Standard or Severe Duty Fan Clutch?

[JimRummy]

Im looking to replace my fan blade and clutch when I do my waterpump soon, and just wanted some thoughts on what provides the most cooling without sacrificing power. I know its usually a trade off, but im looking at hopefully something like -10% HP + 25% more efficient cooling, not -20% HP + 15% better cooling.
I know the AT runs a lot hotter, so I'd like a heavy duty clutch & blade, but it seems like its either Standard Duty or Severe Duty. I very rarely tow so severe duty feels like over kill, but standard sounds weak..
whatchu guys think?
Thanks,
James

 

[bmerr98]

If you aren't towing then you're probably doing pretty standard stuff with your truck. You could look at those flex fans that pull hard at lower RPMS and flatten out when engine speed increases. Ever considered a dual core radiator? I think some Explorers have them.

 

[RonD]

Electric fan conversion would be best.
Better low speed cooling and you get the extra horse power from not having a belt driven fan.

But standard duty would seem to fit your needs

 

[JimRummy]

Ok, thats what I was thinking. I already have the 2 row radiator, and I was just curious about the severe duty clutch & blade because its had overheating issues since day 1. Seems like I can only get about 2 years (and only maybe 8k miles or so) before the thermostat takes a dump.
So what about the fan blade itself? Ive noticed that the severe duty fan blade has 1 more blade then the standard.. Would I have to do a severe duty clutch if I got the severe duty blade?

 

[RonD]

If new blade fits clutch then it will be fine.

Fan clutch works by radiator heat, as rad temp heats up it will heat the bi-metal spring on the front of the clutch causing it to engage more.
For this to work correctly fan shroud must be in place and central rad tubes must be passing coolant so they heat up and then heat up the spring.

I have a '94 4.0l, only time I had an off and on overheating issue was when the heater core was getting older and starting to clog up.
Seems on the '94 model the heater core is the by-pass system for the coolant so coolant needs to flow thru it all the time, if flow is "iffy" then odd overheating occurs.
Not sure if the '93 used the same design.
Nice thing is a new core is $28 and very easy to replace on that year, 4 screws.