Sunday, January 23, 2011

Snowblower Fix

It's been quite a while since my last post. Not that I've been doing nothing, but mostly that I haven't had the drive to document anything online. Well, I've got the bug again, so here goes...

What follows is a quick documentation of my repairs to our Yard Machines / MTD snowblower model number 31AE160-129. There were a few inconsistancies with other online fix-it references so hopefully this is helpful for someone.

Our used Yard Machines snowblower started having some issues during the first major snowdump back in mid-December. It turns out the weld which connected the bar holding the rubber auger to the main drive shaft failed on one side. You can order a new auger assembly but it's quite expensive- close to $150 shipped. In the photo you can see how that after the weld failed, the rotating shaft actually ground out a larger hole in the steel bar.

Broken Weld, Still in Snowblower

I decided to find a local repair shop to re-weld the part. After trying to find a welder using google maps, I realized the gas station down the street would have welding equipment. I called them, and sure enough Herb's Service Center was game.

The only problem was I'd have to remove the assembly to bring it in. Only a few screws need to be removed to pull the cover off to expose the drive belt. Next up is the removal of the drive pulley. This proved to be an interesting problem. First, I wedged a piece of scrap wood in the auger. This prevented it from rotating when I removed the pulley. I broke out the breaker bar and socket to unscrew the pulley. From the online illustrations and descriptions I could find it appeared as though the pulley simply screwed onto the threaded auger shaft. The "expert" mechanics on varous forums also said the pulley was threaded using standard thread direction- e.g. counter clock wise to remove. I torqued on that thing as hard as I could and nothing budged, except for some warning bending and creaking noises coming from the snowblower frame.

Key Learning Moment:
After a few minutes of leaning on the breaker bar, I decided to sit back and think about it. After looking at how the auger works, it's obvious that a reasonable engineer would spec the pulley with reverse threads, so it self-tightens when encountering a load rather than self-loosens. I put the breaker back back on, tried turning to clockwise and seconds later the pulley popped loose.

Sweet 2x4 "fixture"

Broken Weld after Removal

The guys at Herbs did a decent job with the weld. Not too great looking cosmetically, but there is now plenty of metal to transmit torque to the rubber auger. They also spray painted it a nice shade of blue.

The snowblower went together easily, but seconds after putting it back to service the V-belt failed. Another lesson. Never use the cheap rubber V-belts they sell at every hardware store. Make sure and get the heavy-duty fiber reinforced belts specifically for snowblowers. The proper belt is a 1/2" x 35" large, MTD p/n 754-0101a. The replacement I found wasn't an MTB brand, but a Mitshubishi. It seems to work fine so far.


  1. Thanks so much for posting but sure wish I would have read this before I embarrassed myself in front of God and any nearby neighbors while turning the pulley bolt the wrong way ... like yourself I sat back and did the rotation imagination & came to the same conclusion REVERSE THREAD. The last time I seen that was on an old Chrysler when I broke the stud off; that funny stud with ((( L ))) stamped on the end
    Good grief it s***s to be me.

  2. I'm still puzzeled by why everything else I could find online said that bolt was standard threaded, not reverse threaded.