What's wrong with my starter?

[Waternut]

It worked great 3 weeks ago. It kinda worked last night and I figured I just had a dead battery so I charged it and today it hasn't worked yet. I pulled it apart and cleaned everything up as it was really disgusting.

The brushes still have loads of life, the commutator is in good shape, and now everything is nice and clean but it still won't turn. I've tried hooking a battery directly to the starter and nothing happens.

 

[Matt_E]

Does it spin freely by hand?

 

[Waternut]

It does spin freely by hand and the contact on the outside of the case sends 12 volts to the first brush.

Well let me rephrase...it spins smoothly with pliers but I can't turn the shaft with my hand.

 

[Matt_E]

Then it's toast.
The needle bearing is gone.

 

[Waternut]

So is it grounding against the bearing? Is that the deal?

 

[Matt_E]

No. The bearing is bad, which means the starter cannot spin.
If you can't spin it by hand, then the motor can't do it, either.

 

[Kaveman]

If you have an old starter with bad brushes then swap the nose and armature into the one that won't spin. You should be good to go.

Most Yamaha, Kawasaki, Polaris, Tigershark and some Seadoo starters will have the same nose, armature, magnets and main body. What makes them model specific is usually the tail housing where the brushes are located.

 

[Waternut]

I think I need to explain a little better. The reason I can't turn the motor by hand is because there is so much pressure on the brushes. The armature turns freely and very smoothly through the needle bearings.

I have noticed that there is a hefty voltage drop from the connection on the outside of the case to the actual brushes and comm. The battery measures 12.7v and the voltage on the comm measures 3-4v. Maybe that's all the problem is.

 

[WFO Speedracer]

I think I need to explain a little better. The reason I can't turn the motor by hand is because there is so much pressure on the brushes. The armature turns freely and very smoothly through the needle bearings.

I have noticed that there is a hefty voltage drop from the connection on the outside of the case to the actual brushes and comm. The battery measures 12.7v and the voltage on the comm measures 3-4v. Maybe that's all the problem is.

Yes thats where the problem is ,there is no way it will work with that kind of voltage drop

 

[Waternut]

Got it... The bars inside that touch the stud were worn and they were barely touching. I put a washer inside to extend the stuf far enough to touch the contacts and it works great.

Thanks for everyone's help.