Yamaha F350 (2009) shift shaft seized in lower unit

[B1tuna72]

Shift shaft in the lower unit (counter rotating motor) will not move. Lower unit has been removed from the motor and reasonable force has been applied directly to the shift shaft...no movement. Boat was last used in Nov 2018...boat is kept on a trailer, and everything worked perfectly when last used. There has been no damage to prop or skeg while stored. Ideas?

[walleye1]

The shift shaft has to be turned in the proper direction before pulling it, do you have a manal?

[99yam40]

have you checked for water in the lower unit lube?
did you try turning the prop while trying to shift to make sure the clutch dogs lined up properly?

If that is not the problem, then rust/corrosion is the only thing I can think of that would cause this

[B1tuna72]

Clarification - at this time I am not trying to remove the shift shaft from the lower unit. The shaft is seized and cannot be moved in any direction...it will not turn. The lower unit is in neutral, so the prop turns freely as it should. When the lower unit was drained, the gear lube was milky, so water intrusion had occurred. However, what drained out was not all water, maybe a 50/50 mix. There is no rust or corrosion evident on the outside of the lower unit.

[99yam40]

I would be worried about the internal parts that have to move being rusted not the outside of the casing.

It is always a good idea to change lube at the end of a season before setting up for months, just to make sure there is no water intrusion so the unit does not sit like that for a long time.

I would think that opening up the lower unit would be the next step

[99yam40]

I did not get a response from you on if the prop shaft or the drive shaft where being turned when trying to shift?

[B1tuna72]

Turning the prop shaft or drive shaft, while simultaneously trying to turn the shift shaft, does not change anything...the shift shaft cannot be turned.

[walleye1]

Sound's like the clutch is glued to the prop shaft. Pull the carrier set the drive up and fill it with pen oil let it soak.

[walleye1]

If the the clutch is stuck you should do a complete rebuild.

[boscoe99]

Is the propeller shaft still installed?

[walleye1]

He can't turn the shift shaft so I guess it is in the case still.

[B1tuna72]

Walleye: I agree with the complete rebuild, but trying to get an idea of whether the case will need to be replaced. I have a complete lower unit located at a reasonable cost and it might simplify things to go.

Boscoe: Yes, the prop shaft and prop are both installed.

[walleye1]

A new complete gear case new is 7k, yours more than likely can be rebuilt.

[B1tuna72]

Yes, I know, that's why I started looking for a used one in working condition

[walleye1]

You don't know what you are getting though.