how do you bench test a starter motor.

You can check it spins with a set of jump leads and a battery.

Black (-) to case

Red (+) to larger of the two studs.

Bridge a wire from little stud to the big one.

Mount it in a vice because it will kick.

cheers

Ok thanks, Big-wasa

the torque is
efffing huge so tie it down like ^^^ said.

also the spark from the battery will be enough to scare you!!!

also make sure you can release the cable i.e. if using jump leads, do not calmp the second one but just touch the terminal.

picImage deleted by owner

don't forget to ground the starter as well. Normally the starter is bolted to the gearbox that is bolted to the engine that is grounded to the chassis that is connected to the battery earth.

(ok, i admit it took me 10 minutes to figure it out when i was first looking at my started in the car).

it is also best if you can load test it against some thing as if it has a weak field/ armature if may spin fine in a vice but no good when trying to turn the engine. I used to use the free end of a wooden handle hammer to force into the bendix to put a laod on it.
As you can tell may be best to have someone else help you touch the wire to the stater motor whist you do this.