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Johnson 15 Lower Unit Problems

jdkline

Regular Contributor
" The lower unit on my 1990 15

" The lower unit on my 1990 15 HP Johnson finally gave up the ghost last week, so I went out and found a used gearcase off a parts engine. The guy I bought it from is a reputable mechanic and said the gearcase was in good condition, so I took it. When I got it home, it appeared to me that the driveshaft was in somewhat rough condition. I pulled that shaft out and inserted the one from my old unit. They are exactly the same and this one appears to be in better condition. I noticed that when I inserted the droveshaft, unlike on the old lower unit, I could not turn the shaft in such a way as to make the propshaft turn. I figured that maybe it wasn't engaging the propshaft, but when I put it on the boat, it would engage in reverse, but not in forward. In fact neutral also works, buit not forward. Did I get a unit with a bad forward gear? Is there some other explanation? Thanks for any help.
J.D. "
 
"JD.... The driveshaft does no

"JD.... The driveshaft does not engage the propshaft, the splines on the driveshaft engage the pinion gear splines. If the unit happened to be in neutral, turning the driveshaft would not make the propshaft turn.

The shift problem may simply be that you do not have the brass shift connector aligned properly. The 3/8" hex head retaining bolts should line up with the groove on the upper and lower shift rods. Double check that linkage.

Joe
"
 
" Joe, I'm not positive, b

" Joe, I'm not positive, but I'm pretty sure that the grooves are lined up. Am I correct in thinking that if the driveshaft were not engaging the propshaft that I would also have no reverse as well as no forward? Could it be that the shift rod is sticking? How do you get the lower shift rod off on one of these engines? Can it be done without disassembling the lower unit? "
 
" Joe, if he switched drive sh

" Joe, if he switched drive shafts would it not need to be re-shimed, Just curious? "
 
"Walkabout.... The driveshaft

"Walkabout.... The driveshaft on the 9.9hp and the 15hp are strictly a slide in shaft. Removing the water pump allows the driveshaft to be slid out of the lower unit. No shiming involved.

Joe
"
 
" Thanks for all the input. I

" Thanks for all the input. I hope that I hnow have the problem solved. Apparently, the shift rod was just sticking and it was ahrd to get the motor into gear. Hopefully it will be relaible, i still need to test it on the water.
J.D. "
 
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