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I've changed my fan blade from a 4 to a 6 to see how it performs this summer. It had a bent blade, enough that it didn't have proper clearance when turned. I straightened it out best I could and the blades are mounted on some pretty thick metal, not so easy. We've all seen some sort of fan turn when blades aren't perfectly balanced. My question is could this put any strain on the water pump or have any other consequences? My thoughts are the generator belt is keeping the pump shaft from moving anyway. Disregard the smoke, it was the first start up of the year and the wind was blowing the exhaust back in the garage. 

 

 

 

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9 hours ago, Summershandy said:

I've changed my fan blade from a 4 to a 6 to see how it performs this summer. It had a bent blade, enough that it didn't have proper clearance when turned. I straightened it out best I could and the blades are mounted on some pretty thick metal, not so easy. We've all seen some sort of fan turn when blades aren't perfectly balanced. My question is could this put any strain on the water pump or have any other consequences? My thoughts are the generator belt is keeping the pump shaft from moving anyway. Disregard the smoke, it was the first start up of the year and the wind was blowing the exhaust back in the garage. 

 

 

 

take the fan to a metal or machine shop and ask them to make the blades all true, it's not that the fan is out of balance - that would cause water pump bearing and seal problems. it might be that one blade you reposition that needs a little more help.

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Never run a bent fan. Get another. I doubt anyone is good enough to get it really right after it has been bent. If it runs out of balance, it will take out the water pump bearing. When it finally lets go, it will destroy the radiator and probably the hood.

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Even if your blade is balanced perfectly even a small amount of pitch difference will cause the blade to wobble and eventually fail. Pitch gauges are available through HVAC supply businesses and are not expensive.

As stated a good true fan blade would be your best option. 

 
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DAYTON
 
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In case you cant get that fan squared up.  I just INSTALLED A 6 BLADE FAN ALL30100 18", ALLSTAR FROM AMAZON. 

Allstar ALL30100 18" Diameter 5/8" Pilot Hole Steel Mechanical Type Radiator Fan with 6-Blade

Clears the Harmonic balancer, a flexlite aluminum did not would have needed a good size spacer.  I chose this one because it also looks to be era appropriate.  

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Re the bent blade, I have successfully used a digital protractor to set  / adjust the altered fan blade pitches that were a result of making contact with  an unwelcome long thick serpent like visitor in the fan  cowling during the winter monthes.  The readings are in half degree's so you alter  the pitch and the balance to almost perfect conditions given time and perseverance.

I also used these for adjustable blade pitch angles on gas compressors fin coolers in the offshore gas cooler fin fans and earth moving equipment with variable pitch cooler fans.  

These digital protractors  / angle meters also come in handy for setting drive line angles for driveshafts, universal joints etc .

The one I purchased has a magnetic base, so once you set the zero baseline, then attach it to the fan blade for the pitch angle,  they are an ideal  tool for checking  that angle with a high degree of accuracy.    

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  • 2 weeks later...
On 6/14/2020 at 3:51 PM, pontiac1953 said:

take the fan to a metal or machine shop and ask them to make the blades all true, it's not that the fan is out of balance - that would cause water pump bearing and seal problems. it might be that one blade you reposition that needs a little more help.

did the 6 blade fan get checked and worked to run true ?

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I played around with it on a smooth flat table. Laid it flat so I could see any space under each blade. I was able to get the blade in question in a much better position. It's still not perfect and not sure how perfect it has to be. Money is a little tight right now to take it to a shop. 

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5 hours ago, Summershandy said:

I played around with it on a smooth flat table. Laid it flat so I could see any space under each blade. I was able to get the blade in question in a much better position. It's still not perfect and not sure how perfect it has to be. Money is a little tight right now to take it to a shop. 

you probably have it close enough to use it without any concerns.

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OK....I see where we're going with this. I have a good judgement on things. Because I like things perfect doesn't mean they always will be. I tend to be an over thinker. The fan is of solid construction and I believe I got those blades near perfect. Just for fun I'll re-install it and take another video. Whether it stays on or not is another story. Thanks for all the suggestions!

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2 hours ago, JFranklin said:

Just don't stick your face under the hood while it is running!

it's not like a thin metal or fiberglass flex fan that we're talking about here, at the mounting circle there 2 layers of 1/8 inch steel spotwelded together - the 4 bolt holes goes through both of them, away from the bolt circle the solid piece of 1/8 inch steel continues out to the 6 blade mounting arms, each of the 6 arms have 4 big solid rivets fastening each blade to the arm, each blade is made from 1/16 inch steel, so summershandy has nothing to worry about a blade ever possibly coming unriveted and flying off the fan.

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Charles is right. It's thick and heavy. No worries about the fan flying apart. I'm going to keep working on the blade orientation. 

Most of the blades sit flat on the table about 43mm pitch. Middle picture is the blade in question. 

 

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