1997 merecury force 120 shift shaft spins freely

[brendanmcd37]

hey guys, brand new to the forums. i recently just inherited a 1987 suntracker bass buggy pontoon through a recent family member passing, it has a 1997 mercury force 120 2 stroke on the back.i got it running and took it out on its first maiden voyage earlier this week, and found as soon as you start the engine, its in forward gear and driving, no neutral or reverse. when you put it into reverse, it drives forward faster.i know absolutly zero history on this boat/motor and have no prior knowledge as to whats been done it it before. after doing some reading on the forums it sounded like this was a fairly common problem and that all i would have to do is take the lower leg off, and put some pliers on the shift shaft and spin it to forward detent, and then install the leg with controls in forward gear. after taking the lower leg off last night, the shift shaft spins freely, with zero resistance, doesnt matter what direction i turn it, it just spins and spins. so i popped the bushing/keeper that holds the shift shaft down off, and pulled the shift shaft out to see what i can see down there and im not to totally sure what i should be looking at down there, but what i beleive to be is the cam doesnt feel like it has any splines left in it. with a very long screw driver feeling the edges in the cam where the splines should be, i can feel slight bumps and roughness but no splines. splines on the shift shaft look completly fine. the bolts holding the leg on had antisieze on them and werent all that tight, and by looks of the impeller it is new-ish, im assuming when it was put back together last whenever the impeller was done, it wasnt assembled properly and its ran this way for some time now. what should my plan of attach be for getting this old girl back together properly here? im new to fixing boats, but i have a mechanics background and am not scared to tackle anything, just looking for some advice on where to go from here now. thanks guys, hope this wasnt to long and drawn out

 

[The Force power]

:welcome:
You'll have to pull the prop-shaft/bearing-carrier etc. out & properly install the cam/shaft.
Get a seal-kit for the lower-unit & Impeller, now that you're taking it apart

 

[brendanmcd37]

:welcome:
You'll have to pull the prop-shaft/bearing-carrier etc. out & properly install the cam/shaft.
Get a seal-kit for the lower-unit & Impeller, now that you're taking it apart

kinda what i was figuring. ill try and get a seal kit from the dealer and find a manual and tear this down then

 

[The Force power]

kinda what i was figuring. ill try and get a seal kit from the dealer and find a manual and tear this down then

You can get all these parts in the IBoat store right here
A lot of information needed to do this has been explained & discussed multiple times, type in key words in the search-bar under advice and you'll find lots of info.

Keep us posted :ranger:

 

[jerryjerry05]

Look up the parts diagram for the lower unit.
The shift rod is threaded through a cam that operates the dog allowing it to shift gears.
IF?? the rods been pulled out(probably) the cam drops down into the housing and the unit sticks
in forward gear.
If the cam moves??? it can destroy the F gear.
You'll need to disassemble the lower unit to install the cam.

When you pull the propshaft, the end can fall out and 3 ball bearings will drop out and disappear.

 

[brendanmcd37]

thanks for the responses guys, i was about to start tear down and found a deal on a guy that has a 1996 120 force with a blown engine but says the rest is good and leg is in great shape. if i can get this whole motor for cheap enough, will the leg from the 96 be the same? what should a guy be looking at to make sure? figured it would be easier if a guy can score the whole parts engine for a reasonable price to go that route