any trick for putting a lower end back on?

[Natedogg86]

My old man and i recently bought a 79' weekender with a 260 mercruiser. we removed the lower unit of the the out drive to have work done on it, replacing water pump, pressure test, etc. we got the unit back and are having trouble getting all the gears to line up putting the thing back on. any little tricks of the trade or help anyone can offer would be helpful. boating season is here and we're egar to get it in the water.

 

[SCORPIO]

Can you elaborate on what you mean by 'getting all the gears lined up'? Do you mean that it won't shift or that you can't align the splines on the lower with the upper, or do you mean the shift shaft won't line up?

 

[Natedogg86]

There are two gears on the lower unit one is the drive shaft the other is a much smaller gear that i believe is for the transmission, i don't know i could be wrong. we can get the smaller gear to line up but not the shaft. we had to put the engine in gear to take the lower unit off and im wondering if it should almost be in the same gear to put it back on. unfortunatly the throttle got moved around a little bit while the lower unit was being worked on and im wondering if that's a problem or not. im mechanically inclined and have gotten everything on this boat working and ready to go and this is just frustrating the heck out of me.

 

[andyr]

Make sure throttle is in forward. Look up behind upper outdrive looking aft and the shift lever should be straight aft. This is the top of where the little gear seats. With the propeller on the lower unit, put the lower unit in forward gear by rotating little gear i.e. the shift shaft clockwise while rotating the prop in reverse, counterclockwise. It should lock. Lift the lower unit into place. Don't let the prop rotate clockwise a bit. Trick: as you lift into place, rotate the prop a hair counterclockwise to rotate the shaft to align the power shaft with the upper gear and it will come up the last inch. Once it is in place check by shifting into neutral, fwd and reverse and seeing that the prop will move only the right way. Don't forget or bump the oil seal that mates between the upper and lower units. Also check that o ring that is on some alpha shafts didn't come off and is stuck in the upper housing.

 

[SCORPIO]

What does that o-ring do on the driveshaft? It seems redundant since the shaft ifts thru a pair of seals. I just did my waterpump on my Alpha last weekend and that old oring was stuck up in the seals. I had a long set of needlenose pliers that I could grab it with and remove it. That little quad ring looks like a failure point to me. I think there could have been a better designed seal or just have two seperate gear cases each with its own fill and vent plugs. OMC did that for decades.

 

[Natedogg86]

sounds like it will work. ill know this weekend and repost let u know 2 know. thank you. we already replaced that o-ring btw. thanks both of u.