Mag 20 starter spins but doesn't engage ring gear
 

Just like the title says, I have a mag 20 that the starter spins, but does not kick the gear out to engage the ring gear. The starter was supposed to be serviced by the dealer where I bought the 2072. He is in the electrical repair business as well as being a mower dealer, but I personally wouldn't take anything to him. It has done this before, but I could always just quit cranking and try again and it would crank just fine. It also acts like it doesn't have the power to crank the engine very fast. It has good cables, I have used a known good battery out of my 1450 and even jumped it off of my 1782 (with a car size battery and 40A alternator conversion) without any better results. Am I in for replacing the starter or is there something else I need to be checking.
Thanks,
Geoffrey

The bendix on that starter is just a screw. In other words, when the starter kicks in it literally "screws" the gear up to the flywheel. Most of the time some lube on it helps. WD-40 to free it up, oil or light grease to make it stay that way. It's better to do this to a removes starter. Bad news is, they're a PITA to remove. If it's not cranking very good, it may be on the way out, which would also make it not jump out well. If you've hooked it to a car battery without better results, you either have a bad connection or a worn starter. FWIW, I've heard about a million people say they have good connections. Then they buy a starter and it doesn't fix it...... and find out they had a bad connection. I'd be 100% sure it's not a bad connection before purchasing a starter. :beerchug:

My father's 1862 had a similar problem. He said the battery and connections were good as well. When I looked at it, I found the battery was 9 sheets to the wind, and the negative terminal was all corroded with just a few strands left to make the connection. The starter was not getting enough power really spin up with a snap to push the bendix out there to engage the ring gear. A new battery and cable ends, had it starting with no problem.

See...... perfect example! Thanks Frank! :beerchug:

Ok, I'll double check the cables tomorrow and check the voltage getting to the starter.

I did see on another site that the poster had to extend the bendix all the way and spray cleaner on the drive to degrease it. I hadn't thought of it, but the dealer said he lubed the starter. It may just be that it needs cleaned. I really doubt it, but it's worth a try.

You should also take the starter apart and clean it. Check arm,brushs,comm, there's a writeup from Matt G on this somewhere. Mike

STOP! Do not take the starter off. I had the exact same problem on my 1811 and all I had to do was to remove the side panel, pressure wash the Bendix drive and at the same time with a long screw driver move the gear back and forth while spraying with the pressure washer. Then I did the same thing with WD 40, moving the gear back and forth while spraying it with WD 40. That was over two years ago and no further problems. That gear and screw system get a lot of crud in it over the years and that makes it not go to the end of its travel so it never reaches the engine starter ring. It is important to move the gear back and forth to clean out the groves of the screw. It is not the easiest thing to reach but it is a lot better than taking the starter off. It may turn out that you do need to remove the starter but do the easy things first.:beerchug:

Ok, all the wires and connections DO look good and from the battery to the starter I'm loosing not quite 1 volt. I don't think that would cause it to not work.
While my Dad turned the key for me I watched the bendix. It just kicks out a little ways and returns to it's "home position" within a couple seconds. I'm thinking it may be the dirt problem in the bendix.

I had one that acted up like yours. I shot some oil on it out of a aerosol can. It's been okay now for 2-3 years. I had to do it twice best I remember.

Sometimes those motors will get dirty inside. Not just the Mags either. K series, Vanguards, outboard motors, automotive starters, etc.

When the armature bushings run dry and the commutator and brushes get dirty, even though they are not worn to the point of refurb, the starters will spin slowly and either the Bendix won't engage or the starter won't turn the engine over. Many times all it takes to fix a starter motor of any kind is to just blow it out, clean the mica out between the commutator bars, clean the commutator/brushes and lube the armature bushings and the starter will perform almost as new.

I have been thinking of trying this on the 1811. But with brake cleaner, compressed air, and some graphite if i can get it in there. If that doesn't cut it I will break out the PW. :beerchug: