Mercruiser Lower unit wont go back together

[jseer891]

HI I have a 1986 Mercrusier Alpha with a inline 6 motor. Yesterday I dropped the lower end to change the water pump. When I try to put the lower unit back in it won't back to together. After several tries I was able to get some the nuts back on. But with less than a quarter inch to go. The drive would not go any further. I have checked to make sure the old o ring is not stuck at the top of the shaft and there is nothing stuck on the oil passage hole either. The motor is in forward Gear. Can anyone help me here. I am getting tried of lifting this thing. Thanks

 

[ziggy]

Re: Mercruiser Lower unit wont go back together

I have a 1986 Mercrusier Alpha with a inline 6 motor

could you clarify. from a drive application chart, i show a L6 engine was not being used in 86. last use appears to be 81.
if it were my 1 drive w/L6 engine. i've always felt that what stops ya from mating the two half's is the water pipe and guide tube. they can kinda flop around. putting the pipe in the upper and the guide in the lower seems to help the most, along with some grease on the ends to help them slide together.
could be mis mated splines too. ya can rotate the lower drive shaft via the prop. ccw only to keep it in fwd. to get the splines to line up to mate..
also. you can remove the drive. putting the half's together on the bench is much, much, much, easier and can be done by yourself. when on the boat, that lower gets real heavy trying over and over to mate it to the upper..

 

[ashleygoodin]

Re: Mercruiser Lower unit wont go back together

I have an '88 Alpha One outdrive and have experienced this before. The outdrive does get heavy, but if you have a concrete pad and a good stand/blocking, that can really help.

If you are lacking 1/4", try reaching around the outdrive to the transom side and feel to see if the shifter linkage is in alignment. There is just a bit of play in the linkage and the "U" shaped channel from the outdrive may not be perfectly aligned with the lower unit. With that said, be sure that if the lower unit is in forward gear that your shifter is in forward gear. I have changed mine in neutral with no problems, but I have seen it recommended here to change in forward.

I have replaced the water pumps on both my Alpha One and a '68 Merc 1000 outboard and the water tube alignment is a real b**** as well, but a bit of grease and inserting into the upper first really helps.

Good Luck!

 

[Bt Doctur]

Re: Mercruiser Lower unit wont go back together

Whatever you do DONT FORCE IT. It slips together easily WHEN everything is lined up.
control box in fwd
splined shift shaft turned fully clockwise(fwd) and prop locks counterclockwise.
lightly grease the rubber ring where the copper tube goes in the pump
may have to turn prop counterclockwise a bit to line up the driveshaft splines
insert untill front nut catches(2 threads)
install 2 side nuts and tighten
install the rest of the nuts and tighten..

 

[Bondo]

Re: Mercruiser Lower unit wont go back together

Whatever you do DONT FORCE IT. It slips together easily WHEN everything is lined up.

Ayuh,... Agreed,... It'll get Mighty Expensive if ya do...

 

[jtybt]

Re: Mercruiser Lower unit wont go back together

The shift shaft coupler(foot/boot ) aren't lining up. Putthe remote shift in forward and lower 'foot' facing forward and wrap a bungee cord around a prop blade to force it holding in a counter clockwise position which locks the gear in forward.

 

[jseer891]

Re: Mercruiser Lower unit wont go back together

Thank for everyone's help. It was the shift shaft causing the unit no to go in.