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| Fan Clutch [message #92559] |
Mon, 19 July 2010 10:39  |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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I thought I'd start a new thread on this since I hijacked another thread on this earlier. A few weeks ago, on my camping trip, I left Phoenix and my fan clutch cycled normally on my way up into the mountains. It was pushing 110F and as normal, by that time the clutch would gradually stay on full time. When I got to Globe, my coach started to overheat and I realized the fan clutch was no longer on. I was surprised that it failed so suddenly. I nursed it up to Roosevelt Lake and camped for about 10 days. On the way back, I picked up a Hayden "severe duty" 2797 and took off for Phoenix. Luckily most of that run is downhill, but the fan never came on and the coach ran hot (about 210) all the way home. At the same time, my storage neighbor mentioned that his coach runs at that temp all the time and he has never heard his fan clutch come on. I encouraged him to try a new clutch and he bought a Napa 271301. He reported that now it runs between 190 and 200 and the clutch cycles on and off during about a 100F day. So, I decided to try one of those. I quickly discovered that the Napa 271301 is identical to the Hayden 2797--in fact the box even says 2797. I was discouraged, but since I had it, I decided to swap it. Well, lo and behold, it cycles perfectly and seems to duplicate how my original Delco operated. I can only conclude that buying a Hayden is a crap shoot when it comes to calibration. I returned the 2797 I bought in Globe at the local Checker--no questions asked. Interestingly, these models are made in the USA if that makes any difference. I had toyed with ordering a Delco, but suspected I may have wound up with a Hayden anyway. Sorry for the long post, but for now I'm satisfied with what I have, but it sure isn't very comforting for anyone who needs a new clutch. BTW Steve, thanks again for your great writeup on the Western States site.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Fan Clutch [message #92563 is a reply to message #92559] |
Mon, 19 July 2010 11:44  |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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This is good Bob. Perhaps this means that maybe the NAPA specs call
for the made in USA version of the 2797. I know for certain that the
Torque-flow version of the 2797 (Autozone) is made overseas.
Keep us updated on any longevity issues.
Do you have any recollection of what your coolant temps were when the
fan engaged and disengages? (Old one.) And the same for the new 2797?
Thanks Bob.
On Mon, Jul 19, 2010 at 8:39 AM, Bob de Kruyff <NEXT2POOL@aol.com> wrote:
>
>
> I thought I'd start a new thread on this since I hijacked another thread on this earlier. A few weeks ago, on my camping trip, I left Phoenix and my fan clutch cycled normally on my way up into the mountains. It was pushing 110F and as normal, by that time the clutch would gradually stay on full time. When I got to Globe, my coach started to overheat and I realized the fan clutch was no longer on. I was surprised that it failed so suddenly. I nursed it up to Roosevelt Lake and camped for about 10 days. On the way back, I picked up a Hayden "severe duty" 2797 and took off for Phoenix. Luckily most of that run is downhill, but the fan never came on and the coach ran hot (about 210) all the way home. At the same time, my storage neighbor mentioned that his coach runs at that temp all the time and he has never heard his fan clutch come on. I encouraged him to try a new clutch and he bought a Napa 271301. He reported that now it runs between 190 and 200 and the clutch cycles on an
> d off during about a 100F day. So, I decided to try one of those. I quickly discovered that the Napa 271301 is identical to the Hayden 2797--in fact the box even says 2797. I was discouraged, but since I had it, I decided to swap it. Well, lo and behold, it cycles perfectly and seems to duplicate how my original Delco operated. I can only conclude that buying a Hayden is a crap shoot when it comes to calibration. I returned the 2797 I bought in Globe at the local Checker--no questions asked. Interestingly, these models are made in the USA if that makes any difference. I had toyed with ordering a Delco, but suspected I may have wound up with a Hayden anyway. Sorry for the long post, but for now I'm satisfied with what I have, but it sure isn't very comforting for anyone who needs a new clutch. BTW Steve, thanks again for your great writeup on the Western States site.
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: [GMCnet] Fan Clutch [message #92573 is a reply to message #92563] |
Mon, 19 July 2010 12:05 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""This is good Bob. Perhaps this means that maybe the NAPA specs call
for the made in USA version of the 2797. I know for certain that the
Torque-flow version of the 2797 (Autozone) is made overseas.
