Another (possibly dumb) question
Le Mans Master
Joined: Jan 2006
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From: Butler Pa
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
After viewing your pic of your fan I see its an optical illusion as to the direction of the fan blades.The fan is on correctly judging by the points at the outer edges of the fan and the notches on the rearward side.
Drifting
Joined: Aug 2005
Posts: 1,430
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From: Hamilton NJ
If the fan clutch is new and a really good one it will be hard to turn if completely cold but in around 30 seconds of running it will loosen up.Inside the fan clutch is silicone fluid and it will be thick until it spins for a few seconds.If after running the engine for 30 seconds to a minute it still is hard to turn then your right you need to replace it.
Le Mans Master
Joined: Jan 2006
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From: Butler Pa
What would cause this? I'm not too knowledgeable on fan clutches and need to learn. My understanding is that when they go bad an need replacement it is largely due to loss of silicone and inability of the clutch to engage at higher temps. You get lower RPM and less efficient cooling when needed. I didn't know they could go bad by actually seizing up and always spinning at full blast?
Drifting
Joined: Aug 2005
Posts: 1,430
Likes: 8
From: Hamilton NJ
Well then...
Next obvious question...Is this a dangerous thing? Apart from the obvious reasons why you wouldn't want to use a seized fan clutch (drain on horespower at cooler operating temps and increased noise due to constant full speed spin) is there a safety risk? I've heard horror stories of Flex-Fans gone wild, but are there issues with housing failures on a seized fan clutch that may send the blade flying?
Next obvious question...Is this a dangerous thing? Apart from the obvious reasons why you wouldn't want to use a seized fan clutch (drain on horespower at cooler operating temps and increased noise due to constant full speed spin) is there a safety risk? I've heard horror stories of Flex-Fans gone wild, but are there issues with housing failures on a seized fan clutch that may send the blade flying?
Le Mans Master
Joined: Jan 2006
Posts: 6,504
Likes: 138
From: Butler Pa
Well then...
Next obvious question...Is this a dangerous thing? Apart from the obvious reasons why you wouldn't want to use a seized fan clutch (drain on horespower at cooler operating temps and increased noise due to constant full speed spin) is there a safety risk? I've heard horror stories of Flex-Fans gone wild, but are there issues with housing failures on a seized fan clutch that may send the blade flying?
Next obvious question...Is this a dangerous thing? Apart from the obvious reasons why you wouldn't want to use a seized fan clutch (drain on horespower at cooler operating temps and increased noise due to constant full speed spin) is there a safety risk? I've heard horror stories of Flex-Fans gone wild, but are there issues with housing failures on a seized fan clutch that may send the blade flying?
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
Melting Slicks
Joined: Aug 2005
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From: Lincoln CA
I don't mean to be contrary, but logic would decree that a clutch fan should be free spinning when the fluid is cold and hard to spin when the fluid is hot. Otherwise, the fan wouldn't turn at high temperatures and it would at low temperatures, which is just the opposite of what you want to happen. As far as bearings seizing, if they did then you would have the equivalent of an non-clutching fan. Why would that cause the fan to scatter? Just wondering.
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Team Owner
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
I don't mean to be contrary, but logic would decree that a clutch fan should be free spinning when the fluid is cold and hard to spin when the fluid is hot. Otherwise, the fan wouldn't turn at high temperatures and it would at low temperatures, which is just the opposite of what you want to happen. As far as bearings seizing, if they did then you would have the equivalent of an non-clutching fan. Why would that cause the fan to scatter? Just wondering.
Two possible reasons:
1. The centripetal forces generated from rotating the fan at, say, 5000 rpm are greater than the fan was designed to tolerate. Even if the new fan was designed to take redline, an old or corroded one could have lost some strength and come apart on you.
2. There could be a resonance frequency for the fan at some speed less than the redline. I would hope that the engineer who designed the fan checked on this, but then, we did have "Galloping Gertie", so you can never be sure.
Race Director
Joined: May 2006
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From: Dayton, Ohio
I don't mean to be contrary, but logic would decree that a clutch fan should be free spinning when the fluid is cold and hard to spin when the fluid is hot. Otherwise, the fan wouldn't turn at high temperatures and it would at low temperatures, which is just the opposite of what you want to happen. As far as bearings seizing, if they did then you would have the equivalent of an non-clutching fan. Why would that cause the fan to scatter? Just wondering.
Scattering fan? Fans that are to be clutch driven have bigger blades and more pitch and arent meant to reach redline.Fans that are fixed usually have smaller blades and have less pitch or less blades because they are going to follow engine rpm.
