Determining if a Starter is Bad?

[chesbaycruiser 82]

After some significant surgery to get down to it, I removed the starter from the Briggs on my little Toro Wheel Horse 8-25.  The plastic throw-out gear is clearly shot, which confirms the source of the nasty sound when the starter was engaged.

I don't have much experience servicing starters, so my question is this:  When I turn the shaft of the starter by hand, it is not a "smooth" rotation, but more a "bumpy" one.  (That's not really an accurate description, but the best analogy I can come up with).  I'm thinking it's just a result of the resistance/attraction of the magnets inside.  When the starter was on the tractor is was clearly spinning when engaged.  

Am I correct in my assumption that when you rotate a brand new starter, it does not spin freely, but there is some feeling of "bumps", or maybe "evenly spaced resistance" is a better description?

If this was a side shaft Kholer I'd just buy the gear and re-install the starter and then if problems persisted, I'd pull it back off and swap it out.  But since getting the starter off on this thing was such a process, I really don't want to have to get at it again.  But I'm also don't want to buy a whole new starter if all I need is the gear.

I guess I'm just looking for some confidence.  Thoughts?

[Kai Thomsen 17]

Thats's normal. I think it's called "cogging effect"  in English. What you feel when turning the starter by hand is the attraction between the magnets and the stator/armature poles.

[chesbaycruiser 82]

Thanks Kai.  That's about how I figured it.

 

I purchased the gear this afternoon, along with some carb refurb parts.  Hopefully I'll get the whole thing put back together tonight, but fist I need to get my youngest son to his Eagle Scout Board of Review!  If all goes well, we'll have a second Eagle in our house tonight! 

[ARK 9]

Just a thought, while you have the starter out, look at the armature and the segmented copper commutator.  The commutator MUST be separated by insulation between the bars of copper and MUST be lower than the copper face.  If not take a shortened hack saw blade, you may have to grind the blade to fit between the bars, then cut out some insulation to lower it.  Check the armature for hot spots.  Re-grease bearings and test for sloppy misaligned fit.  The brushes should be checked for fitment and face angle to fit the rotation of the commutator.

Bench test with a load on the motor.

Also look at the field coils and magnet faces.  The coils should be clean, no loose wires or copper showing ( varnish insulation should be in tack. Magnet faces , no marks, no hits, evenly gapped and insulation paper if any, no rips, tears or wear.

[Rick_in_CT 156]

Chris,

 

Hope that the board of review went well for your son, and you have a second Eagle.  Ten years ago in march my son earned his Eagle.  Today he is an officer in the Navy, serving on a guided missile cruiser in Japan.  When we talk, we often touch upon things that relate back to a scouting experience.  It might just be that he was recently cold and wet on board ship, and we laugh about a campout that had similar conditions.  Lots of memories are made on the road to Eagle.  Hopefully you can sneak in the time for your starter tonight, but if you can't, we will understand! 

 

Congrats,

 

Rick

[Fordiesel69 199]

On a briggs starter, it is simple.  Magnets and bendix.  Those are the two major failures.

 

It should feel gritty, as you are feeling the permenant magnet poles.  When the magnets come unglued, they will rub the armature and you will hear / feel the drag. 

 

I would go with a new bendix assy, the new style that briggs had is much more robust.  They DO NOT get oiled or lubed in any way.

 

My GT-1642 used to eat the gears, until I got the new assembly. 

[chesbaycruiser 82]

Thanks for input guys!

In the end I figured the best thing to do would be to start off just replacing the $6.30 starter pinion gear.  I f that didn't do the trick, all I was out was a bit more time and a few more scraped up knuckles to pull the starter a second time.  That was evidently the right choice, because she spins over and fires right up without a hitch now!

In other news, I am happy to report that my son passed his Board of Review with flying colors and the paperwork is on it's way to the BSA national headquarters!  Very proud of Eagle number two!