Damage from unsecured driveshaft bearing, Mercury alpha 1 gen1 lower unit

**waveskimmer** · 04-09-2021, 03:33 PM

Hi,
While changing the waterpump base I noticed some serious play at the driveshaft bearing. I could pull up on the driveshaft about 1/32" and the bearing would seat in the race and most of the play would disappear. It seems the retaining nut hadn't been tightened enough to seat the bearing in the race. My question is, what kind of damage can I expect to find when i crack open the gearcase?

Thanks!

**25two.stroke** · 04-09-2021, 03:38 PM

Was the driveshaft nut loose? Single bearing driveshafts (both gen1 or gen 2 alpha drives) should have serious play in that driveshaft bearing like you described. On single bearing shafts as they rev up the fwd/rev gears push the pinion and the driveshaft upwards, seating it into the bearing race/cup. The retaining nut should have a good amount of torque (forgetting the spec right now) so if its loose that was a problem.

**25two.stroke** · 04-09-2021, 03:40 PM

If that nut backed off and the bearing/shaft rose up too high then you could chip the teeth off the pinion gear or wear some grooves in the pinion. You could also jack the pinion bearing but that would not happen from 1/32"

**waveskimmer** · 04-09-2021, 03:49 PM

Thank you for the quick reply!! That's great news. The nut isn't loose at all. I ordered the wrench so I'll check the torque.

**waveskimmer** · 04-09-2021, 03:55 PM

Originally Posted by 25two.stroke

If that nut backed off and the bearing/shaft rose up too high then you could chip the teeth off the pinion gear or wear some grooves in the pinion. You could also jack the pinion bearing but that would not happen from 1/32"

Thanks, didn't notice any metal in the drained gear oil or on the plug.

**25two.stroke** · 04-09-2021, 04:18 PM

You are the 4th person whos inquired on that in the last week! All good. Hope this helps

Nut in question is called "bearing retainer" in the following.