4.3 OMC not cranking (yes, the battery is fine)

[Liquid_force]

Ran fine all summer. Putting it away last fall I couldn't get it to crank, even while being jump started. Didn't have time to fiddle - assumed it was something simple.

Got it out this spring to get it ready again, still won't crank.
Installed a known working battery, still won't crank.

Terminals and wire connections have been cleaned - no corrosion, shiny metal.
Starter is 2 yrs old.

We can hear the starter engaging the flywheel when turning the key, but the crank doesn't turn at all.

Crank turns manually w/expected resistance.

we're in the process of checking all the wiring at the starter.

Not sure where to go next.

Suggestions?

 

[Gary H NC]

Re: 4.3 OMC not cranking (yes, the battery is fine)

Pull the starter and have it tested...
Did you try jumper cables directly to the starter?

 

[Liquid_force]

Re: 4.3 OMC not cranking (yes, the battery is fine)

ok - I unbolted the starter from the engine, but left it connected electrically - grounded the case.

the starter gear engages, sliding up the shaft as it should, but it doesn't spin. I guess I can assume mechanical starter failure?

 

[JustJason]

Re: 4.3 OMC not cranking (yes, the battery is fine)

Do a voltage drop on all your starting circuits... If the drop test checks out you have a bad starter.
But if it still won't spin with the starter off.... then it's definitely bad. When you go to install a new one do the drop test to make sure it wasn't voltage suffering that killed it.