Everything I have seen for cfm seem to be speculation w/ numbers from 2500-2900 cfm for the low side and 3200-4500 on the high side. I'm pretty sure I wired mine on the high side and I used a 70 amp relay to keep from burning up the controller and 10 gauge wiring for the power and grounds.

 

How does a clutch fan move more cfm if its speed is locked to the engine rpm? An electric fan runs at max speed all the time.

The issue here is clearly CFM. The Tarus fan isn't moving enough air on low speed. High would cure it for sure but it requires far more amperage than the cig lighter circuit is going to provide.

 

I don't care what type of fan it is, if you're doin 30mph or more you have more air going past your radiator than any fan could ever match. Is it possible that the Taurus fan/shroud might obstructing more airflow at speed than the stock set up?

 

Feel around for cold spots on the radiator while you're towing. higher load (towing) obviously creates more heat. the rad is likely plugged just enough for that to be the threshold.

 

Alright so the problem is definently a combination of the Taurus fan on low not pulling enough cfm, and even more than that, the radiator is definently plugged. I distinctly remember the air from the fan being almost hot enough to burn my hand, yet i still put my entire hand on the front of the radiator and it was only mildly warm.

Lets talk solutions since you're all a bunch of flippin geniouses and figured out the problems without even bein near the truck (either that or im just really good at explaining it :P )

I guess i'll wire up a 70 amp relay (thats what the taurus repair manual calls for on the high side) with an 80 amp fuse inline (since i already have one) and use 10 gauge wire. Battery -> fuse -> relay ->controller -> fan. is that the right order??

Whats a good way to unclog the radiator? Just a flush with some radiator cleaner stuff?

 

I don't have any experience unclogging radiators, but from what I've read a reverse flush is your best bet and if that fails then a replacement. As for the wiring here is a link to how I did mine http://www.fordmuscle.com/archives/2...cfan/index.php the wiring diagram is near the bottom of the page. Battery to fuse link to controller to relay to fan, the diagram shows 8 gauge wiring for the power and ground, I used 10 gauge car audio wiring.

 

This is one reason I haven't done the e-fan mod. It's a PIA and if it fails you will overheat and it would void any kind of warranty.
Anyways, 70amp on stock alternator is ALOT! You may want to upgrade your alternator as well. Because stock alt produces 136amp at full load and your talking about draining half that power just for a e-fan. I'd go 200amp if i ever went with an e-fan.

 

The taurus fan only draws about 40 amps on high speed.

 

I would get the radiator taken care of before changing over the wiring of the fan. Even if you put it on high you still have a problem with the rad and if it gets worse even the high speed of the fan won't keep the engine cool for you.

 

Pyro and I saw this radiator at a 4x4 show last year. If mine ever starts to go, I'm jumping on it!!!

http://www.flex-a-lite.com/auto/html..._radiator.html

Has both External AND Internal cooling fins: