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DIY Fan Clutch mod

I recently ran into something different when I did this mod on my new fan clutch. The spring and mounting was different than what I've seen in pics and what was on my old clutch. The spring was short enough that I was able to only get 1/8th" of extra length on the spring. This left only 1/8th" to engage the hub body. Not enough to get the fan to come on when towing.

With my daughters help here is a pic of what my new clutch looks like. This pic is of a Hayden clutch. The clutch I got was NAPA severe duty #TEM 271339.

In this pic you can see how short the spring tab is. The 1/8th" mod was not enough, so I did something totally different. I took the spring out of the old clutch, modified it, carefully removed the spring from the new clutch, and put the old modified spring in the new clutch. Haven't done any towing yet so only time will tell if I accomplished anything.

Don
 

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In 10F weather, a raised plow can get an empty truck to exceed 215F at 70 - 80 mph. Then the stock fan kicks in fully and pulls the temperature right down. But at 215, its a little too hot for comfort.

The blade can actually pull a vacuum between the blade and radiator. Before adding a snow deflector, I had to run the blade an inch off the ground on the Interstate to keep the temps down. The blade hit the ground on ever bump and expansion joint.


This is definitely on my list of mod's.

Thanks to GMCTD, and mfgguru for remembering the original post.

John

Finally made the fan clutch mod! Moved the bend about 3/16 toward the tip.

What a difference. Have not taken any measurements with the scanner, but when the thermostat opens, you can hear the fan kick in. Once it cools down it kicks out.

Tried carrying the plow around for a little while. Air temperature was 89F.
With the blade full up, the temp went up to about 200F. At a constant 55 to 60 mph the temp was hovered around 205 to 210. If I got on it at 60 mph, It could get the temp to spike @ 215, but with moderation of speed, it would pull back down without dropping the blade. The fan was fully engaged at all times.

Dropping the blade (about 4 ~ 6" off the ground) would get the temperature back below 200F at highway speeds.

For reference, before make the fan clutch mod:
I would have the rare instance that I had to carry the plow blade in the summer. If the blade was not 1/2" off the ground, the truck was at +215F and wanting to climb. :eek:
In winter, the blade had to be pretty low if doing any highway travel to keep the engine temps down.


The expectations are for good cooling in winter weather when needing to carry the plow blade. Should not have to worry so much about how high the blade is durring transporting.
 
Sorry to hear that Kenny. I figured I would break mine too. Especially after bending it twice, the first time I went the wrong way.

I've spent enough on that engine as it is.
 
I have a 1994 6.5 2500 sle with air....What thermostat did these trucks come with stock? My gauge reads celcius.... It always reads around 80c and takes a long time to heat up. Does GM have a 195?, (I ask this as toyota only had 1 temp for my turbo diesel) And I don't want any dumb looks from the GM parts guy here, or should I just go to Rock Island Auto?
 
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