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74 mercury 110 model 9.8hp

M

merccrazy

New member
Had to replace the main drive shaft on my about 1974 mercury 110 9.8hp but i am having trouble putting the bottom end back in. Does anybody have a how to manual or can help me with why the main drive shaft assembly doesnt seem to go back in correctly?

Thank you
 
Turn the motor upside down. Using a mini flashlight, see if the shifter coupler coming from the power head is centered. If not, push it centered and jam some paper in there to keep it that way. With the shifters both in forward, slip it together. The first thing to fight you is the driveshaft entering the crank snout. Turn the prop to get it together. That last 1/2 inch is the shifter engaging. DON'T force it together since the shifter goes only one way (and if it jams, you'll pull the shifter shaft out of the lower unit getting it apart). And don't forget that water tube or you'll have to do it all over again.

Jeff

PS: If there's an O-ring on the top of the driveshaft, throw it out and lube the splines with grease. That O-ring fights you getting the thing together.
 
But on some of these motors the splined hole in the crank is not blind.----Goes right into the crankcase.-----They need that o-ring in place.
 
Well, ---Perhaps you are not aware but I have looked inside more than 1 of these wonderful motors .------On some 7.5 / 9.8 models the hole in the crank goes into the lower crankcase and they need that O-ring !!
 
I've worked on at least 3 dozen of these old Mercs and never saw that hole in the crank. That O-ring's sole purpose is to seal the crank splines from corrosion damage. The motors run identically with and without the O-ring (but are easier to reassemble).

Jeff
 
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