Mercury 402 Starter question

munster04

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Sep 26, 2015
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35
Hello all,

I've been reading your site for the last three weeks since I purchased my fishing boat. Have to say this forum is full of very helpful information on motors plus other things like how to preform a drop volt test.

I'm hoping someone might help me with my starter issues. First let me explain everything I have done so far and why I started down this path.

The first weekend I purchased the boat the motor ran one time then would not start. (Bad starter see below.) This is where all the reading and test started when I got back home from my trip up north. When from a fishing trip to a trip in three hours. :)

Motor is a 40 HP Mercury S/N 5042861.

First things I check with the help of this link.
http://www.iboats.com/basics/diagnose_starting_problems.html

Battery - Replaced with new one. (800 CCA)
Wire harness - Turned out REALLY bad Replaced it. (Harness to controls and battery. Main harness inside the motor was less them two years old the guy said.)
Starter - Dead - Replaced it. (Dead in motor and straight connection to known good battery after I pulled it.)
Solenoid - Good but replaced with new one that mounts to block instead of starter.

Took all wires off one at a time and cleaned until shiny and cleaned inside of connector as well.
Replaced wires that had been broken of low volt test. (Downloaded wire diagram from this site.)

All test done based on what I have read on this forum.

Now my issue:
After I put the new starter in the motor along with the new solenoid the starter motor engage the flywheel two times. Now the Bendix just spins. I pulled the starter again to make sure all connections where tight. I cleaned the ground block connection spot as well and all ends again. Reassemble everything but the same issue.

Testing part:
Charged battery over night to ensure it was fully charge.
Tested volts drop - found nothing.
Checked all connections again. Wiggle test

Connected the starter to the battery directly again and it still would not raise all the way up.
​Grabbed the battery out of my vette just to rule out the battery but same thing, Bendix just spins.
Lubed the shaft that is on top of the starter only. Used lithium grease.
I've never taken a starter apart so not sure the process. This starter is only one week old as of two day.

I know the polarity is not reversed on the batteries. When I purchased the battery I color coded the terminals because friends would be using the boat.
I have not loaded tested the battery but it was dated 9/15. The other battery is less than six months old and I always have it on a trickle charger.

I used heavy wire jumper cables for the direct connect testing. (Unhooked all other wires from the stater to solenoid.) I tried both direct ground connection on battery to motor block along with direct ground to starter for the test. This was the last test I did with the starter. It's now sitting beside me on the end table incase someone tells me I have to pull it apart.


Thank you for any help offered. Willing to try anything at this point in time.
 

Fed

Commander
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Apr 1, 2010
Messages
2,457
Lubricate the bendix spiral, you will have to turn it clockwise and lift at the same time by hand.
 

munster04

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Sep 26, 2015
Messages
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Thank you for your reply. Is there a trick to get it to lift as you twist it? I put in the vise and tried to get it to spin and lift but no luck yet.
 

Fed

Commander
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Messages
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There's no trick it should just turn (clockwise) and lift with your fingers.
Needless to say don't try this with the key in the start position.
 

munster04

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Sep 26, 2015
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35
No worries about it starting, I have it in my shop in the basement currently. It really is stuck them because I can't get it to do anything but spin. Even when I turn it upside down in the vise and try to push it down as I turn it. I'll keep working on it and let you know if I can get it to move up.
 

Fed

Commander
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Messages
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I wouldn't use too much force on it, there seems to be something wrong here.

It worked twice & now you can't get it to move by hand???

Something is not adding up, it should turn & lift easily. Got a picture of it?
 

munster04

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Fed,

Well I have to say you made me think this morning when you asked for the picture. I went out to the box of parts I putted off the boat to look at the old starter. You are correct that the bendix spins with just my hand. I then put them side by side and now feel like an aXX! They both are the same as far as size and motor mount. However the old Bosch starter has a spring under the bendix. The new aftermarket version as a small spring on the shaft above the bendix. The aftermarket one has a nut under the bendix.

I just went back and looked at the order slip and the part number is correct according this the parts catalog. Part number 50-55601 or aftermarket 18-5601. Not sure what happened but from the looks you can see they are different. (Amazon order.. Ugh)

Still a little confused how it cranked two time before if this one is the wrong one. I remember it trying to turn over because my neighbor say will goes my dog when it was trying to turn over. I stopped before as soon as it started trying because I did not have the spark plugs on. I did not have the water on or the motor in the trash can,

Here is the picture showing the two of them side by side.

Looks like I'll be ordering another one that matches the old Bosch starter or trying to rebuild the old one. I was going to rebuild it and save it anyways.
 

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munster04

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Fed,

I just looked at the one on this site as well. It's just like the aftermarket one I have in the picture. See the link below.
http://www.iboats.com/Premium-Outbo...3805987--**********.440689653--view_id.174811

Now I'm back to thinking the bendix might be stuck. I have not found any videos or manuals online showing how to taking apart a starter in detail. Most are limited to "Do this" then "Do this" and reassemble.

It looks like this one has an o-ring at the top retaining the upper collar and spring. I'll pull the top off the see if I can get the shaft out without damaging anything. Not sure if the nut on the bottom of the bendix is held on by a flange or ????

​If you have any ideas let me know what I should try.

Thank you,

Munster04
 

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munster04

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Update.. I got the bendix to spin up after giving it pressure with a screw driver. I took off the bendix because I could feel it catching every time it fell back to the bottom. When I removed the bendix I could see a grove at the start of the treat that is catching as it fell back down. (only part that was shiny silver not shiny gold.) I'll try and smooth that out testing after each pass of the emory cloth.

I'll keep you posted.
 

munster04

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Sep 26, 2015
Messages
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It works now Fed.

I did the old QTip test to find the bur.

I direct connected it to the battery and it works great. I'll reinstall and keep working on the motor.

Thank you for your replies.

Munster04
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
That must have been some bur, are you now using the new starter?
Lube the moving surfaces of the bendix, I use a waterproof light lithium spray grease which has become my best friend recently.
 

munster04

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Joined
Sep 26, 2015
Messages
35
It was a bad cut on the threads. They did not finish one of the cuts correctly. After I installed it back in the motor it started right up. I did use a little lithium after I removed the bur. If it happens again at leased now I have a better understand of how the starter motor works. This is the first motor I've worked on.

Thanks again for your time.


Munster04
 
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