Starter motor questions - rebuild

[Jezza_hr]

Hey guys.

I've had a few starter issues I've been trying to resolve today and after some troubleshooting I'm trying to narrow down if it's the copper connectors or something else.

I can get the magnet to move out the gear if I connect it to the opposing side of the motor (the side that usually has a rubber seal over it), but the motor itself doesn't turn. I have no issues moving the cog by hand if I pop it out.

Looking under the covers, one of the copper connectors looks slightly galvanised, but I wouldn't have expected this to make a difference if the magnet slides the cog out? Am I missing something

[jondee86]

When the solenoid moves the gear out, it also makes a contact to switch
power to the motor. So, if solenoid moves but the motor does not turn,
there are two possibilities...

1. The solenoid contacts are not making a connection, or

2. The carbon brushes on the motor are worn down and no longer
making a good contact with the copper commutator. This one can often
be temporarily fixed by giving the body of the starter a sharp crack with
a small hammer or similar tool.

This shakes the brushes enough to get then to move fractionally, and
make a better contact. Still needs fixing by replacing the brushes :wink:



B and M are the contacts that make to put power on the motor.
S is the small wire that supplies power to the solenoid.

Cheers... jondee86

[Jezza_hr]

Judging from what I've been seeing, the solenoid contacts are a more common issue than the brushes, but I was a little confused as to why the sliding mechanism would work but not the motor itself, since my assumption was they are both on the same circuit and one shouldn't work without the other, but then I guess one has to work to make the other function, since you don't want the motor turning without the slider being engaged first.

I've gone ahead and ordered a pair of new copper solenoid connectors as they're only £5 shipped from eBay. If that doesn't do the trick, I guess it will be the bushes.

Thanks for the help Jondee

[allencr]

Just put 12V to the other terminal(M in the diagram, that large terminal that goes into the starter motor) to see if it'll run. It also energizes the holding coil but it won't be strong enough to move the gear.

[Jezza_hr]

allencr Wrote:Just put 12V to the other terminal(M in the diagram, that large terminal that goes into the starter motor) to see if it'll run. It also energizes the holding coil but it won't be strong enough to move the gear.

That's what I tried. As you say, it slides the gear out but it doesn't engage the motor. I'm guessing the connector ( B ) usually provides a stronger connection to the motor to turn it when it's not worn.

I did pull apart the motor again last night and the brushes appear to be fine. They all sit firmly with little to no wearing down. So, that galvanised connector (no matter how minor it looks) must be the culprit.

[Apsogos]

very helpful article!Thank you