Need help 1979 Merc 40 HP lower unit parts

curtito

Cadet
Joined
Jul 20, 2007
Messages
6
I installed a new CMS tilt.trim on my boat and realized that I tore off the skeg last outing on the boat ramp due to low water. I decided to take the lower unit off to check for other damage. Need a new housing so ordered a complete one. However when I took off my old lower unit two pieces came falling out and I have no clue where they go. One is a yellow plastic sleeve with teeth inside but only on half of the inside (teeth match the drive shaft) and a rubber sleeve that is fatter on one end and has teeth on the inside as well. these teeth also match the drive shaft. Do these go on the upper shaft? And if so, which way and which order do they go? It is a 1979 2 cyl Mercury 40hp. I have looked through my manuals and online and can't even seem to find these pieces mentioned. Help would be greatly appreciated.
 

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: Need help 1979 Merc 40 HP lower unit parts

The plastic seal goes on the driveshaft with the splines up and the rubber goes on above it with the small end up, their purpose it to keep water out of the driveshaft splines.
 
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