Thermal vs. Non-thermal Fan Clutch

[1987 GMC Jimmy]

For the guys not running electric or flex fans, what are your preferences for clutches? I live where it gets dreadfully hot in the summer so I want my engine to be cooled as effectively as possible. The non-thermal's last longer and are cheaper, but if there's a good pro to the thermals that you guys find, I'd like to hear about it.

 

[GTME94]

Not sure what options are available. My Big Block comes factory with the thermal clutch. I can hear when it kicks on full blast which isn't too often even when towing.

I'd go thermal, it cools full blast when needed, reduces load when not needed. I just replaced my clutch last year, was only about $40 for the heavy duty.

 

[Rusty Nail]

Hayden brand fan clutches ONLY. They come from pep dudes roun herr.

 

[smoothandlow84]

X2 for a thermal clutch fan. Here on the surface of the sun a.k.a the VALLEY of the sun (Phoenix, Az)..summer temps can soar to 116- 120 degrees....but its a dry heat. Anyway...the clutch fan works better imo than a constant fan that sucks all the power all of the time while driving or idling. It also helps that the clutch fan allows the motor to warm up in the winter when its near freezing outside.

 

[74 Shortbed]

Thermal clutch is the only way to go..

 

[MikeB]

http://www.haydenauto.com/featured products-fan clutches and fan blades/content.aspx

Obviously, as you move from "Standard Duty Thermal" to "Truck Fan Drives", you will have an increase in noise as well as horsepower required to turn the fan.

I am using the Light Duty Thermal fan clutch in my 82 C10 with an 18" (I think) OE-type fan, an aftermarket aluminum version of the smallest radiator offered by GM, and a fan shroud. Engine is 350, trans is TH350 auto.

The coolant temp at idle stays at 190-195 degrees on 95-100 degree days, and drops to around 180-185 when the truck is moving. However, I don't tow a trailer or haul more than 1,000 lbs including passengers, and the truck does not have A/C. If I hadn't got mine for free, I probably would have bought the Heavy Duty version, which I may have to do if I ever add A/C.

One more thing: I'd strongly suggest using a water pump with 3/4" shaft instead of 5/8" if you use anything other than the Standard Duty clutch.

 

[1987 GMC Jimmy]

Very good info here. You guys have made a believer out of me because I want to have that extra power and that extra mile per gallon. I will say, however, that in reading the link Mike posted, it said the thermal clutch will last longer. I thought the non-thermal one would because, as mentioned, it's more direct and constant with the water pump shaft. The thermal one is more complex and has a good deal of RPM variability to it, which results in increased slippage as it wears out.

 

[Rusty Nail]

Wait. What if I have a flex fan screwed to my fan clutch?

That counts, right?

 

[1987 GMC Jimmy]

Yep. I meant the direct drive flex fans.