Let me see, the Bean Counter Engineered fan clutch with the plastic fan would not move as much air as the steel fan with the Bean Counter Engineered fan clutch. Further more the first fan clutches used on the '05s were worse than the '06 fan clutches as have been reported by several members. I would have to assume since I was not there, that Chrysler used the Bean Counter Engineered fan clutch in their development. Can someone verify my assumption?
For sure the fan clutch is not heavy duty. It was designed to have lower resistance when the clutch is disengaged to provide better fuel economy. The lockup curve is set high to help get the advertised EPA fuel economy rating. This ends up sacrificing clutch longevity as it undersized to begin with. Most manufacturers complete the severe duty testing with locked "on" fan clutches to avoid a clutch failure during the test process...funny! The clutch design probably works satisfactory for 70% of the CRDs doing light duty. The Hayden is for sure better for towing rigs based on comments here, not having seen or tested it. Is the Hayden unit much heavier than the stock? If it is, then the plastic fan might be a better compromise due to having less weight. The unsprung cantilevered mass should not increase much or it may affect the hub bearing life. That bearing is by no means overengineered.
Had they put their jar of ISO Approved serial numbered etched beans into the drawer which they use for counting when they designed the cooling fan/fan clutch assembly and, instead used the Hayden Heavy severe duty fan clutch, they would have gotten it right the first time.
According to the observations in this post on KJ, the plastic fan with the Hayden Severe duty fan clutch moves more air than the stock setup, having done so myself, I must agree.
http://www.jeepkj.com/forum/showthread.php?t=48653If the metal fan moves more air with the '05 fan clutch that turned out to be junk compared with the '06 fan clutch, does anyone even care?
You would only care if towing a heavy load up a 6% grade, mainly people out west. The overheat protection on the engine ends up dropping the vehicle max speed by 8-10mph if at wide open throttle for 20+ minutes. It would mean going from 46mph to 38mph.
Did the metal blades conduct more heat into the fan clutch to get it to turn on sooner?
For anyone who does care, they should mount manometers in front of the grill and in the engine compartment to check the differential pressure going up the mountain in 100F heat pulling 5000# load. Do the test under the same conditions with both the '05 fan clutch and metal fan Vs the Hayden severe duty fan clutch and plastic fan. Of course post the results for all of us to see.
I would bet the Hayden severe duty with the plastic fan will do better and the engine temp will be cooler. Use the Hayden severe duty clutch and plastic fan, you have the best of both.
The engine runs cooler because the Hayden clutch must have more drag when unlocked. This should spin the fan faster in most normal driving conditions. When the Hayden is unlocked the plastic fan will use less power than the metal fan, so that should help if using the Hayden. In unlocked states fan drag can be 1-5 hp depending on design, when locked the power can be 10-15hp or more depending on application (automotive).