Spinning starter, but doesn't engage

[afc208]

I have twin 150 saltwater normal carbed Mercs with 80 hours. One engine starts perfect, the other the starter spins but doesn't engage. Twin batteries are fully charged (same thing happens no matter which battery I choose). The only other interesting fact is that I lost the original key to the non-starting engine and was given an OMC key that my mechanic stated was fine. This is when the problem occured. My shop states they started the engine with the new key and it was fine at the time. Of course, they will be happy to look again for a small fee! Any thoughts?

 

[ob]

Re: Spinning starter, but doesn't engage

I'm no merc expert but i think a key would either make or not make the ignition switch.Double check connections to starter motor to insure tight .you can also manipulate bendix gear manually to see if it will twist up toward flywheel.Perhaps it's just stuck.Is starter bendix turning?

 

[afc208]

Re: Spinning starter, but doesn't engage

OB:<br />Drive gear is turning fine. How hard should I pull on the gear to see if it comes up, I can't get it up buy pulling on it with my hand. Should it be easy to get up or do I need to "pry" it?

 

[ob]

Re: Spinning starter, but doesn't engage

You may need to pry it slightly in a turning direction as opposed to straight up .Should move freely toward flywheel.Check it on other motor .

 

[petryshyn]

Re: Spinning starter, but doesn't engage

as OB says, it should move up and down freely. Compare it to the other starter as he suggests. If its tight, free it up by applying penetrating oil to the shaft. Once free, lube it with a light engine oil, above and below the drive, on the spline as well...<br /><br />

 

[afc208]

Re: Spinning starter, but doesn't engage

ob:<br />Appears to come up fine when drive gear turned clockwise, but I can't get it to come up counterclockwise, which appears to be the direction needed to crank the engine (meaning the flywheel needs to spin clockwise). The good engine flywheel cranks clockwise.

 

[ob]

Re: Spinning starter, but doesn't engage

Are these motors not opposing rotation?Should only come up in one direction. was this starter changed out by any chance?Hey schematic ,Nice snapshot.Srarter rotates in opposite direction requred to turn bendix to get it to move toward flywheel

 

[afc208]

Re: Spinning starter, but doesn't engage

Great photo, that's it. It lifts up when I turn the drive gear clockwise. It appears that it must turn counterclockwise though to get the flywheel to turn clockwise, thus cranking the engine. I can't get it to turn and come up that way.

 

[afc208]

Re: Spinning starter, but doesn't engage

ob: Serial # search from Merc shows no factory work performed on them. They are not counter rotating, at least nothing on the engines implies that. Also, the flywheel on each engine is the same, meaning if I had to use a starter rope the direction I would have to wrap the rope would cause both engines to crank clockwise.

 

[ob]

Re: Spinning starter, but doesn't engage

If it is freely moving up toward flywheel by hand and still won't engage when cranking starter bendix is stripped or there is insufficient voltage to starter motor.

 

[afc208]

Re: Spinning starter, but doesn't engage

OB: Could the battery start one engine and not the other? <br />What would have been done to strip it after only 70 hours?<br />Looks like a new starter is in the works.<br />By the way, thank you for all your help.

 

[petryshyn]

Re: Spinning starter, but doesn't engage

As OB says, low battery certainly will do it!<br /><br />Check the voltage while cranking!!<br />Anything over 9.6v while cranking is enough. If you have over 9.6v, its NOT a battery/cable/soleniod problem....<br /><br />

<br /><br /> Is it possible that somehow the battery leads got switched? This will cause that as well....<br /><br />>

 

[ob]

Re: Spinning starter, but doesn't engage

Not likely on first question.I don't quite know how to word this question so I'll just ask,Does rotation of starter seem strong and not gimp when attempting to crank?This could rule out defective bendix and points back to weak connection ,possibly through starter solenoid.if it's not too much trouble you could attempt to verify by swapping solenoids.

 

[afc208]

Re: Spinning starter, but doesn't engage

Starter spin really doesn't seem to have any "balls", you may have hit on something there.<br />That's what's good about twins, replacement parts for testing are available cheap! I'll go ahead and check all the voltages and swap out the solenoid.<br />Schmatic, where do you get great illustrations?<br />Thanks very much.

 

[petryshyn]

Re: Spinning starter, but doesn't engage

afc208<br /><br />The above test will quickly steer you to the starter motor, or a battery/cable/solenoid issue. I recommend doing it first. <br />(until then, you're only guessing!)<br /><br />(I draw the images in Microsoft Powerpoint)<br />

 

[Yepblaze]

Re: Spinning starter, but doesn't engage

I'm a-wonderin ifin ya got deep cycle batteries instead of regular old crankin batteries. Many times of late I've seen the issue you describe being caused by a deep cycle battery and it's appaernt surface charge that just won't give it that initial fast spin needed to engage the bendix well. Try a starting only battery.

 

[72 mako 19]

Re: Spinning starter, but doesn't engage

i had the same problem on my motor. bought a multimeter to be sure what the problem was. it was the voltage. Too low; about 8 something volts only. Worked my way back from starter to batteries as manual suggested. the readings were very unstable on the starter and solenoid part. My mechanic said the Starter was 'dying', since it is old and has never been replaced or opened; he suggested that I replace it. So, I changed the positive wire going to starter plus the starter and solenoid itself. Since, I am replacing the starter, might as well replace the solenoid. Boat has been working fine ever since. You could probably just replace the insides of the starter; but for a sure bet, replace the whole starter if it is the problem.

 

[Navigator]

Re: Spinning starter, but doesn't engage

You've probably checked this already, but when I had a similar problem a while back, it was because there was corrosion inside the battery ground wire under the plastic casing. I have no clue how it got there, but it was choking the amps. The voltage tested fine, but when it tried to draw the big amps to crank, it just couldn't do it. I replaced the battery cable and she hit hard on the first crank. I spent 4 weeks dinking around with it trying to figure it out so I know how you're feeling. <br /><br />Just a thought you might want to check.<br />Nav

 

[afc208]

Re: Spinning starter, but doesn't engage

Navigator: You were right on the money! Thanks to OB and Schematic also. I tested the voltage at the starter and it read 12 volts. Cranking was 8.5. Other engine was 12 volts with both.<br />I then used a jumper to connect the + of the battery right to the soleniod. Same thing. Jumped the - and guess what? Started first try!<br />Replaced the ground cable from engine to battery, cleaned all contacts and it's great.<br />Once again, thanks to all.

 

[Navigator]

Re: Spinning starter, but doesn't engage

Glad to help <br /><br />Nav