No reverse day after lower unit instal - Mercruiser

[Starcraft Enterprise]

Yesterday I removed my lower unit and replaced the drive shaft seals, shifter seals and impeller. Reinstalled unit and took on a 1 hour test drive at various speeds and shifted from forward to reverse several times. Today I get off work, go into the back yard, jump in the boat, try to back out of the dock and nothing. No reverse. Engine revs, no clunking or grinding, just neutral. Pushed away from the dock by hand, forward and neutral work just like normal. Went ahead and took off to see if anymore symptons presented themselves. Drove around for about and hour, tried several more times to use reverse, nothing changed.
What could I have done wrong?
After a search of this section the only thing I came up with was I did not put unit in forward before removal and installation. But it worked fine yesterday? I had the usual 1 inch gap issue during reassembly where you have to wiggle and realign averything, but it seemed to go together ok.
Is it just a coincidence that I had it apart yesterday?

All original 1969 Mercruiser 120.

 

[Fishermark]

Re: No reverse day after lower unit instal - Mercruiser

My first thought would be that you forgot the ss washer on top of the lower shift shaft.... but since it worked yesterday... hard to tell. If you disconnect the shift cable, can you shift it into gear by hand?

 

[Starcraft Enterprise]

Re: No reverse day after lower unit instal - Mercruiser

I read about that stainless steel washer in the other posts, but I don't recall mine having one. Could that be because, according to the Seloc manual, mine is a generation 1 Alpha and I seen from the pics that the generation 2 is different?
I was too tired to pull it from the water and investigate shifting by hand (work third shift). Thought I would post question first before tearing back into it again for a direction to go with it.

 

[dubs283]

Re: No reverse day after lower unit instal - Mercruiser

if the washer isn't there it is possible that the drive shifted for one day then the shoe wiggled down just far enough to not be in the fork

without the washer at first it will be engaged enough but the bottom of the shoe assy is probably wearing on the top of the shift shaft seal and has now dropped out of the fork

you need to pull the boat and check for that before you possibly cause more damage to that seal

 

[stonyloam]

Re: No reverse day after lower unit instal - Mercruiser

There are only two things that usually go wrong when you remove and replace the gearcase (lower) the intermediate shaft is indexed incorrectly on the lower shift shaft, when that happens the control handle jams. Not your problem your control is moving freely. The other is not installing the stainless steel washer on the lower shift shaft. That allows the intermediate shift shaft to drop down and uncouple from the upper shift shaft. Handle moves freely,but no shift. That could be your problem. The intermediate ss may have dropped enough that it is barely making contact, and disconnects when you try to go into reverse. Raise the outdrive part way up and see if the top of the intermediate ss is fully seated into the bottom of the upper ss. If you only dropped the lower it does not matter that it was not in forward. Also you could try readjusting your shift cable to make sure that is correct. Good luck.

 

[Eric 3.7LX Alpha 1]

Re: No reverse day after lower unit instal - Mercruiser

If that washer was missing on reinstallation, this is what dropped in the picture. Pic from Ziggy. These shift shafts came apart.

 

[chaparall villain 2]

Re: No reverse day after lower unit instal - Mercruiser

i would say the shoe went in crooked and slipped i would pull it out and put the boat in forward slide it back enough to realign the shoe and then back in then recheck reverse while on dry land and see if it engages .... good luck