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09-08-2011, 05:56 PM
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#21
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Winnebago Master
Join Date: Sep 2004
Location: Glen Allen, VA
Posts: 2,169
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I am aware of at least one owner of a coach with a CAT C-7 and rear rad who talked extensively with the Freightliner folks in Gaffney, SC about adding a fan clutch to his. I believe the answer was that, as has been noted, the rear radiator configuration requires the solid drive to ensure adequate cooling under all conditions.
A call to the Frieghtliner Help Line might get you an official answer.
Considering my C-6 (3126E) and how it runs, I would think the primary advantage to having a clutch would be the additional HP gained when the clutch was disengaged. However, about the only time I really need the 'grunt' is when climbing a grade or otherwise working the engine hard. That is when the clutch would engage so not sure you would see the desired gain when you need/want it most.
Maybe my thinking here is wrong but, just pondering .
__________________
'07 Country Coach Allure 470 Siskiyou Summit #31578, Cummins ISL 425; 2014 Ford F150 toad; Air Force One Toad Brake.
Glen Allen, VA; Smith Mountain Lake, VA.
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09-09-2011, 07:46 AM
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#22
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Registered User
Join Date: Oct 2009
Posts: 437
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I think Your thinking is spot on.If the posters read your post ,there question is answered;; Thanks ;; life is good
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09-09-2011, 08:58 AM
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#23
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Registered User
Join Date: Mar 2011
Posts: 48
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Believe it or not, the fan is used also to help with the exhaust brake .
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09-09-2011, 01:50 PM
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#24
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Winnie-Wise
Join Date: Jun 2010
Posts: 478
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Perry
I'm curious - how is the fan used to help the exhaust brake?
Thanks
Safe Travels
Bob
__________________
Bob, Sandi & Marmaduke the Big Pug
SW OREGON 2004 Journey 39K, 330 Cat
If towing: a 2006 Mini Cooper or 1995 Wrangler
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09-09-2011, 10:50 PM
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#25
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Winnebago Master
Join Date: Dec 2009
Location: Out there, somewhere
Posts: 1,740
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Quote:
Originally Posted by 1ciderdog
Perry
I'm curious - how is the fan used to help the exhaust brake?
Thanks
Safe Travels
Bob
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Well,
Even I think I can answer that one. Because the fan (solid drive) creates a ton of air movement while using a bit of the engines horse power to cool the radiator, it will work in reverse too. That is, if it takes horse power to run it, then it will take up some of the brakeing too because of it trying to move that much air, while the exhaust brake is on,the drive train is causing the engine to rev because the transmission is down shifting and therefore spinning the engine at higher revs which, the fan is trying to slow the the whole thing down because of the pitch of the blades.
I too see the reasoning for the load that would be placed on the engine when the fan is engaged while climbing grades etc. But, when things are normal, and you're just cruising along with outside temps at say, 60 or so degrees, and the engine is not laboring at all, then why turn that fan, if the engine is cooling adequately? I'm just trying to reason things out here.
Scott
__________________
2004 ITASCA HORIZON 36GD, 2011 GMC Sierra 1500 4x4 Toad '08 GL 1800 Gold Wing
Retired-29.5 yrs, SDFD, Ham - KI6OND
Me, Karla and the Sophie character, (mini Schnauzer)
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09-10-2011, 09:42 AM
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#26
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Registered User
Join Date: Mar 2011
Posts: 48
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The fan is turned on to put a load on the motor when engaging the engine brake.
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09-10-2011, 09:47 AM
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#27
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Winnie-Wise
Join Date: Jun 2010
Posts: 478
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Yes, the direct drive fan is a drag on the engine all the time, so exhaust brake or not it would help slow the engine & vehicle when you let off the fuel. I can see it would help with a clutch or electrically controlled fan.
Safe Travels
Bob
__________________
Bob, Sandi & Marmaduke the Big Pug
SW OREGON 2004 Journey 39K, 330 Cat
If towing: a 2006 Mini Cooper or 1995 Wrangler
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09-10-2011, 09:55 AM
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#28
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Registered User
Join Date: Mar 2011
Posts: 48
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With the Cummins you can turn the fan on or off for engine braking with the Insite software program.
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09-10-2011, 04:05 PM
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#29
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Winnie-Wise
Join Date: Jun 2010
Posts: 478
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OK Now I understand but that won't work for me or the person who started this thread since we both have Cat 330's. I like the Cat but I think if I get another somewhat newer motorhome it'll have a Cummins.
Safe Travels
Bob
__________________
Bob, Sandi & Marmaduke the Big Pug
SW OREGON 2004 Journey 39K, 330 Cat
If towing: a 2006 Mini Cooper or 1995 Wrangler
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09-12-2011, 09:42 AM
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#30
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Registered User
Join Date: Oct 2009
Posts: 437
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Just some quick. Numbers. 744 watts = 1 hp It takes appx 15 hp to turn the fan. 15 X 744 = 11160 Watts Devided by 12 V equals the amp= 930 amps. to spin the electric fan; Then you put an added load on your altinater to recharge that takes Added HP to turn; Do some figgers;; It's mind boggeling; And everyone will have a differant figer, life is good.
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09-12-2011, 01:23 PM
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#31
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Winnebago Watcher
Join Date: Feb 2010
Posts: 1
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930 amps? thats a hugh fan, I looked into electric fans a while back and 4 spal fans come in at way less then that. If i rember correctly there is room on the radiator to get around 17000cfm mounted. Not sure if 17000 would cool the rig anybody know what the stock fan is rated at?
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09-14-2011, 09:44 PM
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#32
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Winnebago Watcher
Join Date: May 2011
Posts: 3
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The reason a fan clutch is not installed is cost. I worked for Schwitzer in Indianapolis. They manufactured viscous fan drives for front radiator class 8 trucks with up to 36" diameter fan blades. It takes 40 hp to drive a 36" fan. Those drives have a bimetallic strip on the front that detects air temperature coming from the radiator and engages and disengages as needed. The newer diesels have electronics that can control the operation of an electric actuated fan clutch. I have a Journey with a C7 without a fan clutch and I'm going to install one. I want to iomprove fuel mileage and get more horsepower to the rear wheels. Schwitzer also made all the Cat turbos at the time I was there. Parts are about $800 and I'll do the work myself. But at $4/gal of diesel it makes sense to me.
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