So let's talk starters. These engines are known for being difficult to crank. I don't think there is any one reason but complaints are common. Apart from sounding pretty lousy, it would often get stuck on a compression stroke sometimes requiring another hit of the key. It has become annoying and as the weather gets colder, and especially as I talk snow blowers, I need to fix this. It's not right. Battery was 12.8V btw...which is fully charged.
Aside from cables, the only other factor is the starter itself. To rule out major cable issues, I did a voltage drop test on my cables. First I did the positive, battery terminal to starter cable bolt. Like 0.8V max when cranking. Not great but serviceable. On the ground I think it was similar, battery cable to engine block. Given that the starter has begun sounding pretty bad, and especially worse after I washed it a few weeks back, I decided the starter would need some kind of attention.
I found a guy on a forum somewhere (or possibly Youtube comments) who claimed every single Briggs opposed twin starter he's taken apart has basically been dry, as in dry bearings. My starter sounded like dry bearings so that was a possible match. The guy claimed they are super easy to take apart, and he's never had to actually replace one. Encouraging. So I embarked to pull mine off. Unfortunately that was a little tricky. There's one bolt hidden under the flywheel so that took patience to get. I also had to remove the main tin and the left side head tin but that's just bolts so whatever.
Finally I got it out and brought it over to my vice. There are two main steps to disassembly:
1) Drive out the roll pin on the shaft to pull the bendix and gear off. A punch and hammer is all it takes...
2) Remove the 2 long bolts that sandwich everything together. Just remove the lower bearing/brush holder and it all simply comes apart.
And what do I see? Some SUPER dry bearings. Yikes.
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Brush holder all in a pile. Brushes had plenty of life by the way. Original starter by the looks of it.
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Rotor. Don't lose the washers and stuff.
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Housing with permanent magnets.
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Next I basically cleaned everything off. First I started with contact cleaner but moved to carb cleaner, being careful not to get it on any of the electrical parts. I cleaned the shaft where it rides in the bearings as well as the commutator (still with contact cleaner). I didn't know what grease to use so I used wheel/chassis grease and lubed the bearings and rotor shaft.
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Now for the fun part: the brushes. I knew the theory (find something small to stick through the brush holder to hold each brush back for reassembly). But it took a bit of playing around to find what worked best. Ended up with two 3p finish nails per brush. I did one brush, held it with one hand while doing the opposite brush, then somehow managed to ziptie that pair. Then I moved to the opposing pair. Kinda tricky but it worked.
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Brush side. You can also see that I packed the end bearing with grease.
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Close-up of the nails. Just had to make sure they were pried tight so as not to interfere with the commutator.
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After that I just sandwiched the housing with the brush holder cover. Once I got it situated, I started the bolts, and then removed each set of nails. I heard the brushes spring/click right into place. Perfect. I also greased the Bendix and gear pretty well.
Installation on the machine is the reverse of disassembly...and be sure to wire brush or wire wheel metal to metal surfaces that need to conduct electricity. Like starter to head bosses and the starter itself.
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You can see the bolt hiding under the flywheel. If you are used to modern cars, this is hardly a challenge, though is a bit tight. I am sure a Briggs manual would say to remove the flywheel. That's unnecessary.
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So greasy. By the way, I think the starter gear is plastic. It was starting to get a little chewed up but will probably survive a long while.
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Don't forget to reattach the cable. My machine even has a protective boot (and it's still there).
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All that reassembled I turned the key and...the motor engaged but the gear did not engage the flywheel. It threw excess grease everywhere. I tried again and it worked perfectly. I guess it threw off what it didn't want.
With that working, I cleaned the battery cables just for good measure. They were not bad but freshly sanded terminals are always better.
Then I basically drove it around, shutting it off and restarting. It cranks quietly and as quickly as I think it did when it was new. It's so satisfying. When warm it starts up at a full idle just like a car, with a little idle flare before settling down. It did that before but it barely has to crank now and does not get stuck on a compression stroke.
So my options were aftermarket starter, Briggs OEM or this. There's nothing more farmey than taking a starter off, taking it apart, greasing it, and putting it back together only to have it work almost like new. If I got a new brush housing with bearing, and pressed in a new upper bearing, this literally would have constituted "rebuilding" the starter.