Merc 500 shift problem

[79Glastron]

I'm stilling having an issue with the shifting of my `75 Merc 500. The main problem is it will not "lock" its self into reverse. When you shift into reverse with the control, you can still turn the prop and it won't turn the engine, it will grip, release, turn, grip, ect, both directions. When going from neutraul to forward, it will snap right away into forward, the prop will lock one way, and rachet the other way, correct. However, when pulling the control back to neutrual, and if you turn the prop, it is still slightly engaged in forward, and you need to pull it back into reverse to get it to go into neutrual detent. I have the plastic barrle adjusted all the way forward. Even with the cable removed, and me pushing back on the shift arm, it still won't lock into reverse, kinda eliminating the shift cable/control.

I have pulled the lower unit and shifted it on the bench. If it makes any difference its a square shift shaft. It will shift correctly on the bench. However, I have more travel of the shift shaft on the bench than I do on the engine. I'm starting to think my clutch assembly in the lower is worn, and not letting it go fully into reverse, and not fully into neutraul when coming out of forward gear.

I have another lower unit, but its the spline shaft. I don't have the tool to remove the shaft from the lower unit, and I don't really want to pull the power head so i can change shift shafts from my `70 500 parts motor........What do you experts think?
Thanks!

 

[79Glastron]

Re: Merc 500 shift problem

I did some more work yesterday and it looks like there is a good bit of play in the shift shaft going from the power head to the lower unit. The slop looks like its coming from where it couplers to the lower unit. I assume its the shift shaft in the upper is what is worn? I don't think the hardned shaft in the lower is worn. Does this happen with the square shafts? Anyone? Please?

 

[79Glastron]

Re: Merc 500 shift problem

No one has any input?

 

[Wingedwheel]

Re: Merc 500 shift problem

I had a similar problem. It turned out the coupler was worn. I replaced that and no problems.

 

[79Glastron]

Re: Merc 500 shift problem

I didn't realize the coupler was removable, is it loctited on the shift shaft? It looks like that part is still available.
Thanks!

 

[Wingedwheel]

Re: Merc 500 shift problem

It will probably be on there tight, mine was but not too bad. I made a tool out of flat stock with a small hook on the end. Took a pair of vise-grips to hold it and hooked it over the top of the coupler. A few sharp taps on the pliers and it popped right off

 

[79Glastron]

Re: Merc 500 shift problem

Thanks for the advice, but after looking at some parts diagrams, it looks like my shift shaft is one piece. I did find a new one, now to pull the power head. Hopefully that won't be too bad!
Thanks!