3.0L Starter motor soleniod help

[Mark RSA2AU]

Hi Guys

I have a 3.0lt 135hp Merc in my 1999 180 BR. this week end the ignition key failed and did not return the key back to the "Run" position from "Start" position. As I was skiing behind the boat I did not see or hear anything but since this the starter is playing up and I am assuming this was the cause as the battery is perfect and everything was working untill that moment. I have replaced the ignition switch already but the starter is still doing the same thing.
:smt089
Whether we use the ignition key or short out the starter at the connections it does the same. The starter motor cranks and spins every time. It engages the engine for a split second like it is making contact with the flywheel then spins off. Some times it holds on for just long enough to start the motor but this is now a 1 in 10 chance. Turn the key and you hear it spin, connect, crank for a split second, then wirrrr... it releases and continues to spin.

Can someone help diagnose?

 

[CliffA]

could be damaged or missing teeth on the starter or the engine flywheel....i had this happen to a car once...it had some missing teeth in the flywheel....it just depended on what position the engine was stopped as to if the engine would start again...if the section of missing teeth on the flywheel was positioned in front of the starter gear the starter would just spin....if i left the tranny in gear and rocked the car a little the engine would turn over slightly and move a section of the flywheel that still had teeth in front of the starter gear...then the starter would grab the flywheel and turn the engine over...

cliff

 

[Steve Craig]

Ignition key in START circuit operates only the solenoid at the starter. (Other things on the boat yes, but for this discussion only the solenoid.) Solenoid acts like a big plunger. When it's energized it changes position & closes two contacts between the battery & the starter windings. If you hear the starter turning every time I would suspect the solenoid is OK.
Broken teeth on the flywheel as Cliff suggested would be my first guess.
Anything like my boat I dread the day the starter fails as I fear it may mean pulling the engine to get at it.

 

[mwph]

Did this just start happening all of the sudden? Any work with the starter done recently?

I hate to hear all this talk about broken flywheel teeth. Just for the sake of optimism, any chance the sarter has loosened up & has slightly fallen away?

 

[Mark RSA2AU]

Hey mwph

Everything was working perfectly untill the ignition switch failed and I suspect kept the starter motor engaged while running. since then the starter spins but only engages for a split second and then releases, no grinding noises no slipping teeth that I can hear. The starter motor gear might have overheated and caused some dammage, or the soleniod has also overheated and needs a clean out/ repair to ensure it keeps the gear engaged.

The starter motor is in a horrible position almost underneath the motor. I will need to remove the rear seating and framework to get to it, but I will pull it out this weekend to have a look.

there is a small hole at the flywheel that I can shine a torch into and I will rotate the motor to check the flywheel teeth as well.

 

[mwph]

The starter motor gear might have overheated and caused some dammage, or the soleniod has also overheated and needs a clean out/ repair to ensure it keeps the gear engaged.

Thats what I'll hope for. Good luck, keep us posted.