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Re: [GMCnet] Fan Clutch [message #61280 is a reply to message #61249] Fri, 23 October 2009 09:28 Go to previous messageGo to previous message
Tin Gerbil is currently offline  Tin Gerbil   United States
Messages: 236
Registered: October 2006
Location: Vancouver Island, B.C.
Karma:
Senior Member
My great, great, great grandfather was;
http://en.wikipedia.org/wiki/Don_Quixote
Gordon

Ken Burton wrote:
>
> Tin Gerbil wrote on Fri, 23 October 2009 00:44
>> Ray;
>> I have a 185*F thermostat.
>>
>> You have just reiterated my point. Your old light duty fan clutch was
>> perfectly adequate for the job of cooling your engine. It was working
>> fine, until it failed. Now you have replaced it with a 4644 which is
>> not "kicking in all the time." It is kicking in at the exact same
>> temperature as the old one. The noise is generated because it is
>> coupling at it's correct ratio, of 90% of engine rpm. This is the
>> meaning of Heavy Duty. It has nothing to do with the expected life span
>> of your new fan clutch. Your old one was coupling at it's design ratio
>> of only 65% of engine rpm, therefore it made much less noise. You have
>> increased the ability of your cooling system far beyond it's needs, as
>> you state, "my engine always ran cool". Now you will burn more gas and
>> enjoy the knowledge you lacked before, that the fan was working, because
>> now you can hear it. You get to hear the extra $50 you spent on a Heavy
>> Duty Fan Clutch.
>> I stumbled upon this truth because I purchased two new 1 ton Ford diesel
>> trucks in 1987. One had the "wrong fan clutch" (according to Ford) and
>> was very quiet. One had the "correct fan clutch" and drove me nuts. I
>> replaced the noisy one with another "wrong" one and never experienced a
>> cooling problem while punishing these little trucks with 6000 pound
>> loads on very steep winding roads for many 100,000 miles. These little
>> trucks were the standard rig in a niche market of small loads of fresh
>> fish, that had to get quickly to market. My fuel mileage was so
>> consistently better than the other fellows who had identical trucks,
>> that they ignored my claims. We spent several hours per day together on
>> ferries and with nothing much to talk about, often compared our
>> operating costs. I could save my lunch money each day, in fuel cost,
>> but never let on how.
>> Gordon
>
> You are preaching to the deaf. You are not going to convert the "if it does not make a lot of noise it is not working" crowd. What you need is some numbers like how many horse power it takes to to run each of these fans.
>
> Too bad Steve did not have a more powerful and faster motor to so he could have spun his fans at normal engine cruise speed. Then he could have also measured the AC current draw on each fan. Those numbers might have gotten some of the crowd's attention.
>
> I also wish he had tested the OEM equivalent fan which is the 15-4208. That is the one he should have had for a base line to compare the others to. Unfortunately no one provided one of them for him to test.
>
> I'm not faulting Steve for what he did. I just want more and I'm too lazy to do it myself.
>
> My take on fans and clutches is they are a standby device that should only come into play in a rare circumstance when the cooling system can not handle the heat load. I suggest that that GMC cooling system should handle the heat load over 95% of the time. In the rare circumstance, like stop and go traffic with AC on in 95 degree weather, or a long hard pull up a mountain, should the fan come out of standby mode and give some additional assistance.
>
> What we are really discussing is how much additional assistance do we need. It is my contention that the OEM equivalent is sufficient and I also prefer not to hear it working.
>
> I had the 3 of the Heavy Duty Hayden's and one standard duty Hayden. I also had the AC Delco 15-4644. After talking to Danny Allen and later to an AC Delco engineer, I settled on the standard duty 15-4208 on that AC Delco recommended as equivalent to OEM. It works and it is almost silent. I also have never needed to replace a fan belt.
>
> Good luck on your crusade. I do not think the right people are listening.
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Gordon '74 Canyon Lands "Tin Gerbil" Vancouver Island, B.C.

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