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1978 Mercury M900 starter question

R

ryans01z28

Contributing Member
About a week ago I tried starting my boat and the starter wouldn't engage the flywheel so I tapped on the starter with a hammer and then it worked. I tried to start it again and same thing happened by the 3rd go around the started completely stuck wide open and I couldn't get it to shut off and some of the wires started getting really hot so I had to disconnect the battery. I then ordered a new started and a new relay. Tonight I went to try the boat with the new parts i put in and it fired up numerous times so off to the lake I went with my fixed boat. I put the boat in the water and went to fire it up and when I turned the key the started wouldn't engage the flywheel again. all it would do is free wheel without the started drive assembly contacting the flywheel! Off came the engine cover and I gave the starter a light tap and off it went. This is continuing to happen and I don't know why. Does anyone have any advice for me?
 
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I suggest spraying some penetrating oil in the shaft the Bendix ends moves on. Gotta be sticking.

Jeff

PS: Does the motor spin over FAST when it does engage? A low (or messed up) battery will sometimes cause that.
 
some of the wires started getting really hot so I had to disconnect the battery.
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If the cables are 1978 they may be high in resistance thereby reducing the available current to the starter Agree w/Jeff about the battery
 
I just sprayed some liquid wrench on it and it worked for about 5 times them the same thing happened. Ill test the battery or plug my onboard charger in
 
The batt voltage is 12.50v. When I hit the key it dropped to about 10volts. I hooked up my onboard charger and the voltage is at about 14.20. I hit the key and it drops to 13.30v and still doesn't engage the starter to the flywheel. If I tap on the top of the starter and turn the key it works, the next time I turn the key it doesn't. Current at the starter when I hit the key is 12.75ish
 
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Gotta be a burr or something that's hanging the Bendix up. I suggest taking it apart and doing a bit of filing/ sanding.

Jeff
 
Just F.Y.I..
Never strike the side of the starter with a hammer (or anything) You will destroy the internal magnets.. It appears you need new brushes for your starter. You can find kits online. While you are at it, replace the bendix, its due with that year motor. Also, check you starter solenoid.
 
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