Starter Grinds (but only sometimes)

[MMH]

On my 4500, about every 20 starts or so my starter grinds. When this happens it seems as if the starter gear starts spinning before it is fully extended. I immediately release the key and then try to start again. Usually if it does it once, it will grind two or three times. I had the starter at a starter/alternator shop and they said that everything checked out OK (the starter, solenoid, bendix, etc. - they were thorough). The even ground the teeth on the starter to give them a little bit more lead in. The starter still does the same thing. I looked at the gear on the flywheel and do not see a damaged spot that would keep the starter gear from not properly engaging.

I am worried that if the starter continues to do this that I will damage the gear on the flywheel. Anybody have any suggestions as to what else to look at or do?

 

[beenthere]

There are apparently several gears that may be involved.. if this schematic of the 4500 is like yours.

The plunger and solenoid would be my thought. Maybe connection of the cable to the solenoid or the other end..

 

[Wagtail]

When you took the starter to the shop, did they replace both of the brushes?

They do wear down over time and a broken/uneven-worn brush can produce a grind, especially if it's in a particular 'sweet spot'.

 

[MMH]

When you took the starter to the shop, did they replace both of the brushes?

They do wear down over time and a broken/uneven-worn brush can produce a grind, especially if it's in a particular 'sweet spot'.

I will check. Why would a worn brush produce a grind?

 

[Wagtail]

I will check. Why would a worn brush produce a grind?

Because the electrical motor's armature may be "chittering", or the brush is so worn down that the metal plate or wire is impacting the armature.

Laymans term; the motor doesn't know whether to turn one way or the other