Snowblower, grove in idler pulley

[wormwood1978]

5 year old Craftsman 22inch Snowblower.

Why is the auger belt causing a groove to develop in the idler pulley?

Background:
Earlier this year, the wormgear in auger gearbox stripped out. Because I could not just get the wormgear, I had to replace the entire gearbox. Shortly after, the auger again would not turn and I noticed the auger belt was fraying and the idler pulley was almost destroyed. I changed out the belt and the idler pulley. I tightening the belt up just a little by adding a little more tension to the auger engagement cable because it was slipping. I do not think the belt is too tight because I can only loosen it up slightly before its looseness is maxed out.

I've thought through various possibilites including did I mess up the gearbox installation, is the idler pulley not properly lined up, is the belt too tight. I just don't know. The new pulley which now has a good grove in it (whereas it was smooth when new) only has 3 or 4 hours on it.

 

[heyu]

Possibly the pulley has some tight spots in the bearing and / or stops spinning -----causing the belt to rub a groove into it

 

[Nayov]

Originally Posted By: wormwood1978

Earlier this year, the wormgear in auger gearbox stripped out.


Plastic or metal gears? I have an '06 Craftsman with no problems with the auger. I wonder if late model snowblowers are now equipped with plastic gears. If so, that's a new low.

My '09 Toro lawnmower's worm gear stripped after 4 years, a plastic gear.

 

[wormwood1978]

The worm gear was a large heavy brass gear. It lasted four years. It was completely shredded. No idea why. I never jammed it. Maybe just four years of wear or the occasional wetter heavier snow.

 

[andyd]

Any lube? I checked mine last yr and it was dry. I bought a bottle of 80-90 MTL and filled the gear box up. It doesn't leak.It is formulated for use with brass or bronze parts. Diff oils will sometimes eat brass if it has sulfur in it. Its a little thin but gears work great.

 

[wormwood1978]

Originally Posted By: andyd
Any lube? I checked mine last yr and it was dry. I bought a bottle of 80-90 MTL and filled the gear box up. It doesn't leak.It is formulated for use with brass or bronze parts. Diff oils will sometimes eat brass if it has sulfur in it. Its a little thin but gears work great.


Yes the gearbox was heavily greased. Don't know why it stripped

 

[JTK]

Could have been a manufacturing anomaly with the worm-gear itself, provided it was well lubed. The auger shear pins should have sheared before any damage to the worm gear assembly happened from shock loads. Over-loading shouldn't happen because the auger belt should slip, or the engine stall. You should remove, lube and replace the shear pins yearly and you're supposed to lube the space between the auger tube and and auger axle as well.

In regards to the worn tensioner, I'd say too much spring/cable tension or just a really cheap idler.

 

[wormwood1978]

Originally Posted By: JTK
Could have been a manufacturing anomaly with the worm-gear itself, provided it was well lubed. The auger shear pins should have sheared before any damage to the worm gear assembly happened from shock loads. Over-loading shouldn't happen because the auger belt should slip, or the engine stall. You should remove, lube and replace the shear pins yearly and you're supposed to lube the space between the auger tube and and auger axle as well.

In regards to the worn tensioner, I'd say too much spring/cable tension or just a really cheap idler.


After some input on another forum, I think there might be an alignment issue with the idler pulley. I will look at it closer this weekend and may add a spacer or a couple of washers. While it is possible the idler pulley was of poor quality, the original burned out and now the replacement is quickly going, so I think something is causing it. I really don't believe it is a cable tension issue, I only have it tightened up slightly from maximum looseness. I do appreciate the input though.

 

[JTK]

Glancing again at your pic, it looks like the end of the tensioner, closest to the engine is worn down to a smaller diameter than the rest of the pulley? Is it coming into contact with the drive pulley on the engine?

 

[wormwood1978]

Originally Posted By: JTK
Glancing again at your pic, it looks like the end of the tensioner, closest to the engine is worn down to a smaller diameter than the rest of the pulley? Is it coming into contact with the drive pulley on the engine?


No, I don't think the end of the idler/tension pulley is any narrower than the rest of the pulley. The narrow spot on the pulley is where the belt appears to be digging into it. Here is the picture of the last idler pulley I replaced next to the pulley I replaced it with. The new looking pulley is the same pulley beginning to show wear in the first picture I posted.

 

[JTK]

Wear like that to me indicates this tensioner is rubbing against something metallic, when it's in the engaged position.

 

[wormwood1978]

Originally Posted By: JTK
Wear like that to me indicates this tensioner is rubbing against something metallic, when it's in the engaged position.


I'm gonna work on the machine on Sunday and see what I come up with. Thanks for given me another thing to look for.

 

[wormwood1978]

Originally Posted By: JTK
Wear like that to me indicates this tensioner is rubbing against something metallic, when it's in the engaged position.


Turns out the idler pulley is pressing up against the auger pulley when it is in the engaged position. That is what is causes a band to wear on the idler pulley. I backed off the idler pulley to max looseness and I don't think there is contact now. The tension I did have set was only a little and to stop the auger belt from slipping off the pulley.