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John Biwersi's new direct replacement fan [message #268772]

Sat, 03 January 2015 10:19

kerry pinkerton

Messages: 2565
Registered: July 2012
Location: Harvest, Al

Karma: 15

Senior Member

Here is a synopsis of the presentation John gave at Chippewa Falls.

John Biwersi has helped develop a balanced 8 blade reinforced composite fan that is quieter and pulls more air. He utilized data that Steve Ferguson did regarding fan clutches and their engaged and disengaged speed in order to make a recommendation for the proper fan clutch for this new fan. The new fan is some type of plastic like you see on new diesels. I think it has 8 blades. The hub is drilled for our clutches and is balanced. Moves more air and is quieter according to the manufacturer. Also according to the manufacturer (if I recall correctly) the new fan takes less power to turn even while moving more air. The price is slightly AROUND $120 if I recall correctly but don't hold me to it. I got one from him at the Chippewa Falls GMCMI rally.

John is a member here. I don't want to post his info but if anyone wants it, PM or email me.

John uses the severe duty clutch on his coach with a stock radiator but just after I ordered my new severe duty clutch, Bob Dunahugh posted this:

Quote:

I was having problems with 2 new Hayden severe duty clutch's not disengaging my engine fan. That's the one that is suggested in our parts book. I've never had problems with their products. And why was there a standard duty, heavy duty, and a severe duty listed in our parts book. The stock GMC fan has 7 blades, and a 2.25 inch pitch. It rotates at a fixed ratio to the crankshaft. So the clutch load is constant to the crank speed. The clutch has 2 operating conditions. Engaged. Or disengaged. Nothing else. And the engaged operation is based on the temperature of the air coming from the radiator to the coil spring on the front side of the unit. This spring tells the clutch what needs to be done for proper engine cooling. So back to my question.

What can the severe duty do the the heavy duty can't. As the unit just turns the fan blade on, or off. Duty cycle shouldn't be the issue. It's a fluid type clutch. And, these units just don't turn on, or off that off ton in our type of service. In my mind. I was missing something. So I called Hayden.

What I found out was that for our size, and number of blades. It goes like this. A 2.00 inch pitch blade would require their standard duty unit. A 2.25 inch pitch blade requires their heavy duty unit. And the 2.50 inch pitch would require their sever duty unit. He stated that if you put a sever duty unit on the 2.25 pitch blade that we have. ( Remember. That sever duty unit was designed for the load of the 2.5 inch pitch blade. ) The sever duty clutch unit can encounter problems having enough load to properly disengage. So to have the fan pull more air. Go to a 2.5 inch pitch blade . And then use the sever duty clutch unit. In short. The heavy duty unit should be use for our fan blades that have the 2.25 inch pitch fan. No others.

Given this info and the fact that my aluminum radiator is more efficient than stock AND my oil cooler is not in the radiator (thereby decreasing the heat load) I ordered and installed a standard duty clutch and installed it with the new fan blade. I'll keep the severe duty clutch for a while just in case.

My clutch was a severe duty unit that would be engaged most the time and when it did release it was still loud. The new standard unit engages when the coach first starts and disengages shortly after the temperature gauge starts to come up. So far, it has not needed to come on again. Perhaps it will on the trip. My temperature stays rock solid at 180 degrees. It is MUCH, MUCH quieter. I can actually hear the fan on my aftermarket oil cooler cycle on and off as needed. I never could before.

I was planning on waiting until I had the upcoming trip to LazyDays on the coach before I posted but the above is what I know now. I'll post more info when we get back from the rally.

Kerry Pinkerton - North Alabama Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L

[Updated on: Sat, 03 January 2015 16:52]