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MG MGB Technical - How to bench-test a starter?

I'd like to know the safe and correct way to bench-test an MG starter. I have a plug-in battery charger to provide a 12 volt power source. First I fasten the starter to something solid. Then, the red line of the source I attach to the large terminal on the back of the starter. Where do I put the black line from the source?
M.E. Whalen

The charger will only put out a few amps. You need a 12V battery. Just connect across the terminal and ground the case to the other pole. Hold it tight in hand or in a vice and watch the pinion throw out.
Art Pearse

You only need a few amps to do a simple go/no-go test on a starter. It only takes hundreds of amps when it is cranking an engine. However a charger usually outputs pulsed DC so a battery *is* best as it is real world. I've spun a starter on the bench just with a length of flex. It did get a bit warm, but that is all. It doesn't need tying down either, there is not that much torque to turn the case as it is much heavier than the rotor. It doesn't even matter which way round you connect the leads, starters are not polarity sensitive, they are not changed when changing the polarity on a car.

If you have a early inertia starter there is only one large terminal, one lead goes on here, the other on the starter case, it will (or should) spin straight away, and the pinion should move towards the motor, i.e. in and not out.

If you have the later pre-engaged terminal there is a large terminal and either one or two spades, depending on whether it is chrome bumper or rubber. On these one is the solenoid operate terminal, usually a standard-sized one, and the other is the coil boost terminal, usually smaller. You can test the solenoid and the motor separately. To test the solenoid connect the leads to a spade and the body. If you have used the solenoid operate terminal the pinion will move out, but the motor won't turn. If you have used the boost terminal nothing will happen. Then connect the battery to the large terminal and the body, and nothing should happen. Now bridge the large terminal to the solenoid operate terminal, the pinion should move out, and the motor spin. If you have the boost terminal this should now show 12v with respect to the body.
PaulH Solihull

This thread was discussed between 08/03/2013 and 09/03/2013

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