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Re: [GMCnet] Fan Clutch [message #61417 is a reply to message #61398]

Sat, 24 October 2009 02:38

Rick Denney

Messages: 430
Registered: January 2004

Karma:

Senior Member

Ken Burton writes...

> It squares with me. I never see the temp gauge move once it has
> warmed up. You gauge is probably more sensitive than mine. I also
> seldom hear my fan kick in. Granted I have very poor hearing. I
> can hear it in the morning when I first start out up to 15 or 20 mph.

I never could hear the 4208 even in the morning. Even with the engine
hatch open. And I'm not dang-near deaf like you are.

Yes, my gauge is a mechanical Autometer temp gauge with a 270-degree
dial, so I can read down to the degree with precision and (I assume)
accuracy. And I would expect its response time to temperatur changes
to be measured in the single digits of seconds, with little or no
damping beyond that.

> If you have cooling problems with that aluminum radiator on a 23
> foot coach, I would be looking for the over heat or lack of cooling
> problem. Things like weak pump, air flow restrictions, or timing
> issues come to mind. Putting on a larger capacity fan just masks the real issue.

You live in flat land. The engine heats up when I climb hills at 55-65
mph. (My "hills" often have 6%, and occasionally 8%, grades.) It cools
down on the other side. There is nothing wrong with my cooling
system--new everything, right down to the recovery tank.

And if there are air-flow restrictions, they were put there by GMC.

But the results of my testing, in my mind, PROVE that there are
air-flow restrictions, and NOT cooling system problems. Engine warms
up under ram air. Fan kicks in. Engine IMMEDIATELY cools 10-15 degrees
with 20-30 seconds. Fan clutch disengages. By that time, I'm to the
next hill and the process repeats. Running the dash air, which dumps
heat in front of the radiator, increases this cycling.

If the fan can reduce coolant temperature that much in under half a
minute, then there's nothing wrong with the cooling system. If the
cooling system was inadequate, the fan wouldn't help that effectively.

But a fan should not normally be able to increase the air flow
usefully when driving at 65mph. We know that it does, because of the
effect it has on coolant temps. The only possible conclusion I can
think of is that a pressure bubble forms in the engine compartment,
preventing unaided air flow from flushing the compartment out. And the
fan, with enough power behind it, forces that pressure bubble to be
flushed out by creating a still higher pressure.

We have always contended that a cooling problem should be addressed
first, and I've done that. And I've instrumented the engine temp well
enough to know what effect the fan has on it. I think I've shown
pretty conclusively that even a top-notch cooling system will show
temperature cycling that is controlled with a positive and power fan
drive. I may have shown why it is that Gene hasn't been able to come
up with an electric-fan arrangement that works--the system depends too
much on the fan.

I think all this is masked by the stock temperature gauge, which seems
to be too well-damped to show these interactions.

Rick "speaking of masking..." Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

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[Message index]

