This spring I charged the 2019 battery and it started the engine (which had sat all winter) with about 3-4 cranks. I started driving the mower to the lawn when I discovered the manual blade clutch was not engaging. So I headed back to the driveway work area to fix the blade clutch. Once the blade clutch was loosened, lubed and fixed, I tried starting the mower again. Click. Click. Uh-oh, the 4 year old battery probably charged enough to start the engine once and then failed on 2nd try. I grabbed jumper cables and hooked up a car battery and all I got was Click. Click. So it wasn't the battery. The starter motor was "stuck".
I took the starter motor off the engine and marked the alignment of the front housing, stator housing and rear brush housing with a scribe lines. I took the black rubber cap off the end of the shaft (internal ridge on the cap fits a groove in the shaft). This model is the 3rd generation with the welded nut on the end of the shaft.
The motor shaft wouldn't rotate and the pinion was stuck on the shaft. I had nothing to lose attempting to fix (I've fixed dozens of auto/tractor/mower starters over the decades).
I removed long machine screws holding the starter together and pulled the housings apart. The helical gear on the shaft was bone dry as was the rear rotor bushing in the brush end cap. I used a watchmakers push oiler to put 3 drops of Kano Kroil on the helical shaft and used a screwdriver to work the 'pinion' free. As the Kroil got distributed along the shaft the pinion would move and slide as expected. I dried off the Kroil and put on 3 drops of lubricating oil on the shaft and worked the pinion back and forth along helix.
Then disaster struck when I moved the brush end cap too far and the brushes slipped off the commutator. Since it was off all the way, I put 7-8 drops of lube in the rear brush holder end cap bushing and a couple drops on the brush end of the motor shaft itself.
To get the brushes back on the commutator, I needed something to hold the brushes against the springs while getting the brush holder back in place. I took some 0.060" welding rod (thickness isn't critical but it had to be stiff enough to act as a lever against the force of the brush spring) and cut four 1 1/2" long 'rods'. I stuck each rod into one of the brush holders on the end cap, with the brush slightly preloaded against its spring. Each rod would serve as a lever to hold the brushes in place, against spring pressure, in order to get everything back around the commutator. You can see the three of the rods, one at 12:00, one at 3:00 and one at 6:00 sticking out of the brush end cap in the photo below.
With a thumb on one rod and a finger on each remaining rod, I could squeeze all four rods and their brushes towards the center and managed to pop the brush holder cap with its spring loaded brushes back onto the commutator. Once the brushes were back on the commutator, I pulled the rods out.
I screwed the starter pieces back together and mounted it back on the engine. The battery spun the starter just fine and the engine started. The starter motor has worked flawlessly and started the engine well over a dozen times over the past three weeks, so it looks like a good fix.
Six years of northern Illinois spring and fall days when moisture condenses on any metal part at ambient temperature (cold storage in the garage) just locked all the moing the pieces up in the absence of lubrication.
If you run into the same situation, be every sparing when applying lubrication and make sure that any oil goes only on the helix shaft. Use as little as possible. The pinion is driven by two cone shaped friction pieces and any oil that gets on the cones will allow the cones to slip, so the starter will run but the pinion won't drive the flywheel if the friction cones slip because of oil on the cones.
I took the starter motor off the engine and marked the alignment of the front housing, stator housing and rear brush housing with a scribe lines. I took the black rubber cap off the end of the shaft (internal ridge on the cap fits a groove in the shaft). This model is the 3rd generation with the welded nut on the end of the shaft.
The motor shaft wouldn't rotate and the pinion was stuck on the shaft. I had nothing to lose attempting to fix (I've fixed dozens of auto/tractor/mower starters over the decades).
I removed long machine screws holding the starter together and pulled the housings apart. The helical gear on the shaft was bone dry as was the rear rotor bushing in the brush end cap. I used a watchmakers push oiler to put 3 drops of Kano Kroil on the helical shaft and used a screwdriver to work the 'pinion' free. As the Kroil got distributed along the shaft the pinion would move and slide as expected. I dried off the Kroil and put on 3 drops of lubricating oil on the shaft and worked the pinion back and forth along helix.
Then disaster struck when I moved the brush end cap too far and the brushes slipped off the commutator. Since it was off all the way, I put 7-8 drops of lube in the rear brush holder end cap bushing and a couple drops on the brush end of the motor shaft itself.
To get the brushes back on the commutator, I needed something to hold the brushes against the springs while getting the brush holder back in place. I took some 0.060" welding rod (thickness isn't critical but it had to be stiff enough to act as a lever against the force of the brush spring) and cut four 1 1/2" long 'rods'. I stuck each rod into one of the brush holders on the end cap, with the brush slightly preloaded against its spring. Each rod would serve as a lever to hold the brushes in place, against spring pressure, in order to get everything back around the commutator. You can see the three of the rods, one at 12:00, one at 3:00 and one at 6:00 sticking out of the brush end cap in the photo below.
With a thumb on one rod and a finger on each remaining rod, I could squeeze all four rods and their brushes towards the center and managed to pop the brush holder cap with its spring loaded brushes back onto the commutator. Once the brushes were back on the commutator, I pulled the rods out.
I screwed the starter pieces back together and mounted it back on the engine. The battery spun the starter just fine and the engine started. The starter motor has worked flawlessly and started the engine well over a dozen times over the past three weeks, so it looks like a good fix.
Six years of northern Illinois spring and fall days when moisture condenses on any metal part at ambient temperature (cold storage in the garage) just locked all the moing the pieces up in the absence of lubrication.
If you run into the same situation, be every sparing when applying lubrication and make sure that any oil goes only on the helix shaft. Use as little as possible. The pinion is driven by two cone shaped friction pieces and any oil that gets on the cones will allow the cones to slip, so the starter will run but the pinion won't drive the flywheel if the friction cones slip because of oil on the cones.
