Another (possibly dumb) question
Thread Starter
Team Owner
Joined: Jul 2008
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
Another (possibly dumb) question
The fan attached to the fan clutch, which way is it supposed to be pushing air? Gut feel tells me that it should be pushing air toward the back of the car, like pulling air over the radiator. Is this correct? What would happen if my fan blade was on backwards, would it be trying to push air the wrong way?
Team Owner
Joined: Sep 2006
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From: Westminster Maryland
Hi PK,
From what I can see of the single blade in the picture... the fans on backwards.
Regards,
Alan
PS: Nice looking engine compartment!!!
From what I can see of the single blade in the picture... the fans on backwards.
Regards,
Alan
PS: Nice looking engine compartment!!!
Last edited by Alan 71; Oct 6, 2008 at 04:26 PM.
Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
Alan, you are mostly correct, the fan isn't and can't just be backwards. Even if he removes it, flips it, and re-installs it he'll get the same result.
Quite simply he has a reverse flow fan on a standard rotation pump.
The OP just needs a standard rotation fan and clutch to bolt to the water pump.
Last edited by Durango_Boy; Oct 6, 2008 at 05:50 PM.
Team Owner
Joined: Sep 2006
Posts: 31,160
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From: Westminster Maryland
Hi DB,
I just looked again. On my 71 the fan blades can be bolted to the fan clutch frontwards or backwards, HONEST. It changes the direction the curve in the blade is facing, and thus the direction the air moves.
Regards,
Alan
I just looked again. On my 71 the fan blades can be bolted to the fan clutch frontwards or backwards, HONEST. It changes the direction the curve in the blade is facing, and thus the direction the air moves.
Regards,
Alan
Last edited by Alan 71; Oct 6, 2008 at 05:42 PM.
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Team Owner
Joined: Aug 2006
Posts: 24,125
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From: Columbia Missouri
Okay I did some checking and actually his fan is correct. Looking forward at the fan from the front, the engine would rotate clockwise. This means that his fan would be spinning counter clockwise from the back view...which is how we are seeing it. This means his is the correct fan.
What I meant was, about flipping that fan, was that while it will FIT backwards...the blade direction won't change and it would still be moving the air the wrong way, even after it was flipped.
That being said, his fan is right, so if the engine is running correctly it should be pulling air through the radiator towards the engine.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
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From: McHenry Illinois
If the fan were on backwards, it would be very inefficient and barely move any air at all. The picture is very decieving, the blade in the top of the pic looks like the convex side is facing us, but the blade at the left and lower shows the concave side facing us, which is correct. (statement, not a question)
Last edited by '75; Oct 6, 2008 at 08:46 PM. Reason: unclear response
Drifting
Joined: Apr 2007
Posts: 1,970
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From: Cameron Park CA
The blade facing straight up looks wrong, but the blade behind the radiator hose looks correct. The concave side should be towards the engine; it's a more efficient airfoil that way. Reversing the fan will NOT change the way the air flows. It will just make the fan more efficient than the way it is now. Gordonm's fan is correct!
Picture it this way: If you look down on the fan blade at the top of the circle, as if you were standing on the air cleaner, the side of the blade on your left will always be closer to the radiator, no matter which way it's mounted. Make a drawing of a fan blade as if looking at it from the top, no matter which way you turn the paper, it will still have the left side closer to the radiator.
In any case, the fan will pull air through the radiator no matter which way it's mounted, but one way works better than the other. The General didn't put those nice curved blades on there because they look nice, they did it to pull more air than a flat blade.
Cheers,
Pete
Picture it this way: If you look down on the fan blade at the top of the circle, as if you were standing on the air cleaner, the side of the blade on your left will always be closer to the radiator, no matter which way it's mounted. Make a drawing of a fan blade as if looking at it from the top, no matter which way you turn the paper, it will still have the left side closer to the radiator.
In any case, the fan will pull air through the radiator no matter which way it's mounted, but one way works better than the other. The General didn't put those nice curved blades on there because they look nice, they did it to pull more air than a flat blade.
Cheers,
Pete
Last edited by PeteZO6; Oct 6, 2008 at 08:08 PM.
Sucks getting older. Can't see anymore!
Race Director
Joined: May 2006
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From: Dayton, Ohio
In any case, the fan will pull air through the radiator no matter which way it's mounted, but one way works better than the other. The General didn't put those nice curved blades on there because they look nice, they did it to pull more air than a flat blade.
Cheers,
Pete
Reversing the blade only reduces its efficiency....doesnt reverse air flow direction.
Thread Starter
Team Owner
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
Thanks guys! I think I was just having a brain cramp yesterday at work, sorry the picture was weak, it was the only one I had of my engine on my work computer. I went home and opened the hood and had a good look around. The fan blades face the proper direction and the fan itself cannot be on the wrong way, it would not fit if I turned it around because the curve of the fan blade comes outside the fan housing. Turning it around would mean that I would be trying to fit the bigger part that goes on the outside of the housing into the housing, which would not work. That doesn't mean I particularly like that fan, nor am I particularly thrilled with my fan clutch. With the engine cold, it is VERY hard to turn the clutch by hand. IMO, this clutch is too tight and is taking too much Hp from my engine to keep it turning at high speed all the time. It is also annoyingly noisy at engine speeds above about 2700. I am thinking of changing the fan clutch, and also possibly the fan. Any suggestions are appreciated.
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
The fact that it is hard to turn means it is working good...assuming it doesn't turn easy even when hot. To test it, drive until the engine is hot. Stop, pop the hood, and kill the engine while watching the fan. If it makes more than a few complete revolutions after the engine stops then the clutch is bad. If it stops quick it's good.
The noise sucks, but that keeps your engine cooler.
The only way to avoid the noise would be to switch to an electric fan or fan set which is a constant whine instead of an RPM controlled WHOOSH.
The noise sucks, but that keeps your engine cooler.
The only way to avoid the noise would be to switch to an electric fan or fan set which is a constant whine instead of an RPM controlled WHOOSH.
Thread Starter
Team Owner
Joined: Jul 2008
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
I thought the fan was supposed to turn easily when cold, and stiffen up when hot? I was under the impression that one that is real stiff when cold is no good since I am effectively not getting any "clutching" action at all. Am I off base here?
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
Could be a perception difference seeing as how there is no factual definition of 'easy.'
Perform the HOT test to find out if it's bad or not.
Le Mans Master
Joined: Jan 2007
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From: Peekskill NY
When my engine is cold it feels firm, but not real hard to turn. Stops quickly when I shut her down, and I don't hear much woosh noise from the fan. Now I'm curious if there's much difference when the engine is hot. I'll have to check that out.