alpha one - drive shaft dropped.

[adameverett]

Hi,
I am a newbie, I wonder if someone can help point what may be wrong.

I have a '86 merc alpha one drive, of which I want to repair for a restoration project.

the lower vertical gear box drive shaft has dropped a 1-2mm. This is causing an un-even gear grinding you can feel when you turn the shaft by hand.

What could be wrong? why would the shaft of dropped? I can pull the shaft up and turn it and it feels smooth.

when the shaft is in the dropped position it doesn't sit in the top tapered bearing, so has some side play. When I pull it up it it seats in the tapered bearing and all feels a snug fit.

 

[rodbolt]

Re: alpha one - drive shaft dropped.

its normal, when running the gear load pushes the driveshaft up against the bearing.
on units without the preload pin at the top of the driveshaaft you get all kinds of play whith the water pump removed.