Fan Upgrade

[BobQ]

I have completed swapping in the rare GM 7-blade fan in my '83 K2500 in place of the original 5-blade unit. I was lucky and found this 7-blade fan a couple of months ago in a local junkyard on an '82 C20 with the original red engine.

I ran into a slight hiccup when installing it; the bolt pattern of the fan clutch to the water pump is larger than the one on the old 5-blade clutch. The 7-blade clutch has a 2 1/2" center-to-center 4-hole pattern and the 5-blade clutch has about a 2 1/8" center-to-center 4-hole pattern. Luckily, the original water pump hub has both patterns already in it so it was just a matter of moving the studs to the different holes and drilling the pulley to match the larger pattern. This new fan clears the fan shroud just fine too.

I put a new Hayden Severe Duty #2828 fan clutch on it also.

I've only been able to drive it a few miles so far with the new fan, but I seem to notice the fan roar. Nothing too bad.

The weather has cooled down here so I can't really test how much it will help in keeping the engine temps down under heavy loads.

I'll get some pics of the comparison between the two fans.