20 hp merc not shifting

Jwindle89

Recruit
Joined
May 3, 2016
Messages
1
Howdy all, first off this is a great forum with a ton of information and helpful people. Im a first time poster and am completely stumped with my current situation. Allow me to elaborate. I have a 1969 mercury that runs great, only problem is it was blowing some exhaust from where the lower unit and upper u, it mate. I pulled it apart to inspect and on putting it back together, it now will not shift out of forward. I'm sure I probably was not careful enough and things became misaligned. The lower unit will spin either direction freely, as soon as it is mated to the upper half it refuses to shift out of forward. I have taken it apart probably 20 times and tried different ways of aligning, but still nothing. The shift shaft is rotating just no shifting. Any advise would be so grateful!
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
There is a splined coupler connecting the shift shaft and shift rod. When you reassembled you didn't notice that it had turned so now it is not 'indexed' correctly.

With the gearcase removed, use a pair of pliers and turn the splined shaft. You should 'feel' the detents that lock it into position in Reverse and another for Neutral. You can tell which gear it is in by turning the prop. Reverse will turn the vertical shaft. Neutral will spin freely. Either position can be used for reassembly, the control MUST BE THE SAME. Some prefer using Reverse so they can turn the prop/vertical shaft to align with the crankshaft. Some prefer to turn the flywheel. End result is the same. Verify shifting once finished to be sure you have it correct.
 
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