Team Owner
Joined: Jul 2006
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From: Kannapolis NC
PK, your fan is not correct. The two blades you can see don't even match. The engine turns counterclockwise (left looking from the driver's seat.) That blade that is to the right is curved the wrong way to pull air through the radiator. The one behind the hose looks like someone has straightened the curve. They should all be curved the same and the curve should pull air through the radiator when rotating counterclockwise. The clutch should be hard to turn. It should turn at engine speed when running steady, but slip when revving to avoid sucking power. Also at highway speed if more air is being forced through the radiator than the fan would pull, it allows the clutch to slip and not attempt to bog the engine by putting back pressure on the fan. Take a look at another Vette with the correct angles on the blades, it will be obvious to you the difference.
Here's a picture of the correct angle of the curves. Gordonm's is also correct.
Here's a picture of the correct angle of the curves. Gordonm's is also correct.
Last edited by 65GGvert; Oct 7, 2008 at 08:52 PM.
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
I respectfully disagree.
His fan IS correct, mounted correct, and would turn in a way to pull air through the radiator. It's yet to be determined if the clutch is good or bad.I know it's hard to tell in that picture. I altered it in Photoshop to get a better view of it without the shadows.
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Team Owner
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
Nice photoshop Wuttin!
I am convinced the fan is correct and on correctly. The fan is difficult to turn when cold, not like I have to lean on it to get it to turn, but I have to push on it with a lot more force than I remember on my old car. Of course, my old one was a small block so the fan was much smaller and probably needed a lot less force to drive it, so maybe my comparison is bad. I ran for about a minute and shut it off, the fan didn't seem to be perceptibly easier to turn. I took it out for a half hour cruise and opened the hood before shutting it down, the fan seemed to stop right with the engine and was still hard to turn.
I just don't think I am getting much clutching action out of it. I don't think it is harmful at all given the kind of driving I am doing right now where I am rarely over 50 mph. But at some point, I would like to take it for longer runs on highways and I would like to have some confidence that the fan and clutch are working correctly. I am not sure what I think of it at the moment.
I am convinced the fan is correct and on correctly. The fan is difficult to turn when cold, not like I have to lean on it to get it to turn, but I have to push on it with a lot more force than I remember on my old car. Of course, my old one was a small block so the fan was much smaller and probably needed a lot less force to drive it, so maybe my comparison is bad. I ran for about a minute and shut it off, the fan didn't seem to be perceptibly easier to turn. I took it out for a half hour cruise and opened the hood before shutting it down, the fan seemed to stop right with the engine and was still hard to turn.
I just don't think I am getting much clutching action out of it. I don't think it is harmful at all given the kind of driving I am doing right now where I am rarely over 50 mph. But at some point, I would like to take it for longer runs on highways and I would like to have some confidence that the fan and clutch are working correctly. I am not sure what I think of it at the moment.
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
I just don't think I am getting much clutching action out of it. I don't think it is harmful at all given the kind of driving I am doing right now where I am rarely over 50 mph. But at some point, I would like to take it for longer runs on highways and I would like to have some confidence that the fan and clutch are working correctly. I am not sure what I think of it at the moment.
Based on your description the fan is working as it should.
Drifting
Joined: Aug 2007
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is the clutch forward of the fan? and whats with that belt hanging out in deep space.
whats with the notches on the blades?
Thread Starter
Team Owner
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From: In limbo
St. Jude Donor '13-'15, '17 thru '22
The belt "hanging out into deep space" is the air conditioner compressor belt. I am not sure what you mean by "is the clutch forward of the fan", I believe the fan is bolted to the engine side of the clutch. I don't think I have ever seen it any other way. The fan is an oversized fan and does not fully fit inside the fan shroud, hence, the notches.
Drifting
Joined: Aug 2007
Posts: 1,924
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The belt "hanging out into deep space" is the air conditioner compressor belt. I am not sure what you mean by "is the clutch forward of the fan", I believe the fan is bolted to the engine side of the clutch. I don't think I have ever seen it any other way. The fan is an oversized fan and does not fully fit inside the fan shroud, hence, the notches.
I had a 90's Blazer once that had a reverse turning clutch fan. When the engine ran, the clutch revesed the spin of the fan so it was 'correct'.
But, When it seized up, it was pushing air toward the front of the car. It was very noisy.
your ac belt .. well.. all the ones I've ever seen hit 3 pulleys. The crank pulley, water pump pulley and the compressor. It just looks like yours is hitting the water pump and compressor. Doesnt seem like something GM would do, but, I only know what I know and I don't know what I don't know.
I would recommend getting the correct fan/clutch and correct shroud for the fan though. your fan scares me.
Race Director
Joined: May 2006
Posts: 16,528
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From: Dayton, Ohio
We need some big block owners on here. Thats a common big block fan and its on correctly.The only problem is the clutch is going bad and trying to lock up going by PKs description.
The fan I remember because when I see one it scares me.Imagine putting your hand on the fan shroud as the engine is running.
The fan I remember because when I see one it scares me.Imagine putting your hand on the fan shroud as the engine is running.