Lower unit will not go all the way in

[bpost58]

My new to me 1983 50 HP needed a new impeller. I bought the real MERCURY parts kit and replaced it all. A friend and I can not get the lower unit all the way in. There is a solid metal to metal clunk leaving about a 3/4"gap and it will not move further. The side bolts are not protruding enough to show thread. We THINK we feel the shift shaft is aligned but the lower will not go up any further. We worked on it for two hours and have given up so far.
What is wrong?

 

[bpost58]

At 7:05 AM this morning I got it to go in. Turning the engine by hand allowed the shaft-motor splines to get aligned and it popped right in. Now all I need to do is get the gosh dang it shift shaft to go into its proper spot as it is completely out of its recess.

 

[Texasmark]

Shift into F gear and slowly turn the prop ccw...the direction where you can rotate the drive shaft, not the overrun clutch direction, while "jiggling" the LU with hand pressure. 3/4" is about the length of the powerhead to drive shaft "spline" engagement....seems your teeth aren't lined up between the two.

If that fails, drop the LU and ensure the bottom of the crankshaft and top of the drive shaft are in mateable condition with no obstructions. Also check the water tube and ensure it's where it belongs...both ends since it could stay in the midsection or come out with the pump when disassembling (sometimes).

 

[Chris1956]

Nuts, keep the motor and control in neutral. Does your motor have that plastic insert over the shift rod? If so, install it in the midsection to hold the upper shift rod in place and centered.

Alternatively, Use some needle nose pliers to grab the shift rod above the midsection and align it with the lower shift rod.

Rock the throttle arm back and forth in case the shift rods are a bit out of alignment.

 

[Faztbullet]

In forward is best way to reinstall....been doing it this way for years and can slip er in before you can blink. Three step process...water tube ,driveshaft splines then shift shaft