Mercury 50hp - Alternator and Bendix gear

[Hooksetter]

First, let me say I have always found these forums helpful. Now I am posting a question of my own.

I am no mechanic, but trying to learn the most I can. I have searched around on the site, but can't find what I am looking for.

OK - 50hp Merc. A couple outings ago I started having a problem when starting the motor. The engine would sound extremely weak like it was barely turning over. I went to battery and tightened everything and then it fired right up. The rest of the day it would fire up just fine, but randomly would do the same thing and sound like it was dead. I started thinking I had a bad battery and since it was old I went ahead and replaced it. Yesterday I was out and the engine again sounded extremely weak when trying to start and then would suddenly fire up.

At home I put engine in a water tank and took cover off. I noticed after trying to crank that the bendix gear remained stuck in the up position. We had to tap on it with a small hammer to get it to release. Sprayed WD-40 on the gear and that seemed to really help out. Of course I have not been able to replicate the weak starting sound at home. After lubricating the Bendix seems to not be sticking anymore.

Is it possible that on recent outings the bendix has been stuck in the up position when I have been motoring? I have never heard any noise to indicate this. This doesn't seem like it would be good for the starter at all.

My other problem is the alternator, I noticed yesterday that after fishing the cranking battery was showing a low voltage. The alternator doesn't seem to be charging it during the day. I put a volt meter on battery while engine was running and it was only showing 12.6 volts. I remember in the past that when idling my Lowrance unit indicated voltages anywhere between 13.5-14.2

So now at this point:
1. what kind of lube should I put on bendix gear?
2. is it possible the bendix was ever stuck in the up position while motoring?
3. Is the random weak starting noise related to the bendix possibly being stuck?
4. What are additional things I can do to check alternator issue?

sorry for such a long post and if you read it all I really appreciate it

 

[Hooksetter]

Re: Mercury 50hp - Alternator and Bendix gear

follow up:

I just went out and started again and noticed the bendix did engage immediately, but it still didn't make the really weak sounding noise. Tough to tell difference in noise compared to when the cover was on.

Also, I disconnected positive cable while engine was running and it didn't die so alternator has to be doing something. I'm still unsure why it shows a lower voltage at battery while engine is running and why new battery was drained after limited use yesterday.

 

[Barnacle_Bill]

Re: Mercury 50hp - Alternator and Bendix gear

Makes sure all connections are clean and tight. Did you charge the new battery before installing? A light lube is all that is needed for the starter bendix. You most likely have a blown rectifier and that is why your battery isn't getting charged. If it wasn't blown before it is now since you disconnected the battery with the motor running.

 

[Hooksetter]

Re: Mercury 50hp - Alternator and Bendix gear

I had read the best way to check alternator was to disconnect cable. I don't know much about rectifiers, but I read a symptom of them not working is your tach gauge doesn't work. I don't remember the last time my tach gauge worked.

 

[Barnacle_Bill]

Re: Mercury 50hp - Alternator and Bendix gear

Outboards do not have an alternator like on your car. They use windings on the stator for creating AC voltage which is in turn sent to a rectifier to be converted into DC voltage.

 

[Hooksetter]

Re: Mercury 50hp - Alternator and Bendix gear

does the weak starting noise sound like it might have been an issue with the bendix gear?

 

[Barnacle_Bill]

Re: Mercury 50hp - Alternator and Bendix gear

No thats usually caused by a bad connection or weak battery.