Feedback Score: 0 reviews
Join Date: Jan 2011
Location: Smack in the middle of Illinois
Thanked 294 Times in 289 Posts
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.