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  Mercury 90-HP: Starter Motor Problem

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Author Topic:   Mercury 90-HP: Starter Motor Problem
JBG777 posted 10-17-2008 06:48 AM ET (US)   Profile for JBG777   Send Email to JBG777  
I was recently out fishing, starting and stopping [a 2004 Mercury 90-HP two-cycle outboard motor], chasing bunker pods around. Sure enough, I went to turn the key after shut off and the [starter motor] was spinning but not engaging. I eventually got it started by wedging a screw driver and prying (putting pressure) on the [drive gear pinion]. I got back to my slip, turned the key ten times, and no [problems]. Starting the eleventh time, same [starter motor problem]. I got it started by [using the same screwdriver pry procedure]. I recently bought a new starter, and, after reading some of the threads, I'm not sure if [the new starter] is the problem. I'm going to replace [the starter] today but if I can send the starter back, I would save about $275. Let me know your thoughts, and thanks in advance.

Joe

jimh posted 10-17-2008 09:04 AM ET (US)     Profile for jimh  Send Email to jimh     
Because the malfunction only occurs about ten-percent of the time, perhaps there is a problem in the alignment between the starter motor shaft and pinion gear and the flywheel.

If the new starter motor is defective, I would ask that it be replaced for free.

ASIDE: The term "Bendix" is often used to describe the drive gear pinion on an electric motor used for starting a larger internal combustion motor. The Bendix mechanism consists of a helically-grooved drive shaft which sends the pinion gear outward on its drive shaft to engage the flywheel. According to an article in Wikipedia, the Bendix drive mechanism may no longer be used in many starter motors, having been replaced by a one-way spring operated clutch called a Sprag clutch.

Cf. http://en.wikipedia.org/wiki/Automobile_self_starter

jimh posted 10-17-2008 09:07 AM ET (US)     Profile for jimh  Send Email to jimh     
In another recent discussion there were anecdotal reports of seven starter motor failures on relatively new Mercury outboard motors:

Cf.: http://continuouswave.com/ubb/Forum8/HTML/003378.html

I don't know if the same starter motor is used on your model of Mercury outboard. You might check with your dealer to see if there is an up-graded replacement part available.

JBG777 posted 10-17-2008 04:39 PM ET (US)     Profile for JBG777  Send Email to JBG777     
Jim,

I replaced the bendix ealier in the summer along with the fly wheel. It was locking up as you indicated and I believe that issue was directly related to a weak battery. However, from it always locking up it did chip some teeth on both the wheel and the bendix. After replacing the starter it seems to be working but I'm always cautious that it could be electrical. Thanks for the help and will let you know the outcome.

jimh posted 10-17-2008 08:56 PM ET (US)     Profile for jimh  Send Email to jimh     
If I understand your narrative correctly, on your 2004 Mercury outboard motor you have replaced the flywheel once and replaced the starter motor twice. I think that is very unusual. Generally a flywheel and starter motor are considered to be lifetime components on an outboard motor in recreational use. You just don't hear of them being replaced, especially not on a motor from 2004.

It seems to me to very unusual to have to perform so much service on the starter motor of your Mercury outboard, and especially all out of warranty.

JBG777 posted 10-18-2008 05:15 AM ET (US)     Profile for JBG777  Send Email to JBG777     
I only replaced starter motor once(yesterday). However, did replace the pendix on my initial starter. The flywheel wasn't a cheap date.
jimh posted 10-18-2008 09:03 AM ET (US)     Profile for jimh  Send Email to jimh     
If I understand your narrative, you are about to install the third starter motor on your Mercury 90-HP two-cycle outboard. In addition, you have also replaced some component of the starter motor which you variously call the "pendix" or the "bendix" but I believe to actually be some portion of the starter motor assembly which is related to the spring-loaded one-way clutch for the pinion drive gear. And you have also replaced the flywheel once.

Again, this seems like an enormous amount of repair and replacement on the electric starting system. An all of this was done without any support from Mercury under the terms of their warranty? Do you operate your boat in a manner which requires the engine to be started over and over?

domlynch posted 04-04-2011 04:17 AM ET (US)     Profile for domlynch    
Hi,

I have the same/similar issue on a 2008 Optimax 90 (with only 39 hrs + 2 new brand new batteries), the starter motor only sometimes has its pinion jump up to engage the flywheel, but it doesn't kick the motor, & sometimes the starter pinion doesnt even rise to engage the flywheel. Hence I cannot get the motor to turn over with the starter motor. I did remove the plugs & put a small amount of oil in the cyslinders and hand turn the motor over, that was easy i.e. the notor is not seized.

Hopefully a minor issue,(could be stuck brushes), will try to get it fixed under warranty. The motor is virtually new being a repower on a 1988 Montauk.

Personally I prefer Japanese motors (never had any issues with them & their wiring/castings etc. to me seem so clean/precise/refined) over Merc (and some others) etc but I shouldn't complain as the boat is a hand me down !

I am confident the Opti will be fine once this is remedied....

aah...just another thing to get fixed on an old boat ! (can't use it without startin'....)

Cheers,

Dom

domlynch posted 04-04-2011 04:19 AM ET (US)     Profile for domlynch    
Hi,

I have the same/similar issue on a 2008 Optimax 90 (with only 39 hrs + 2 new brand new batteries), the starter motor only sometimes has its pinion jump up to engage the flywheel, but it doesn't kick the motor, & sometimes the starter pinion doesnt even rise to engage the flywheel. Hence I cannot get the motor to turn over with the starter motor. I did remove the plugs & put a small amount of oil in the cyslinders and hand turn the motor over, that was easy i.e. the notor is not seized.

Hopefully a minor issue,(could be stuck brushes), will try to get it fixed under warranty. The motor is virtually new being a repower on a 1988 Montauk.

Personally I prefer Japanese motors (never had any issues with them & their wiring/castings etc. to me seem so clean/precise/refined) over Merc (and some others) etc but I shouldn't complain as the boat is a hand me down !

I am confident the Opti will be fine once this is remedied....

aah...just another thing to get fixed on an old boat ! (can't use it without startin'....)

Cheers,

Dom

domlynch posted 04-04-2011 04:20 AM ET (US)     Profile for domlynch    
Oops ...sorry... I didn't mean to post this twice
domlynch posted 04-10-2011 02:21 AM ET (US)     Profile for domlynch    
Took it to a Merc Authrosied Service Centre to get it fixed under warranty....will pick up boat next weekend.

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