| [GMCnet] Tid Bit. The stock fan clutch [message #355205] |
Fri, 29 May 2020 10:31  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
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In the GMCMI Parts Interchange Index there are 3 fan clutches listed:
Standard Duty Hayden #2705
Heavy Duty Hayden #2747
Severe Duty Hayden #2797.
As I recall, The severe duty replacement unit. Looks like the original GM unit. But is not correct for our fan size/ load according to the present day manufacturers . Some GMC owners say it's the best. Comes down to your call.
That got me thinking. What are the different situations to create a need for each one of the 3. So I went to the companies that make them. Seems that the duty. Is based on several issues.
1 The diameter of the fan.
2 Pitch of the fan blades.
3 The width of each blade.
To get them to turn on or off properly. They must have the proper rotating load. It's all about the fan specs. Nothing else. And none of these. Engine size, miles driven, coach size, and how long that they’ll last. I've gone down this road. Didn't enjoy the trip.
As a note for those that don't know what turns the fan clutch on, and off. There's a bi metal spring on the front of the clutch unit. That heat from the radiator. As it goes up, and down. Causes that bi metal spring to engage, or disengage the clutch. By way a viscus material.
We have some options. One is go to your local parts store. Or go to Applied GMC. Some may say that I must be working for Applied. No. I've just been down that rocky road of ending up with parts not working, or fitting properly.
Another good example of buying parts for our unusual GMC's, Are shock absorbers, Our rear shocks look just like many others. But ours work in a much different way. It's crazy how many GMC's that I've seen. That handled poorly . Because of having the wrong shocks installed. We have many examples of this issue on our GMC's. Do as you see fit for your comfort zone. I just want to do it once.
( Others may have a different view and those views are always welcomed.)
Bob Dunahugh
78 Royale since 2003
4 COPO Yenkos. My passion
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