Change Lower Oil on Selectric Now Won't Shift

[71erude]

I changed my lower unit oil on my 71 50hp selectric shift. I used the required "Premium Blend" OMC lower unit oil (type C) -- I filled from the bottom fill hole until it came out the top hole. Now it won't shift out fof orward. Check resistance on leads to solenoids and had 8-9 on both.

Any ideas?

 

[tashasdaddy]

Re: Change Lower Oil on Selectric Now Won't Shift

Hydro Electric Shift)
(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)

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.

 

[Nippissinger]

Re: Change Lower Oil on Selectric Now Won't Shift

And that's why we call him "Cheif"....

Thanx for all your help TD..

Will

 

[71erude]

Re: Change Lower Oil on Selectric Now Won't Shift

the prop spins counter clockwise no matter what gear I place it in. Wouldn't counterclockwise spinning indicate that it's stuck in reverse?

It was shifting fine before the gear oil change;

 

[F_R]

Re: Change Lower Oil on Selectric Now Won't Shift

the prop spins counter clockwise no matter what gear I place it in. Wouldn't counterclockwise spinning indicate that it's stuck in reverse?

It was shifting fine before the gear oil change;

Maybe it had something to do with the oil change, but probably not. Whenever checking out the system you should always start with electrical checks. You tested the solenoids and they are OK. Now check the voltages as Reeves said. Electircal problems are WAY more common than lower unit problems. Especially the shift switch.

A real quick check would be to simply disconnect the shift wires at the powerhead and start it up. It should be in forward gear. If it truly is in reverse with the wires disconnected, you do have a problem in the lower unit. Stuck piston in the oil pump. That's assuming you haven't been messing with the solenoids.

 

[71erude]

Re: Change Lower Oil on Selectric Now Won't Shift

Thanks for all this good advice about my Selectric. From all my test it seems that the lower unit solenoids are getting the correct voltages from the switch. I went out and tapped the side of the lower unit with a rubber mallet and it switched into forward gear - I think the switch may have been powered on the reverse button pressed when I drained the lower unit. Would that have affected anything? Is the hydraulic pump not getting primed or something?

 

[tex599]

Re: Change Lower Oil on Selectric Now Won't Shift

SHould not have effected anything by changing oil with switch in reverse. Should always default to forward in the case of failure. Pretty simple system and works great as long as water is kept out of lower unit we have a 72 50hp Evinrude, that we have owned since new.