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There's basically three reasons a starter motor will spin without cranking the engine; 1) battery hooked up backwards (positive to ground), 2) bad starter drive (clutch between the starter motor and crankshaft) a common problem on abused engines that had infrequent oil changes and degraded batteries, 3) the starter motor shaft has broken or the teeth that engage the clutch gear have been stripped. There are other less common problems like the bolts holding the starter clutch to the flywheel are broken or backed out no longer holding the clutch to the flywheel, a loose flywheel and a sheared key or a broken crankshaft.

It's what keeps a mechanic busy - trying to figure out why something does not work :nerd:
 

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Discussion Starter #22
There's basically three reasons a starter motor will spin without cranking the engine; 1) battery hooked up backwards (positive to ground), 2) bad starter drive (clutch between the starter motor and crankshaft) a common problem on abused engines that had infrequent oil changes and degraded batteries, 3) the starter motor shaft has broken or the teeth that engage the clutch gear have been stripped. There are other less common problems like the bolts holding the starter clutch to the flywheel are broken or backed out no longer holding the clutch to the flywheel, a loose flywheel and a sheared key or a broken crankshaft.

It's what keeps a mechanic busy - trying to figure out why something does not work


Wow that's got me asking myself a million questions now


After trouble shooting and taking the rear case off and looking at the starter gears they don't look stripped at all i think it's a issue with the flywheel

I replaced the crank with a brand new factory crank shaft it spun nice and smooth but when I put the front case back on and tightened all the bolts the crank wouldn't turn as smooth it felt like It was getting stuck a tiny bit

I'm thinking I didn't secured the flywheel correctly
 

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Discussion Starter #23
There's basically three reasons a starter motor will spin without cranking the engine; 1) battery hooked up backwards (positive to ground), 2) bad starter drive (clutch between the starter motor and crankshaft) a common problem on abused engines that had infrequent oil changes and degraded batteries, 3) the starter motor shaft has broken or the teeth that engage the clutch gear have been stripped. There are other less common problems like the bolts holding the starter clutch to the flywheel are broken or backed out no longer holding the clutch to the flywheel, a loose flywheel and a sheared key or a broken crankshaft.

It's what keeps a mechanic busy - trying to figure out why something does not work

So after checking the flywheel it's spins nice and smooth now but the starter still won't grab the gears to spin it over
Why are the gears not grabbing?!
 

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Simple - the gears are perpetually engaged - the starter motor spins the gears - the large gear behind the flywheel has a hub that runs inside a one way clutch - the large gear is supposed to bind (lock up) when the starter turns the gear counter clockwise - when the engine starts, it runs faster than cranking speed, so the starter gear unlocks and the one way clutch is no longer driving the flywheel. If you hit the starter while the engine is running, the starter motor runs, but nothing else happens as the engine is running faster than the starter motor turns the starter gear.

When the one way clutch is worn out or damaged, the large gear will spin without locking in both directions - both the large starter gear with hub and the one way clutch need to be replaced to fix the problem and the oil needs to be changed regularly to prevent the clutch from wearing out prematurely.
 

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Discussion Starter #25
Simple - the gears are perpetually engaged - the starter motor spins the gears - the large gear behind the flywheel has a hub that runs inside a one way clutch - the large gear is supposed to bind (lock up) when the starter turns the gear counter clockwise - when the engine starts, it runs faster than cranking speed, so the starter gear unlocks and the one way clutch is no longer driving the flywheel. If you hit the starter while the engine is running, the starter motor runs, but nothing else happens as the engine is running faster than the starter motor turns the starter gear.

When the one way clutch is worn out or damaged, the large gear will spin without locking in both directions - both the large starter gear with hub and the one way clutch need to be replaced to fix the problem and the oil needs to be changed regularly to prevent the clutch from wearing out prematurely.

So the starter is supposed to spin clockwise? Or do I need to replace the starter to?
 
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