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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4724
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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Have 2000 15hp mercury which i use , some time

Customer Question

have 2000 15hp mercury which i use for trolling , some time ago stopped shifting into reverse . I did not pay attention to it , because did not really need reverse for trolling . Now shifting into forward stopped . Shifts only at high RPM
Submitted: 2 years ago.
Category: Boat
Customer: replied 2 years ago.
linkage is tight . moves up and down in the same pattern , i can tell that because i see the way it polished going into lower unit and out
Customer: replied 2 years ago.
shifts by remote control ( commander 2000 i think )
Customer: replied 2 years ago.
i'm mechanically very capable , once myself disassembled Mercury Optimax 225 , replaced connecting rod and a piston , put everything all together , motor runs already for good 6 years with no problems
So i just need to be pointed in right direction to fix the problem with shifting . And if it's lower . I'll take it apart . Please tell me what parts I need to order right away
Expert:  Jeff G. replied 2 years ago.
Welcome,this question may need more than a single answer. Please post back with additional questions on this at any time.
Lets see where the problem is.
Remove the lower unit from the engine. Do you know how to do this? You'll need to disconnect the shift shaft from up top by the powerhead.
With the lower unit off Push all the way down on the shaft shaft while turning the propeller to aid in shifting. Do you get an engagement in gears?
Now pull up slightly to neutral and see if the prop spins freely. Pull up again and you should engage in gear.
If you don't get the proper engagement the problem is in the lower unit. If you get the proper engagement then the problem is in the linkages or control.
So lets try this and post back what you get, we can go from there once we have the problem somewhat isolated.
Customer: replied 2 years ago.
Sure . i'll disconnect the lower . will give you the answer in 1 hour
Expert:  Jeff G. replied 2 years ago.
Customer: replied 2 years ago.
K . Lower is down . Switching shaft moves up and down smoothly . Reverse gear though never gets engaged , I hear touching of some sort of clutch , but it never gets connected . Forward gear gets connected , but it seems to me , only when you play with propeller shaft CW and CCW
Expert:  Jeff G. replied 2 years ago.
It will only go into gear when the prop shaft is turning as the ears on the sliding shifter and the ears on the gears high center each other, so always shift while turning the prop shaft.Even turning the propshaft you don't get reverse? Then the problem is the lower unit, at least partially. It will need to come apart, which takes some special tools. How do you want to proceed?
Customer: replied 2 years ago.
no . my understanding is that drive shaft moves everything into gear , propeller shaft has nothing to do with connection . I was rotating driveshaft in order to switch into gear . isn't how it works ? I'm gonna bring my lower to local marine shop
Expert:  Jeff G. replied 2 years ago.
On the bottom of the drivesahft is a pinion gear. On the front of the propshaft is the forward gear and to the rear the reverse gear, the pinion gear meshes with the two gears. So the forward and reverse gears are always turning. The shifter is splined to the propshaft. The shifter moves back and forth to engage the gears. When it engages the forward gear it causes the propshaft to turn clockwise. Reverse is the opposite.In the center of the hollow propshaft is a cam which moves the shifter back and forth. In the linked drawing the gears are #4 & 11 and the shifter #7 you can see the splines on the propshaft. If the cam follower #6 is worn or the cam on the end of the shift shaft is worn you will lose the gear as the shifter won't move far enough.