Keep us updated on any longevity issues.
Do you have any recollection of what your coolant temps were when the
fan engaged and disengages? (Old one.) And the same for the new 2797?
Thanks Bob.""
Yes the longevity issue is a big if. The Hayden 2797 that I purchased at Checker in Globe was also made in the USA--totally identical part. My original and replacement seem to come on at about 195-200 and off at about 190-195 give or take a couple of degrees. The clutch doesn't quite react exactly as my temp gage and I'm assuming it's due to inertia. In the past I never really looked at the gage and felt the clutch cycling was a better indicator.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Fan Clutch [message #92624 is a reply to message #92579] |
Mon, 19 July 2010 21:38 |
shawnee
Messages: 422
Registered: February 2004
Location: NC
Karma: 0
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Senior Member |
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| emerystora wrote on Mon, 19 July 2010 14:00 |
On Jul 19, 2010, at 11:05 AM, Bob de Kruyff wrote:
> The clutch doesn't quite react exactly as my temp gage and I'm assuming it's due to inertia. In the past I never really looked at the gage and felt the clutch cycling was a better indicator.
>
> --
> Bob de Kruyff
> 78 Eleganza
> Chandler, AZ
The clutch will never react exactly as the temp gauge because the temp gauge is measuring the temp of the coolant in the block while the fan clutch reacts to the temperature of the air moving through the radiator and this will change as the ambient air temp changes while the temp in the block doesn't change as much with the ambient temp as the thermostat keeps the block temp pretty much in a narrow band.
Emery Stora
77 Kingsley
Santa Fe, NM
__
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Emery,
Don't forget the effect of the dash air conditioner on more heat going to the fan clutch when it is also on. It is added to the ambient air temperature going through the radiator. Also the effect of sunshine on the black top or cement will increase the ambient air temperature and effect the fan clutch.
Gene Dotson
74 Canyonlands
www.bdub.net/Motorhome_Enhancements New Windows and Aluminum Radiators
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| Re: [GMCnet] Fan Clutch [message #92650 is a reply to message #92624] |
Tue, 20 July 2010 07:20 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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Easy guys. I specifically stated "coolant temperature" when I asked
the question. I have tested quite a few fan clutches in my GMC with a
temp probe mounted inside the shroud so I could monitor the temp of
the air that comes through the radiator. I never made a test run with
the AC off as it provides as much heat soak as possible and in a GMC,
it is the norm. In every test, air temp inside the shroud followed
the pattern of the thermostat opening and closing at specific coolant
temps. Regardless of the outside ambient air temps, I can watch my
temp gauge and tell you within a minute when my fan clutch will
engage. Very consistant operation.
Another value that I found consistant was the fact that the fan
clutch remained engaged until the coolant temp dropped below the
thermostat value. These values repeated themselves regardless of
which fan clutch I was testing.
On Mon, Jul 19, 2010 at 7:38 PM, Gene Dotson <shawnee@charter.net> wrote:
>
>
> emerystora wrote on Mon, 19 July 2010 14:00
>> On Jul 19, 2010, at 11:05 AM, Bob de Kruyff wrote:
>>
>> > The clutch doesn't quite react exactly as my temp gage and I'm assuming it's due to inertia. In the past I never really looked at the gage and felt the clutch cycling was a better indicator.
>> >
>> > --
>> > Bob de Kruyff
>> > 78 Eleganza
>> > Chandler, AZ
>>
>> The clutch will never react exactly as the temp gauge because the temp gauge is measuring the temp of the coolant in the block while the fan clutch reacts to the temperature of the air moving through the radiator and this will change as the ambient air temp changes while the temp in the block doesn't change as much with the ambient temp as the thermostat keeps the block temp pretty much in a narrow band.
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>> __
>
>
> Emery,
>
> Don't forget the effect of the dash air conditioner on more heat going to the fan clutch when it is also on. It is added to the ambient air temperature going through the radiator. Also the effect of sunshine on the black top or cement will increase the ambient air temperature and effect the fan clutch.
> --
> Gene Dotson
> 74 Canyonlands
> www.bdub.net/Motorhome_Enhancements New Windows and Aluminum Radiators
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
_______________________________________________
GMCnet mailing list
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