1989, Mercruiser 3, Lower Unit drive shaft play

[Boat Show addict]

I removed the lower unit today to replace the impeller. What I found has me baffled.
(The shaft is in neutral )
When the shaft is as far into the lower unit as it will go (by its own weight) and I turn the drive shaft, it has a bumpy feeling and makes rubbing noises at each bump. Also, the shaft moves considerably from side to side and I can see the bearing moving side to side as well.
When I pull up (maybe 1/8") and turn the shaft, the bumping nearly goes away and the shaft DOES NOT move side to side at all. I would like your opinion on what might be wrong. Do I need shims, has the bearing moved on the shaft? I just don't know.
I can send a video of all this if it helps.
Thanks

 

[Bondo]

Re: 1989, Mercruiser 3, Lower Unit drive shaft play

1989, Mercruiser 3, Lower Unit

Ayuh,.. What's a Mercruiser 3,..??

If you removed the waterpump base,.. Yes, things get Loose...
Put it Back together....

 

[Boat Show addict]

Re: 1989, Mercruiser 3, Lower Unit drive shaft play

3.0 liter.

 

[Bt Doctur]

Re: 1989, Mercruiser 3, Lower Unit drive shaft play

Perfectly normal, when the gears spin ,it pushes the driveshaft upward. This sets the bearing preload.

 

[Big Boat Bay Buster]

Re: 1989, Mercruiser 3, Lower Unit drive shaft play

Just want to add, normal for an Alpha one which according to your year is what you have. A pre-Alpha is different, preload is set and the drive shaft is firm in place and has a preload pin on top. I was used to the pre-alpha and when I did my first Alpha, I too thought something was wrong!!
Chris

 

[Boat Show addict]

Re: 1989, Mercruiser 3, Lower Unit drive shaft play

BT DOCTUR and BIG BOAT BAY BUSTER thanks for the informative replies. Not only do I now know that what I'm seeing is OK but I know why..

Thanks

 

[maniogre]

Re: 1989, Mercruiser 3, Lower Unit drive shaft play

I just noticed the same exact things as the OP. I have a 1997 alpha 1 gen 2 outdrive. Came looking for answers. Great forum!!!!!!