snow blower auger noise

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  #1  
Old 01-15-04, 06:56 PM
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Phantom auger noise in my snow blower

I have an 8HP pre MTD Troy- Bilt snow blower I bought in a crate in 1997 and never used till this year. I used the assembly manual and all adjustments and lubrication were performed with attention to every detail prior to putting the machine in service this winter. There is a mechanical gnashing sound when I engage the auger that is causing me some concern. I am afraid I am causing some kind of damage although there are no symptoms except the noise. The machine has two hours on it and the noise gets no better or worse.

I rechecked everything today including the 90wt. in the gearbox and all the belt adjustments. Re lubed everything and even disabled the plug and turned the impeller which moved the auger in an attempt to see if anything was binding. No binds at all and the keyways and roll pins are all tight.

If I engage the auger very slowly in an exagerated way- no noise. If I release the auger and re-engage it before the auger stops rotating-no noise. If I engage the auger in a normal fashion -gnashing noise.
Maybe this is normal for a gearbox driven auger? The machine handled the snow as well as my last one but I have no point of reference because the old one used a belt drive without a gearbox to run the second stage.

As always any help would be greatly appreciated,

Marc

PS -Snowman53,this is why I was interested in bearing lubrication.By the way the bearings check out fine.
 

Last edited by mml4; 01-16-04 at 05:25 AM.
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  #2  
Old 01-15-04, 08:01 PM
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Does it vibrate when the noise occurs? When the auger is running without the noise, does it begin making the noise when you bog it into some snow?
 
  #3  
Old 01-16-04, 05:21 AM
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It only makes the noise at the moment of engaging the auger. There is no vibration or shudder or any other significant event associated with this gnashing sound. As far as operating under load (snow) it works flawlessly.
I took the belt cover off and treated the belts with Permatex Belt Dressing. I removed the belt tensioner pulley and inspected it-no apparent problem. The thing that is so frustrating is I cant identify or locate exactly where the noise is comming from because of the exhaust noise.

Marc
 
  #4  
Old 01-16-04, 06:55 AM
jlm
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What kind of system engages the auger? By that I mean is there a cable with a spring that pulls the idler pulley in or is it a straight rod that goes to the lever ?
Just curious because this is an interesting problem.
Have you made sure the OD of the idler pulley isn't rubbing on something when engaging? Are the belts tracking straight when running?
Without actually hearing the noise it's difficult to say where it's coming from, my guess is a ball bearing is spinning loose either on the OD or ID fit to the auger shaft. As soon as a load hits it it stops spining and rotates like a ball bearing should. Just a guess!
Cheese will figure it out!
 
  #5  
Old 01-16-04, 09:11 AM
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Jlm- Belts are running true,no binds in anything, nothing is hitting anything. The linkage to the auger handle bar lever is a solid metal rod with a threaded adjuster attached to a spring. The directions for adjustment are to measure the spring in the tesnsion and relaxed position and subtract the two lengths and compare to the listed specification. The adjustment is right on spec.
The belt goes around a small pulley on the engine pto and around a large diameter drive pulley that is locked to a shaft using a woodruff key. The impeller fan is mounted on this same shaft using a roll pin and then the shaft enters the gearbox which controls the auger. The key and roll pin are tight with no play and if I turn this drive assembly by hand there are no binds .
The assembly is engaged by a belt tensioning pulley that engages the flat side of the belt. It is runningtrue and the bearing in it's center is neither bound nor does it appear to have any play.
This morning I removed the spark plug wire,locked down the auger control and pulled it through using the pull starter. The mechanism turned and each time I tried it screeched. Not the mechanical gnashing noise. I then started the engine and the screech left but the mechanical gnashing noise is back.
Thus is driving me nuts!!

Marc
 
  #6  
Old 01-16-04, 10:42 PM
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Just a thought...check to be sure none of the pulleys have a narrow spot in the V-groove. If the pulley is slightly narrower in a spot, it will cause the belt to jump up and down in it. It would probably do it all the time though, but it's hard to guess at this without hearing the noise. I'm not familiar with snowblowers anyway.

Also, try moving each spindle/shaft up and down, back and forth, and side to side. If there is any noise or excessive play, that could be the problem.

Can you tell if the noise is closer to the engine, or down near the auger? Here is a tip for locating noises...use a small hose, like a piece of fuel line. Put one end in your ear and move the other end around different parts of the machine until you hear the noise well. It will drastically reduce other noises, and let you focus on the noises that are directly in front of the end of the hose.
 
  #7  
Old 01-17-04, 12:50 PM
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I followed up the idea of vibration today and found nothing with excess play or rubbing against anything. The only thing I noticed is that the off side of the belt(the side opposite the tensioner pulley) shakes like hell on start up and then smooths out . I played with the belt adjustment in both directions but it had no effect on the gnashing sound. The belt does stop shaking once the auger is up to speed . The belt is not hitting anything.

The belt tensioner pulley rides on a spring controlled arm that allows it to be deflected against it's spring about 1/2 inch. It to shakes on start up initially but smooths out when the auger comes up to speed. The gnashing sound only lasts about 1/2 a second and then goes away.
Is it possible a shaking rubber belt is vibrating at such a high frequency that it could make a mechanical sound if it were "slapping" against it's pulley?
I fear I am dreaming up explanations out of exasperation!

Marc
 
  #8  
Old 01-17-04, 09:50 PM
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Does the noise quit at the same time the belt stops shaking?
 
  #9  
Old 01-18-04, 05:05 AM
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The noise is at the instant of start of rotation. The belt shakes for one or two second and smooths out when the auger is up to speed. The noise does not last as long as the belt shake.

Thanks for your concern,

Marc
 

Last edited by mml4; 01-18-04 at 01:02 PM.
  #10  
Old 01-18-04, 11:05 PM
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I don't think it's belt slap, but anything is possible. If you can't see anything wrong, it may be internal. I wish I could hear it, but at this point, that's all I can think of.
 
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