72 Merc 50 HP lower unit

Nick Price

Recruit
Joined
Aug 21, 2002
Messages
2
I have just removed the lower unit of this motor to have a look at the water pump/impellor and had some difficulty. It dropped initially about an 1/8th of an inch but I finally got it right off with bits of wood and an axe! Difficulty was that the shift shaft is stuck/rusted into the upper unit and pulled out of the lower unit as it came down. (The impellor rubber had separated from the central brass bush which was why there was no water ciculating).<br />I tried to use heat on the upper end to loosen it but the fitting there started to burn.<br />Presumably the lower unit will have to be rebuilt to put in a new shift shaft, which I can get, but first I need to get the old one out.<br />Any ideas?<br />Thanks :confused:
 

tmcalavy

Rear Admiral
Joined
Aug 29, 2001
Messages
4,005
Re: 72 Merc 50 HP lower unit

If your shift shaft is stuck in the upper leg, I would soak it for a few days/weeks even with penetrating oil such as PB Blaster (auto parts stores), then clamp a vise grip on it and gently try to coax it out/down with a hammer. If its toast/rusty to begin with, you might find a used lower unit on ebay for less than what a new shift shaft and rebuild will cost for the old. If your lower unit seals are good (they keep oil in gearcase free from water contamination), I'd think about just having the water pump/impeller and shift shaft done at a shop. The pump/impeller isn't hard to do, but you need special tools for the shafts, etc.
 

Nick Price

Recruit
Joined
Aug 21, 2002
Messages
2
Re: 72 Merc 50 HP lower unit

Thanks for the advise. I have started down this track (vice grips and hammer) but didn't have much time and didn't soak it for long either. Will keep trying.<br />Oily
 
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