BOBTHEBOPPER
Member
- Joined
- Dec 13, 2020
- Threads
- 2
- Messages
- 10
Here is a real puzzle on an old Tecumseh HM80 with internal ignition coil. I have a Craftsman snow blower (late 70s vintage) which has always been kept outside and kept covered, and each year around November I uncover to ready it for the winter season. Usually my only problems are pulling the flywheel, removing the mouse nests, cleaning and resetting the points and changing the oil. I have been doing this for the last 18 years since getting the oldie but goodie. Here begins the mystery of the growing stator laminations, After cleaning and gapping the points (never checked the engine timing in about 6 years) replacing the flywheel and rotating the flywheel by hand I noticed it would hit something, rotated it backwards and noticed it was hitting something way short of 360 degrees, pulled the flywheel again and through careful examination noticed the magnet assembly on the flywheel was striking the stator laminations (both directions of rotation). Examined the flywheel magnets and they were screwed tight to the flywheel, no play. My next thought was maybe a bent magneto end on the crankshaft, checked by rotation and no deflection there. My next thought was to check the lamination assembly riveted to the stator base plate to see if it was lose or bent, everything was tight not bent or deformed. Then I checked the stator assembly to see if it could have slipped out of position in relation to the crankshaft but noticed the stator assembly fits on a boss on the engine magneto case (no adjustment there except for timing). All checked out OK. Now what to check? Magneto assembly in fixed position in relation to the crankshaft and magneto engine cover, all parts of stator assembly tight and not deformed, flywheel magnet assembly tight to flywheel and not distorted, crankshaft not bent and flywheel not distorted and fits tight to crankshaft. The only other issue could be a worn main crankshaft bushing on engine magneto case and that was checked (no slop in crankshaft at magneto end). In order to solve the laminations hitting the flywheel I had no choice but to file down the laminations to get clearance to the flywheel magnets. Being the stator assembly is internal to the flywheel this was a trial and error procedure to get a close fit to the flywheel magnets as possible (external stator clearance to the flywheel magnets is about .013 clearance) but no way to check internal magneto clearance. After much filing and measuring with putty I was able to obtain a fairly accurate fit. Assembled everything and ran engine. seems to run fine but my question is WHAT COULD HAVE CAUSED THIS PROBLEM, I AM STUMPED. Can someone explain this phenomenon? Metal does not grow (AT LEAST ON THIS PLANET). Would appreciate any comments. BOBTHEBOPPER 60 years of engine repairing.