		[GMCnet] Fan Clutch By: USAussie on Wed, 21 October 2009 22:36
		Re: [GMCnet] Fan Clutch By: Ken Burton on Wed, 21 October 2009 22:43
		Re: [GMCnet] Fan Clutch By: Rick Denney on Thu, 22 October 2009 00:33
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Thu, 22 October 2009 00:49
		Re: [GMCnet] Fan Clutch By: USAussie on Thu, 22 October 2009 02:57
		Re: [GMCnet] Fan Clutch By: Oldngray on Thu, 22 October 2009 07:22
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Thu, 22 October 2009 10:54
		Re: [GMCnet] Fan Clutch By: USAussie on Thu, 22 October 2009 15:37
		Re: [GMCnet] Fan Clutch By: Ray Erspamer on Thu, 22 October 2009 10:32
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Fri, 23 October 2009 00:44
		Re: [GMCnet] Fan Clutch By: Ken Burton on Fri, 23 October 2009 01:43
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Fri, 23 October 2009 09:28
		Re: [GMCnet] Fan Clutch By: Rick Denney on Fri, 23 October 2009 14:50
		Re: [GMCnet] Fan Clutch By: USAussie on Fri, 23 October 2009 18:31
		Re: [GMCnet] Fan Clutch By: Rick Denney on Sat, 24 October 2009 01:35
		Re: [GMCnet] Fan Clutch By: USAussie on Sat, 24 October 2009 02:47
		Re: [GMCnet] Fan Clutch By: emerystora on Sat, 24 October 2009 09:37
		Re: [GMCnet] Fan Clutch By: Ken Burton on Fri, 23 October 2009 21:18
		Re: [GMCnet] Fan Clutch By: WD0AFQ on Fri, 23 October 2009 22:56
		Re: [GMCnet] Fan Clutch By: Rick Denney on Sat, 24 October 2009 02:44
		Re: [GMCnet] Fan Clutch By: Rick Denney on Sat, 24 October 2009 02:38
		Re: [GMCnet] Fan Clutch By: GMCWiperMan on Sat, 24 October 2009 07:00
		Re: [GMCnet] Fan Clutch By: Ken Burton on Sat, 24 October 2009 09:09
		Re: [GMCnet] Fan Clutch By: USAussie on Thu, 22 October 2009 02:55
		Re: [GMCnet] Fan Clutch By: Rick Denney on Thu, 22 October 2009 04:05
		Re: [GMCnet] Fan Clutch By: rgleas on Sun, 25 October 2009 11:30
		Re: [GMCnet] Fan Clutch By: emerystora on Sun, 25 October 2009 11:52
		Re: [GMCnet] Fan Clutch By: Gary Casey on Sun, 25 October 2009 12:32
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Sun, 25 October 2009 13:05
		Re: [GMCnet] Fan Clutch By: emerystora on Sun, 25 October 2009 13:29
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Sun, 25 October 2009 17:38
		Re: [GMCnet] Fan Clutch By: emerystora on Sun, 25 October 2009 18:02
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Sun, 25 October 2009 18:51
		Re: [GMCnet] Fan Clutch By: RF_Burns on Thu, 22 October 2009 07:54
		Re: [GMCnet] Fan Clutch By: Ray Erspamer on Thu, 22 October 2009 10:40
		Re: [GMCnet] Fan Clutch By: GMCWiperMan on Thu, 22 October 2009 15:09
		Re: [GMCnet] Fan Clutch By: Gary Casey on Thu, 22 October 2009 17:17
		Re: [GMCnet] Fan Clutch By: Ray Erspamer on Thu, 22 October 2009 17:21
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Thu, 22 October 2009 10:23
		Re: [GMCnet] Fan Clutch By: Rick Williams on Fri, 23 October 2009 09:05
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Fri, 23 October 2009 09:43
		Re: [GMCnet] Fan Clutch By: amansfield1104 on Fri, 23 October 2009 10:16
		Re: [GMCnet] Fan Clutch By: roy1 on Sat, 24 October 2009 21:16
		Re: [GMCnet] Fan Clutch By: Ken Burton on Sat, 24 October 2009 21:19
		Re: [GMCnet] Fan Clutch By: roy1 on Sat, 24 October 2009 21:38
		Re: [GMCnet] Fan Clutch By: Larry on Fri, 23 October 2009 12:36
		Re: [GMCnet] Fan Clutch By: Ray Erspamer on Fri, 23 October 2009 13:12
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Fri, 23 October 2009 13:16
		Re: [GMCnet] Fan Clutch By: Ray Erspamer on Fri, 23 October 2009 13:43
		Re: [GMCnet] Fan Clutch By: Ken Burton on Sat, 24 October 2009 09:45
		Re: [GMCnet] Fan Clutch By: Tin Gerbil on Sat, 24 October 2009 11:24
		[GMCnet] Horsepower and Torque Converter Efficiency By: Gary Casey on Sun, 25 October 2009 04:55
		Re: [GMCnet] Horsepower and Torque Converter Efficiency By: GMCWiperMan on Sun, 25 October 2009 06:29
		Re: [GMCnet] Horsepower and Torque Converter Efficiency By: Gary Casey on Sun, 25 October 2009 09:13
		[GMCnet] "six-speed" transmission By: Gary Casey on Sun, 25 October 2009 10:31
		Re: [GMCnet] "six-speed" transmission By: emerystora on Sun, 25 October 2009 10:54
		Re: [GMCnet] "six-speed" transmission By: Gary Casey on Sun, 25 October 2009 12:02
		Re: [GMCnet] "six-speed" transmission By: emerystora on Sun, 25 October 2009 13:39
		Re: [GMCnet] "six-speed" transmission By: Gary Casey on Mon, 26 October 2009 07:07
		Re: [GMCnet] "six-speed" transmission By: Gary Casey on Sun, 25 October 2009 12:04
		Re: [GMCnet] "six-speed" transmission By: comcast on Sun, 25 October 2009 12:21
		Re: [GMCnet] "six-speed" transmission By: emerystora on Sun, 25 October 2009 14:01
		Re: [GMCnet] Horsepower and Torque Converter Efficiency By: Tin Gerbil on Sun, 25 October 2009 10:59

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