Mercury 115 not shifting into reverse

mike kobel · #1 January 3rd, 2003, 08:42 AM

My '70 Mercury 115 is a 6 cylinder, 2 stroke electric start. This motor is pushing a 17' 1970 Glastron shallow V bottom. Shifts into forward just fine, but grinds and makes a lot of noise when you shift into reverse. Had it on the Ohio River in November, rpm only 3800 two times, then dropped to 3200 rpms. Hoping that my problem is all in my linkage. Fuel mixture is 50:1, plugs are Champions L76V, prop is a two blade [not sure of pitch]. This is my first boat so I am not real boat smart. Learning fast.

Waterbugtoo · #2 January 3rd, 2003, 09:10 AM

Either your cable is out of adjustment, or the clutch dog and gear is badly worn. It may be all of the above. With boat on trailer, back it down the ramp. Unhook shift cable and manually shift into reverse. What does it do? If it goes in gear completely and cleanly, then the dog and gear may be ok, and a cable adjustment or replacement may take care of the problem. If it still makes the noises or jumps out of gear, then the dog and gear will probably have to be replaced as well as cable.

KennyKenCan · #3 January 3rd, 2003, 11:08 AM

Are you sure about a 2 bladed prop. If that is what you have, I would suggest that you change to a 3 bladed model like 13 1/4" X 17". It will provide alot less slip and alot more performance. This will not fix your shift problem though. I would follow Waterbugtoo's suggestion for that.

rons boat · #4 January 3rd, 2003, 03:42 PM

Some of those good ole two blades do a fine job. Still you have to use the tach to make sure. He's IMHO got you on the right track by disconnecting the shift control at the motor and isolating the problem.

TORX · #5 January 3rd, 2003, 10:59 PM

allso check shift cam it will were and will not push the dog all the way in or the shifter shaft may be twisted

XTREMEBASSBUSTIN · #6 July 17th, 2008, 02:56 AM

WHAT IS HAPPENING- I can shift in forward and boat is propelled forward but going from neutral to reverse the boat goes nowhere. All that I hear is a loud clicking and grinding noise from the engine upper cowling. I frequently flush the motor after every tournament I fish and run through the gears. While flushing the motor I shift in forward I get the loud clack and the prop moves (forward directional spin) but when I go to reverse I DO NOT HEAR THE LOUD CLACK but the prop does move in reverse (opposite direction from the forward spin) but once the boat is in the water is when I get the grinding noise and nothing happens while shifting into reverse.

I have a general idea of what it might be but would rather have advise from the experts on this issue before I start throwing parts at it in hopes of fixing my problem.