I'm still gonna argue....every big rig has a way of disengaging the fan and I've got to think there's a reason for that---less HP drag when the extra cooling isn't needed, but kicks in when temps go up. I'm not saying the factory clutch is the solution, but I've heard them kick in on other trucks (don't work mine hard enough to kick it in) and they really do sound like the big rigs and seem to get the job done...JMO

 

I still question the NAPA t-stat. Reason being, I have had not so great luck with NAPA stuff in the past- they are no better than AutoZone, Checker, O'Reilley's, or any other. Plus, I never can get a brand name on the stuff; t just says NAPA.

I have towed with a GCVW of 22-24K regularly and never had any overheating issues with the truck at the time. My slopes were in the 4-7% range, but I was also at 6-7000ft elevation. 9-11% for 5-10 mi will make an empty big rig get hot. How many RPMs are you turning going up the hills? What are your EGTs like? I'm not saying to keep the factory fan clutch (factory is another term for a compromise between performace and cost), but check out all possibilities. The direct fan may not cure your problem.

Daniel

 

Still never said whether or not he was basing ALL this on the POS factory temp gauge.

 

I had an over heating problem with a 3208 Cat. Replaced the t-stat's several times with new NAPA stats and had the same problem. I finally broke down and paid the extra cash for Cat parts and the problem went away. It may be worth buying a Cummins thermostat before you do the solid fan thing.

 

To simplify this, yes the T-stat may not be the best in the world and the temp gauge isn't very acurate, but when the fan actually runs I have NO cooling problems even going by the factory guage, but the times that it takes an extra minute or two to kick in is when I have heat troubles. I pull these hills 4-5 times a week and the temp rises realativley the same thus the fan should kick in around the same place if no variables are changed, which is why I am set on the fan being the problem since it is the only thing changing causing the problem. I know to alot of people that losing some HP by a solid fan running all the time is a big thing, but I am looking at saving life of my engine by not letting it overheat and being able to keep the loud pedal mashed.


Chris

 

Horton makes an electromagnetic fan clutch. It's a "will fit" but it can be done. not exactly cheap though.

 

How much is "not exactly cheap", and do ya have a link?


Chris

 

I think they're like 8-900 bucks. I'll look for a source...

 

http://www.hortoninc.com/catalog/fan...&units=english

 

The Cummins T-stat has a "stop" on it that the NAPA doesn't have. It allows the T-Stat to "partialy" open, then open completely once at operating temps. The stop also keeps the T-Stat open enough to keep the engine in its designed operating range once warm.
I just talked to Cummins this morning( buying the update T-stat kit # 3802968 today) and received that explanation.

But from what the guy said, I cant think of what the difference would be between a 180* NAPA T-stat and the Cummins one once the truck was at operating temp... except that the Cummins one would not completely close as the temps cycled, guess that would keep the block cooler...