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Motor won't go into forward gear.

Idahoboatguy

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I have a 1970 evinrude 115 motor that won't go into forward gear. I took it out a week ago and it ran great. Then the next day went out with it and it wouldn't shift into forward gear. So I drained the lower unit and filled it back up with new oil, type c and it still won't shift into forward gear. Any help I'd appreciate.
 
Forward gear is the default on a hydro electric shift. With the battery disconnected does the prop spin free? If not you need to take the gearbox apart and see whats going on inside.
 
I have a 1970 evinrude 115 motor that won't go into forward gear. I took it out a week ago and it ran great. Then the next day went out with it and it wouldn't shift into forward gear. So I drained the lower unit and filled it back up with new oil, type c and it still won't shift into forward gear. Any help I'd appreciate.

Engine Model Number?
 
So if I disconnect the battery cables with the motor off it should lock into the forward gear? Because the motor now is in neutral. Also do I have to do anything else after disconnecting battery cables? Thanks for all your help, I'm new to all this.
 
Disconnecting the battery while the engine is running will damage the charging system... DON'T DO THAT!

If the propeller locks into forward gear when the engine is NOT RUNNING, but will not go into forward gear when the engine is running... you have the wrong shift switch wired in OR have voltage going to the lower unit somehow.

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(Hydro Electric Shift System Explained)
(J. Reeves)

NOTE 1 -The ohm reading of the individual shift solenoids should be between 5 to 6 ohms. The ohm meter should be set to low ohms. The shift wires leading to the solenoids must be disconnected when being tested.

NOTE 2 - The solenoid plunger measurement must be made with the solenoid placed within the lower unit. The measurement must be approximately 1/64" beneath the top surface of the solenoid... NOT above the solenoid surface nor any lower than 1/64" of the solenoid surface. This factory measurement is critical and will not ever change UNLESS someone has tinkered with it.


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.

You CAN NOT use HI VIS lube in that lower unit. You MUST USE what OMC calls "Premium Blend" lube, commonly called "Type C". (A thinner lube)

Note: The engine must be running OR have the driveshaft turning by some other means in order for the engine to shift.


In neutral, you need 12v to the "Green" wire.
In reverse, you need 12v to both wires, the "Green" one and the "Blue" one.
In forward, there should be no voltage to either wire. (The spring loaded shifter dog forces the unit into forward gear)


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.


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).

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.

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http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
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It sounds like it is sticking inside the gearbox, by disconnecting the battery if it dont go into fwd gear it is internal in the gearbox.
 
The propeller spins freely with the motor off and the motor on in neutral. I checked the switch at the blue and green wires with key on and motor off and it all checks out good.
 
It isn't so complicated to figure out. It has to have the proper electrical input AND be running to shift out of forward gear. if prop spins freely (neutral) with the motor not running, the shifter piston is stuck in the oil pump bore. Complete lower unit disassembly is required to fix it. You will need a good service manual if you have never done one.

BTW, very fine grit in the oil is what causes the piston to stick. That's why oil changes are mandatory.
 
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