Reverse/Neutral Outboard Problems on Mercury 125

[jwilson_46143]

I have a '97 Mercury 125 on my boat. I was cruising about 25mph yesterday and unexpectedly came up on some VERY shallow water. I immediately (and stupidly) threw the remote in reverse to slow the boat, and the motor made an awful grinding noise for several seconds before I put it back in neutral. The rest of the afternoon the motor wouldn't properly drop into reverse (made clickly noises and hesitated) and made a clicking noise in neutral. Finally, at the end of the day, the motor wouldn't drop into reverse at all (no noise present). Shifting into forward is normal, and the motor runs normally at speed going forward. I'm new to boating and don't have a clue where to begin with troubleshooting. I'd like anyone's opinions/knowledge before I open up my wallet at a service shop. Thanks in advance for your help!<br />Joe

 

[gw204]

Re: Reverse/Neutral Outboard Problems on Mercury 125

Joe,<br /><br />Drain you lower unit oil and look for any signs of metal shavings. You may have fried the reverse gear. That's all I can think of. Don't know much about lower units.<br /><br />Good luck.<br /><br />Brian

 

[jwilson_46143]

Re: Reverse/Neutral Outboard Problems on Mercury 125

More info on this problem....I tinkered with the motor and shift linkage last night. <br /> <br />First the gear shift linkage: observed that when shifting into forward and neutral the shift linkage inside the motor cowling "clicked" into gear. No such "clicking" into gear of the motor shift linkage was present when shifting into reverse. Also, shifter itself doesn't feel normal going into reverse----it just doesn't feel like it's engaging. I attempted to adjust the linkage to slightly favor reverse but didn't have the time/tools I needed. <br /><br />Also observed the following: when shifted into forward, prop turns forward with clicking noises and locks backward. In neutral, prop turns both directions with clicking noises (normal??). In reverse, prop locks forward but will not turn backward. Is this due to not being properly shifted into reverse, or something more heinous like a destroyed reverse gear?? <br /><br />Proceeded to drain gear case oil to look for metal shavings/chunks. There were some VERY fine metal shavings on the drain plug. I couldn't feel or see any shavings or chunks in the drained gear oil. I want to believe I'm having shifting/linkage problems. Your input is greatly appreciated. <br /><br />Joe

 

[aeronutt29]

Re: Reverse/Neutral Outboard Problems on Mercury 125

First, a disclaimer: I'm throwing this out from experience on my '69 100 HP Merc, so it's possible that yours is different.<br /><br />It's normal for the prop to ratchet forward and lock the other way when the shifter is in forward mode. This is because the forward gear engagement uses a spring loaded pin against a "sawblade" shaped pawl. <br /><br />When the shifter is in neutral, the prop spins freely in either direction with no clicking noises at all. <br /><br />The reverse gear does not use the ratcheting sawblade type of engagement and instead has opposing rings of square pegs that move closer together and lock into each other. This means that the prop will not turn forward or backward unless you turn hard enough to make the powerhead turn too.<br /><br />Now, since you had a significant amount of forward momentum that was trying to keep the prop spinning one direction and tried to apply lots of horsepower in the opposite direction, the only place for all that power to go was against those opposing rings of square teeth. I would guess that the tips of those teeth got rounded out a little bit and the filings from that high-pressure contact is what you found in the oil. You may also have bent the shift shaft so that the cables need to be adjusted a few turns to compensate. On my motor, this is fairly easy to do by releasing a little lock lever (push in, 1/4 turn left, pull out 1 inch), spinning the mount block on the cable casing, and re-installing the mount block with the lock lever. If the shift shaft is bent to where it ALMOST engages forward gear when the shifter is in neutral, this would explain the clicking that you hear when you turn the prop. It would also explain why you can't move the lever far enough back to get reverse to engage.<br /><br />If adjusting the linkages doesn't get it back to the way it worked before, you might just have to bite the bullet and pay your local marine service shop a few Jacksons. There are very few backyard mechanics (myself included) who have the tools required to work on a lower unit. I'm as happy as can be to pull the powerhead apart and put new rings in, but I pay the local marine shop to do any work inside the lower unit.