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

I have an older (12+ years I think) single stage simplicity snowthrower (551M - 1692320).  I had a buddy service it a few years back but I rarely used it and it would not start this year.  I bought the carb kit etc and it now starts and runs strong but under a wet load the auger stops...the engine is running fine though.  I figured it was perhaps a belt adjustment.  The manual says to measure the spring (I assume the one at then of the cable) and then pull back the bar and measure again.  It should expand 7/16".  If not adjust the cable.  Well, I have my cable adjusted as far down as I can without the lower nut coming off....its not quite 7/16" though.  It did throw better for 10 minutes, then I heard a squeal, then it stopped going thru heavier snow again.  So now I figured its probably the belt or perhaps the pther spring towards the front.  I went to the dealer and they had ONE belt left but saved for someone else! They did hold them together and they both looked the same length but perhaps mine had become more elastic with age...?   While the belt was off I saw it said MTD and some number I can not make out.  Why would an MTD belt be on a SImplicity thrower?  I thought maybe my buddy changed it a couple years back with perhaps a non oem belt but he does not remember doing so...it should be the OEM belt.  Anyway, what do you guys think...a bad belt, a bad spring...or its just 12+ years old and there is some sort of engine issue...?