1971 50hp 50173S Outboard (won't shift to neutral/reverse)

[Brian A]

Hello all! This is my first post as I just recently purchased my first boat (a used one). This boat came with an older Evinrude 50hp (model 50173S).

I put it in the river yesterday for the first time, and the motor started right up, but seems that it is stuck in forward. Pressing the neutral or reverse buttons on the Evinrude Selectric has no effect. It would run nice and slow when at the "start" indicator on the throttle, enough that the boat wasn't getting any forward momentum, so it wasn't too bad getting off the dock and running about. I tried to slow the motor down as much as I could incase rpm was an issue why it wouldn't shift to neutral/reverse, and still no joy.

Other than the shifting issue the motor seemed to run quite well. When I got home I decided to change the gear oil (not sure why that didn't occur to me prior to going out). Not much gear oil came out of the lower end, but I was able to put a lot of new oil back in (until it came out the fill plug). I certainly put in a lot more than what came out.

I also took the Selectric off the side of the boat and checked to see if the wiring was connected to the buttons (which it is), and popped the top off the motor to see if the wires were connected on that end, and they seem to be. I'm fairly handy with mechanical things once I know what's going on (as I work on my motorcycles 2 strokes and v4s without any issues), but I've never worked on an outboard motor.

I'm not sure if changing the gear oil (with the great increase of oil being present now) is going to solve my shifting issue, or not? If not, can anyone point me in the right direction or something to test?

Thanks very much in advance for any response!

- Brian

 

[rayodunne]

Re: 1971 50hp 50173S Outboard (won't shift to neutral/reverse)

Copy Paste from J Reeves:

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

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.


Large slotted screw at lower portion of lower unit is the gearcase drain screw. A identical screw further up the gearcase is the oil level screw. Fill from the bottom drain hole until the lube flows out the top oil level hole.