Bench testing a starter

[Fred Mc]

I am replacing the 12v starter in my GM PD4106 with another starter and want to check to make sure the new starter works and turns the correct direction. Its a lot easier now than having to remove the starter again(horrible job).

Anyway I tried connecting the battery to the big positive and negative studs on the started but nothing happens. I don't want to damage it by connecting cables wrong nor do I want to tear my arm off as I expect these starter have a lot of torque.
Can anyone guide me on this.

Regards

Fred.

[Fred Mc]

Anyone??

[PP]

I'm sure someone with experience like Geoff or Cliff will chime in soon here, but it was smart on your part not to try to hold that animal down while connecting juice to it. A lot of torque is an understatement  Good luck, Will

[bevans6]

Sorry, not Geoff or Clifford, but anyway...  Clamp it in a vise, the torque might try to make it spin a bit.  Assuming its a MT-40 starter, there are four big 1/2" dia. threaded lugs, two on the solenoid (the small cylinder bolted on top of the starter motor body), two small lugs on the solenoid, one big ground lug on the end of the starter and one big lug directly under one of the solenoid lugs and connected with a strap.  The two small lugs control the solenoid on and off, one goes to a relay switch and the other goes to the ground lug with a wire.There are two big lugs on the solenoid itself, one has a strap to a lug on the starter motor and the other is bare - it will get the big positive voltage cable bolted to it.  

Take your battery and your jump cables and connect positive to the lug on the solenoid that is bare (not the one with the strap down to the starter itself), and connect the ground to the ground lug (big lug on the face end of the starter).  Then take a jumper wire or a screw driver and jump from the big positive lug with the positive jumper cable to the small solenoid lug.  Make sure there is a jumper wire from the other small solenoid lug to the big ground lug.  That causes the solenoid to move, pushing the pinion out and closing the big switch inside the solenoid to power up the starter motor.  It might spark a bit, wear gloves, etc.

Brian

[luvrbus]

My advice is take it to rebuilder in your area,where they can circuit lock torque test the thing, it may spin it's @$# off in a vice and not spin the engine. Those GM starter are to hard to remove and replace to even chance a bench test IMO " horrible job" doesn't even start to describe it  

[Fred Mc]

Thanks Brian.
I wired it up like you suggested and just got a small spark but no action.So I tried the one I took out of bus (which started it a day ago) and got the same results. I then tried different batteries but same result.So tomorrow I will take it off to a rebuilder to get them to check it out.

Thanks

Fred