newbie here(SOLVED)

[saultguy]

Have a 16' trihull bowrider with 120hp omc I/O. I searched the engine model number and found it to be a 1973 engine. Runs fine, accelerates fine, the only issue I'm having is when easing up on the throttle it will sometimes come out of gear rev up, then "clunk" back into gear. Usually only happens when im near the lowest forward area of the shifter? Any Ideas?

 

[kenny nunez]

You may have a bad shift switch which is in the control box. The wires that go through the transom need to be checked. Also try changing the oil in the lower gear housing and make sure the oil says FOR ELECTRIC SHIFT. If you do not stop the drive from doing what you are describing you will end up either shearing a shaft off or breaking the forward clutch spring. The 2 wires are colored coded green for forward and blue for reverse. There are rubber sleeves covering the connections at the transom. Use a test light on each one while someone moves the handle, the ohm reading on each wire to ground going into the drive is 4.6- 5.4 on low scale.

 

[saultguy]

thanks Kenny, how would i check the shift switch, it seems weird to me(newbie) that it always happens at the same spot(give or take) on the shifter, and really only when slowing from full throttle

 

[saultguy]

I took the prop off, because i had purchased a new one, and I noticed while removing it, that there is(was) no thrust washer installed, its a smooth shaft pin drive prop?

 

[kenny nunez]

There should be a brass washer between the drive pin and the prop hub. Follow the wires out of the control box and there will be a plastic fitting that the wires are plugged into. Check the wires for 12 volts going into the box should be purple, the 2 white ones or yellow with a red stripe are for neutral interlock and the green & blue are the wires to the drive. Put the shift in forward with the ignition on and test the green wire. It could be a worn control box that the shift switch becomes disengaged from the throttle control.

 

[saultguy]

So I think the problem is solved, when I got the boat(about a week ago), the original prop was in pretty bad shape so I ordered one from a prop website, look very very similar, but the back on the prop where the hub enters was slightly different, went on nicely and everything fit, so I didn't give it another thought. On a whim I put the original prop back on and no issues anymore. Now on to find the right prop.