Lower Unit/Shift Shaft Installation Issue???

[bighermHK45]

Ok, I went to install the lower unit on the 1999 Mercury 125 hp and apparently the shift shaft was moved prior to install so it would not shift to all three positions (stuck in Forward gear).

So, I removed the lower unit and tried to find each gear position by rotating the shift shaft. I moved the controls to the neutral position. I put the shift shaft in the neutral position and reinstalled the lower unit.

I put control shifter in forward gear and the prop shaft rotated clockwise with ratcheting sounds and would not rotate (locked) to the counter clockwise position.

Shifted to neutral and prop shaft spun in both directions freely.

Shifted to reverse and the prop shaft would not rotate in either direction when rotated by hand. It was locked.

I read the manual and it does not specify if the prop shaft (when in reverse) should rotate counter clockwise. It just says that the prop should lock when attempting to turn clockwise.

I always thought the prop would spin counter clockwise and not rotate clockwise. The way it is now, it does not spin at all.

What is the correct function of the prop shaft as it relates to the shift shaft position (specifically in reverse)?
Should the prop shaft spin counter clockwise (and lock clockwise) when the gear case of lower unit is placed in reverse?

 

[GA_Boater]

You just explained normal operation. Forward has a dog clutch that clicks in one direction.

Reverse has no clutch so you are trying turn the motor. If you try hard enough it will turn in both directions but you better eat Wheaties topped with spinach.

 

[bighermHK45]

You just explained normal operation. Forward has a dog clutch that clicks in one direction.

Reverse has no clutch so you are trying turn the motor. If you try hard enough it will turn in both directions but you better eat Wheaties topped with spinach.

Thanks for the reply. I could of sworn my old 1998 Mercury 115 2 stroke (similar motor) allowed the reverse to spin ccw. That is why I was concerned when this outboard did not behave the same way. Is it possible the Merc 115 had worn parts to allow the reverse to be spun by hand, or is that not possible?

 

[djrowe007]

Some gearcase lock both ways, new gearcases ratchet one way and lock the other. The reason for this is when you go from wide open throttle forward gear to neutral the boat doesn't take a nose dive. If the gearcase doesn't ratchet it will slow down boat much faster because the prop doesnt spin. As long as it shifts when engine is running don't worry about it.

 

[bighermHK45]

Some gearcase lock both ways, new gearcases ratchet one way and lock the other. The reason for this is when you go from wide open throttle forward gear to neutral the boat doesn't take a nose dive. If the gearcase doesn't ratchet it will slow down boat much faster because the prop doesnt spin. As long as it shifts when engine is running don't worry about it.

Yeah, I am learning about all sorts of differences in the various outboard gear cases. I wish there was a list/source document that identified all the respective functions.

 

[djrowe007]

What you need is the service manual for you engine, get your serial number and call a local Mercury dealer and they can order it for you. Most likely $50 - $75. Then you shall know all you desire on your engine.