How do you replace the impeller on an MTD 2 stage snow blower?

Answer 1

This is a rough, from-memory-write-up, based on a larger 10hp "Troy Built" brand, but was definitely an MTD, model 665 or similar

• Remove 3 bolts on each side of the "bucket" (term I'll use that houses the auger and impeller)
  This releases the auger from its mountings and it'll be hanging by the shaft going into the impeller
  
  NOTE: this step could be deferred to later - we did it to see if the auger/impeller could just be simpl pulled out without having to dig deeper.
  
  
• Remove the gas cap - put a piece of plastic over tank opening and put the gas cap back on. This will allow you to tilt the entire machine up and rest it on the face of the 'bucket'
  
  
• With the machine now sitting up, you can remove 6 bolts that hold a cover on - exposing the bottom of the belts & pullies
  
  
• Put the machine back on its feet
  
  
• Remove the belt cover - 2 bolts and lift the plastic cover off
  
  
• Disconnect the drive belt(s) from the engine pulley
  
  
• Remove the 6 nuts, 3 per side, at the backside of the bucket that hold it to the engine/power unit.
  
  
• There is a spring that goes from the auger drive cable to the lever that controls the drive belt idler pulley (pullies) - disconnect it.
  
  
• Separate the 2 parts: bucket from the engine/power unit. Set the power unit aside as we're done with it until it's time for reassembly
  
  
• On the backside of the bucket now, you can see and access the large drive belt pulley (or pullies)
  
  
• There is a bolt in the center of the pulley wheel - that's threaded into the backend of the driveshaft that goes through the impeller, into the gear housing that in-turn drives the augers.
  
  
• Remove that bolt -
  
  
• Slide the pullies off the driveshaft
  NOTE: take a picture or remember what the order & sequence looks like!!!!
  
  
• At this point, if all has gone well, and I haven't forgotten any steps, the impeller / augers assembly should slide out of the bucket
  
  NOTE: there is a bearing the shaft goes through that just 'sits' in the center hole on the backside of the bucket - it may just fall out. Take note of which side faces which direction
  
  
• Inspect the impeller for 2 spring/tension pins that secure it to the drive shaft.
  Remove them with a punch or other handy punch-like device
  
  
• A good size 3-arm gear puller really came in handy at this stage for removing the impeller from the shaft

Reassembly notes:

• Just to say this out-loud: reverse the above steps to reassemble
  
• grease the shaft to help get the impeller onto the driveshaft - lining it up with the tension pin holes is a little challenging
• Remember that picture you took of the large belt pullies and stuff on the backside of the bucket, you're gonna need it
• When getting to the point of hooking up the bucket back to the engine power unit:
• • Put the 2 nuts on the bottom studs to hold the pieces loosely, and so you can tilt the joint up into a V-shape
  • Reconnect the spring back onto the idle pulley arm - we had to disconnect the cable up at the handle to weasel the spring back onto that arm
  • Reconnect the belts at this point -
    Thought: all of this procedure might be covered in the Owners Manual regarding belt changes
  • Finish installing the rest of the connecting nuts to get the two halves back together
• Grease up the augers and those nylon inserts they ride on
• Tools: most everything was done with 3/8, 7/16, 1/2 & 9/16ths sockets & extensions, 7/16 wrench, and needle-nose pliers for the spring
  

My project was due to damage from picking up a newspaper hidden in the snow, the impeller was bent and the pulley adaptor was broken. The impeller was $36 and the pulley adaptor was $12

Sidebar: If I hadn't taken apart a 1974 Ariens snow thrower a few days before my neighbor stopped by last weekend with his big MTD/Troy Bilt, I wouldn't have had a clue how to help him fix his.

It appears this same basic design concept applies to a wide range of 2 stage snow throwers. Amazing how similar the whole process was.

Good luck and good snow throwing - now... Let it snow!!!