starter motor self destructs

[Henry Weber]

My vessel is a 1977 Hunter 30 with 12hp Yanmar YSB12 single cylinder diesel.Every so often the starter motor stays engaged after the diesel starts. If you don't catch it and shut down the engine, the starter motor windings start burning and self destruct. The pinion gear of the starter does not retract from the ring gear on the flywheel.After the diesel engine starts to run, the starter motor is driven at some horrendous speed and shortly starts to burn. The first time the starter burned up, I thought the ignition/starter key switch was sticking in the start position. I replaced it. The second time a starter burned (a year later), I bought a heavy duty marine push button (momentary on ) switch with rubber weather guard to replace the key switch for starting. This was to make sure the solenoid coil current turns off after the engine starts. It has been only three weeks and the third starter burned yesterday.Does anyone have a clew why this is happening?Thanks for any help.Henry

 

[Cecil]

My Two Cents Worth

Henry,I`ve got a 75 H30 with a YSE 12,I would inspect the starter ring gear for burrs/damage ,sometimes that can cause the bendix to "hang up",also make sure the bendix has the correct number of " teeth".When checking the ring gear, make sure to check 360 deg, maybe just one short area bad.In some cases low batt voltage will weld the starter solenoid contacts keeping the starter engaged w/o batt voltage to the "s" post. Hope this helps, let me know what you find Cecil

 

[john renfro]

two more cents worth

hello henry, also check the clearance between the flywheel teath and the teeth on the starter, you may need to shim the starter so that the starter teeth do not engage so deeply. i once had merc 70 hp outboard engin that if the starter was not used for several months, the pinion shaft and gear would dry out and not disingage from the ring gear. a little grease on the shaft would fix it.john