The Stovebolt Site Forums The Shop Area The Electrical Bay starter won't turn engine, and won't engage flywheel unless polarity is rev

One possibility is that the starter may have the wrong drive installed, it has to be set up as positive ground to engage the engine but it doesn't have enough power to turn over the engine.

I'm guessing it has a motor wound to have maximum torque in a negative ground setup but, has a drive that engages in the opposite direction.

If I hook it up with negative ground the starter motor spins freely because the clutch in the drive is being turned the wrong direction.

Is there something I could be missing? I'm jumping it with the dual batteries from my diesel, and 4ga. booster cables so I think I'm getting enough power, I've also tried multiple ground points including right on the but of the starter so I should be getting a good ground.

The truck is an early 40's Chevy COE.

Hy shortnose_rat, as far as I know starter motors turn in the same rotational direction regardless of electrical polarity hookup. Could the engine be just too tight to turn over?

A starter cannot turn backwards with reverse polarity unless it's got permanent magnets insteasd of field coils. GM didn't start doing that until the late 1980's, and then only on a few vehicles.
Jerry

I can spin the motor by hand so the starter should be able to move it.

I never knew that about starters, but I guess I've never had a reason to reverse polarity on one.

I thought I had it spinning in both directions on the bench, but maybe I better pull it out again and double check.

Problem solved, thanks for your help everybody!

It turns out the drive was worn out on the starter, I thought it was good but then I had a pro look at it, and I was very wrong, Haha!

Thanks for the update- - - -quite often we're left hanging, wondering if our comments helped out!
Jerry