Make sure you are using a starter that is made for the number of teeth on your flywheel. They make two different flywheels.The same starter will work on both but not for long. Check the tooth number and make sure you have the starter to match.I have been down this road. Just my 2 cents JOHN

hey ant...
are you using a starting battery with enough cca? merc does not recommend deep cycles for the task. i'd even steer clear of dual purpose...try something in the 800 cca range (it will carry an even higher mca rating. it could be like any other electric device...too little juice screws things up...
just a thought...
c

When you say the starter is going bad ? Is it destroying the teeth in The bendix or is the starter motor going bad? If its tearing up the gear it could be an alignment problem or a Voltage problem .... you need to check the Voltage AT the starter when you crank it over .... I think it needs to be 9.7 volts ... I can check tomorrow ....

Its either alignment ....Voltage at the starter ( a bad Connection or cable) .... also I have seen the starter grind when the bolts get loose... you sure they are the right length bolts? ........ Check the Flywheel teeth also as FenderJack stated .... m

Thats what my friend Rich Zul thinks its a grounding problem, im gonna try to add another ground to the starter mount bolt.

the teeth on the starter look fine, its just strange how a new starter works fine for a little then starts to grind,if i am loosing ground will the bendix kick back and make it grind under a load?

Thanks John,I guess its gonna be a pain in the ass to check the # of teeth on the flywheel in the boat, do you know the diff. between the two starters?

You need to monitor voltage and ground at the starter when its cranking the engine. If the engine is advanced a little it will fire against the starter, pulling more current and dropping voltage, as voltage drops the solenoid backs off and the drive gear disengages, spins up, re-engages, repeat, all in seconds.

I was eating starters in my 540's and I solved it by going with Hitachi's, there almost double the torge and dont use the nylon gears inside, also their not that much more than merc's. The only problem is that their a straight bolt pattern, not offset like the merc's, my block is drilled for both,Powermaster makes a offset pattern that is close to the hitachis in torque..http://www.jegs.com/webapp/wcs/store...0002&langId=-1

I did not see any marine starters under that link?

Or should I say Coast Guard Approved.

their not ! grap a can of paint and some stainless nuts and their marinized.. but what would you rather do, keep replacing or be done with it..the starboard motor on my cat you have too pull the motor to change it,so I got sick of it real fast.. on the stocker's all you have to do is hang a start one time or a backfire and their toast..
heres a link to the discussion on this before. http://www.offshoreonly.com/forums/s...d.php?t=189243