You need 05+ efans and they will work awsome. LS1 fans ona 32" radiator with a half assed shroud do not work as good. Get the maching 34" radiator and fans from an 05+ and you wont have any problems. IMO

 

what size radiator would a 03 with a 5.3L have?

 

this is probably a silly question, say your truck had factory e-fans, could you do a little trimming to a stock fan shroud and run e-fans and a clutch fan? would there be anything to gain? or would the e-fans choke the radiator from the clutch fan.

 

How many of you with overheating problems have a low temp thermostat? I had all kinds of overheating problems with both a 160 and 180 t-stat, both with a clutch fan and e-fans. As soon as I put a stock one back in there all the problems are gone.

To the OP - I have towed 6000 lbs up a good grade for 2 miles at 5 psi boost on my 408 with the e-fans running on high and a/c blasting, 100* outside and never got over 214.

 

ih ya, i have pulled the grade many times, i usually don't slow to les thatn 45 mph. i was thinking that the added hp to the tires would help lay off the throtle some too helping to keep the engine temps down...

in another note, flex a lite even makes an electric fan kit for diesel trucks so i assume they could keep a gas motor cool...

Anyone know what cfm a clutch fan pulls?

 

Well if you did it right, the e-fans would have a shroud that covers the entire backside of the radiator. So in a word, no, the clutch fan would be useless.

 

28" core on an 03 with the 5.3

That's interesting, I've had great luck with both my old 180* stat and my current 160* stat (knock on wood), although I've never towed anything. I wonder if it has to do with the inconsistency of the temps of a cooler stat (something that I've noticed with the cooler stats and the factory clutch fan, while observing coolant temp with a scan tool), or if the aftermarket cooler stats are of inferior quality

I was going to recommend that the OP get the larger 05+ efans,which will fit his radiator perfectly, a 160* stat, and set the fans to come on around 177* and off at say 170* to assure a consistent, cool, coolant temperature. It should help with trans temps also, which btw I would get a big trans cooler for considering the towing.

If you put the clutch fan back on and your overheating is cured, then I'd go after diagnosing an efan problem instead of eliminating them all together. Could be a number of things wrong with them if they're the problem (wiring, bad fan motor, coming on at too warm of a temp, etc.) If the clutch fan doesn't cure the problem, time to start looking for problems elsewhere...make sure coolant is full and there is no air pockets, make sure that there isn't any junk on the fins of the radiator or a/c condenser that's blocking airflow, bad t-stat, blockage to flow, etc etc...

 

Bud is giving you VERY good advice here. I would recommend the same thing.

If e-fans are working correctly, they SHOULD be more efficient than a clutch-fan.

 

I would NOT do a low temp t-stat for towing. The cooling systems in these trucks are designed to run between about 195 and 215 from what I've seen, and generally like to stay right around 200. If you put a lower temp t-stat in, it will open fully and pretty much stay completely open. I believe the problem that I was having (and I would imagine that others would too) is that the coolant was not staying in the radiator long enough to cool down because the t-stat was wide open.

 

Hmmm, good theory but it's debatable. I think that the body of the t-stat is enough of a restriction to slow the coolant flow down so that it's in the radiator long enough to be properly cooled off. But, the factory stat did cure your overheating problems so it's kinda tough to argue with the results