Of course he's right, He's trying to sell you something. If the fan doesn't matter why would he try to sell the combo.
Buddys right, and others have said the same thing, that's why I dmaxed and modded my clutch and have been trouble free since. I even had to back off a little on the clutch mod because the dmax fan was way more effecient than the stock steel one.
From what I understand the kennedy clutch comes on to soon and stays on to long.
This is exactly the design limit of the viscus clutch. Let me explain it better.
Slap your foot to the floor and hold it there. Because you are on a hill with a trailer and an underpowered engine to do the job. Even a Duramax will heat up doing this but will be closer to the speed limit.
The foot on the floor is going to start to heat things up. There is a time it takes for the thermostat to open if not already and radiator to heat up. Then the big delay - the thermal spring on the fan has to heat up. After it has heated up fluid has to move in the fan clutch to the working chamber to lock the fan in.
The above outlined delays mean your temperature gauge is going to move quickly to and over the 215 mark without the fan locked in. Engine is generating maximum heating to the coolant and the fan is not on so everything stores the heat in the form of getting hotter. When the fan locks in the temperature rise will slow and hopefully stop. At full load it is not likely to go down much because everything has a bunch of stored heat to get rid of now from the time working hard without the fan being on.
To only ways to get around this spring heating delay is a Electro Viscus fan clutch where the obsolete thermal spring is replaced with a electronic control OR go with a temperature set on - off Horton type of clutch. This allows the fan to lock in "wham - now" when the engine gets hot rather than having to wait for a spring to warm up. The Elecro viscus clutch computer programming from GM follows the same MPG and less customer fan noise GM philosophy and makes me suffer in AZ due to poor AC performance. Thus, I have to reprogram the EV clutch on my Trailblazer to come on sooner if I want cold AC when it gets over 105 outside degrees. The engine will run at 230 ECT degrees out here - not good on 91 octane with 10-1 compression, gasser. Dodge on their diesels offers the EV clutch design to keep the temperature under control better than the obsolete, less complicated and cheaper spring thermal clutch design. Duramax was supposed to go to this but a Bankrupt GM eliminated the clutches from the Trailblazers in 2008 and did not equip the Duramaxes with them. Bean counters at their best. :thumbsup:
The sooner you start to bring on the fan the lower the max temperature will reach because you have the fan working at a lower temperature. Trade off is it will cool things down to it's kick off point before unlocking.
Ask Missy, there is a post on here from the last discussion on fans. The factory fan comes on too late for the head crack temperature red line of the 6.5 at 215. But because customers complained about the fan noise and I maintain for increased MPG GM raised the temperature of the fan clutch to keep it off as much as possible. Sadly the 6.5 is not an engine that likes the higher temperatures and likes to crack stuff.
My experience with the Kennedy clutch is that it tended to lock in fully and then kick out. Course this was while fully loaded. It would hit 215 max if I hit a minor hill at 65. It was usually full on before the 215 mark and kept me under it no matter what I did to it. 62 MPH flat out or 33 MPH flat out, 14 PSI boost, high altitude, dry air, extra fuel, and over 105 outside air temps.
I loved to hear the fan run because when the dead factory one did not work I got to see the crankcase through a hole in a scuffed piston after head removal due to overheating the 6.5.
The airflow through the radiator on our body style is a problem. We don't get enough due to the aerodynamics designed to get us the best unloaded MPG of the big three. To improve airflow heavily loaded you need to hear the fan run. Dodge gets the same 'poor' MPG loaded or not due to wasted airflow through the engine compartment when not needed.
So Mr. Kennedy is not so much just selling you something. He is selling you something that does what is advertised to keep your engine cool by shifting the kick on temperature lower and away from the critical 215 mark. Mainly, if you ask Missy, he has a reverse rotation 6.2 clutch with the old school set point.
I imagine Heath's system works well, but, I have not used it in the extreme dessert hot environment I have here. The balance flow issue the newest water pump solves is something to look into. Price being a factor is why I have the above experience and not with Heath...
