW &/or AirTek Water Pumps (with a stamped impeller) w/o any concern
> or ill effects.
>
> Duane Simmons
>
> ___________________________________________________________________
> You don't need to buy Internet access to use free Internet e-mail.
> Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
> or call Juno at (800) 654-JUNO [654-5866]
