help!!!! shifting woes 72 125 johnson

oharek

Recruit
Joined
Feb 18, 2005
Messages
5
I took my boat out for the first time, started and ran great, however when i went to shift to reverse the engine just reveed and sounded like it was trying to shift and the gears were not hooking up right. This happens in both forward and reverse. The prop is spinning but the boat isn't going any where and it sounds like it keeps trying to shift. The previouse owner said he never had any problems and the boat worked great all last year, he had a new power pack and everything put in. Please help!!!!!
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: help!!!! shifting woes 72 125 johnson

The following will explain the shifting setup on your engine. Possibly you simply have the wrong gear lube in the lower unit.<br /><br />(Hydro Electric Shift)<br />(J. Reeves)<br /><br />The shifting setup of the lower unit is what's called a "Hydro Electric Shift", which is quite complex consisting of voltage being applied to solenoids in the lower unit which in turn change oil passages via a oil pump that supplies various pressure on a spring loaded shifter dog. The wires leading to the lower unit (at the powerhead) are "Green" and "Blue". The engine must be running or cranking over in order to shift out of forward gear.<br /> <br />You CAN NOT use HI VIS lube in that lower unit. You MUST USE what OMC calls "Preminum Blend" lube, commonly called "Type C". (A thinner lube) <br /><br />In neutral, you need 12v to the "Green" wire. <br />In reverse, you need 12v to both wires, the "Green" one and the "Blue" one. <br />In forward, there should be no voltage to either wire. (The spring loaded shifter dog forces the unit into forward gear) <br /><br />To check the lower unit for proper shifting to make sure you have no trouble there, remove the spark plugs to avoid problems and to allow a higher cranking speed. <br /><br />This next step eliminates the actual shift switch in case problems may exist there.... Disconnect the blue & green wires at the knife connectors (the rubber insulated boots) leading to the lower unit at the powerhead, then using jumpers, take voltage direct from the starter solenoid to apply voltage to the "Green" wire for neutral, then both wires 'Green" & "Blue" for reverse (Remember the engine must be cranking over in order to shift).<br /> <br />With no voltage applied, the unit should be in forward. No need for a ground jumper... the lower unit's already grounded. You may crank the engine with the key switch or by energizing the starter solenoid with a jumper wire.
 

oharek

Recruit
Joined
Feb 18, 2005
Messages
5
Re: help!!!! shifting woes 72 125 johnson

I haven't checked the lower unit lube yet, is it posible fot the wrong oil to cause a prb like this, or could something have happend from sitting all winter? thanks for he quick response
 
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