Autopsy of a BX2750A Snowblower

[DustyRusty]

Let me start with saying that this isn't to lay blame to the previous owner, but as a lesson as to what happens when a few set screws are not tightened enough or parts are assembled incorrectly. Even the assembled incorrectly might be a result of a factory assembler not doing his job correctly. Below are the pictures of what I found, and not all of what I found is documented with pictures.
As some of you might remember I purchased a used snow blower that was advertised on these forums by another member. The one thing that I did immediately notice is that aside from the rust at the bottom of the snow blower housing, is that it was well maintained by the previous owner. Rust is something that all of us in New England have to endure, because they use way too much salt on the roads, and the newer type of snow melting products are even more corrosive than the salt that was used 20 years ago.
The previous owner told me that the snow blower ingested a chunk of ice, and that caused the fan to move forward into the bottom of the housing, and self destruct. Upon examination once I had the snow blower home, I did find that was true. I also found that the set screws on the sprocket had come loose, causing the fan shaft to move forward causing the damage. I also found that the shear pin on the fan had failed, as it should. I myself hit a rock that was buried in the snow, and it also bent my fan in a similar way as this fan was bent. This type of damage is beyond operator control, because you can't see through the snow to what might be below. When you hit such an object, the fan stops suddenly, and since the lower drive sprocket is still turning, the chain is the next item that will suffer a catastrophic failure. One good reason to always keep a spare chain in your spare parts collection.

 

[DustyRusty]

The next thing that I found, I believe is a assembly problem from the factory in Canada, where the snow blowers are manufactured. The assembly of the bearings and retainers were done incorrectly. The bearing is supposed to be held in place between the two bearing plates, which wasn't done on the one bearing closest to the drive shaft. One of the bearing plates was mounted on the outside of the steel frame, and the other was mounted on the inside of the steel frame. When I attempted to remove the bearing, I couldn't get the shaft out, because the bearing plate hole was too small to allow the gear that is welded to the shaft to pass through it. I was able to remove the bearing with the aid of a puller. On the other side of the shaft, the bearing plates were installed correctly, and they were on the inside of the steel frame, which also cause me difficulty. Checking with the parts breakdown, it appears that this is correct. With a little bit of MacGyvering, I was able to get it positioned to get my puller onto the bearing, and pull it off.
What I did learn from all of this, is that the Allan screws on these machines do sometimes loosen, and that periodic checking of them will save you a lot of aggravation in the middle of a snow storm.
After assessing this machine's parts, I decided that it was worth doing a complete rebuild on it. Once I get all the parts, I will do another post.

 

[sagor]

Dusty. I've had that fan blade get bent out with a few rocks as well (about 3 times). There seems to be a design flaw where the fan is not quite square with everything else, or clearances are not that good. This is on a brand new BX2750D. Then, the extra flange on the left side (near exit) on the front is too close in, causing the fan to catch rocks/etc, as it goes by. A big rock, and bang, the shear pin goes but not before deforming the fan blade so it sticks out and has to be bent back in.

I somewhat solved this issue by bending that extra flange plate on the left side (as viewed from the front) outwards with a simple pipe wrench. This makes it so that any rock in the round fan housing does not catch the flange edge on the way out. Unless it is a HUGE rock of course.
Since this modification, I have not had anything (ie rocks) cause any problems, and have not blown a shear pin after. However, come next winter, with fresh rocks, it may be a different story...

What I found was that the fan has about a 1/4" clearance at the front of the housing, but only about 1/8" at that extra flange on the left (viewed from front). A rock rotating in the housing is "ok", but if it was at the front edge, it caught the flange edge easily. Bang...

Check your blower for this. No harm bending out that flange a bit. It may affect the efficiency of the blower by 1% or 2%, but saved me a lot of grief...