Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Looking at the photos automatic1stdown posted, from that point of view the impeller spins counter clockwise. As the tips of the auger blades come around they pushes snow into the impeller, which under the right conditions, throws some of it forward and to the right as the bottom of the impeller is moving to the right and very fast. I suspect that’s the cause of the leak.

In light snow the auger tips don’t shove enough snow into the impeller each time they comes around to cause the impeller to throw it out. In heavy snow, the snow that would be thrown out is blocked by snow in the auger. There is likely an range of snow where the leakage is maximum and in more or less snow the leakage is less.

In my opinion the leakage is a design tradeoff of the three blade impeller, which may increase the maximum capacity of the machine for a given engine power, but also results in some leakage when the snow is within a certain depth range and weight.  I’m guessing, but with the three blade design the impeller may spin faster as there's more time between blades for a given RPM than with a four blade impeller.  The higher RPM may be the root cause of the leakage, but also helps throw snow further.

Being the leakage is always to the right side (left from behind) you can minimize the problem by clearing in a pattern such that the leakage is to the side that has not been cleared yet. That might not be possible all the time, nor necessary under many conditions.