drive shaft lock-up in '75 25HP

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vicksburgbillie

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Oct 19, 2009
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My cousin recently gave me a 1975 25HP Johnson w electric start but electric start is disconnected. The engine had overheated and stalled out after the impeller failed - thats why he gave it to me. The engine would shift to neutral and turn over and the prop would turn prior to my replacing the impeller. After replacing impeller it seems that the drive shaft is locked in place. The shifter works and the shift rod moves up and down but it does not seem to go into neutral - i.e., when you shift to neutral and attempt to crank the gears appear to be locked up. If I drop the foot again and disconnect the shifter - you can shift to neutral or F or R by pressing up or down on the unattached shift rod. Also, the engine will turn over. It feels like the drive shaft is pressed too firmly into place when the foot is fully attached. What have I done wrong in reassembly? Can anyone offer advice or suggestions? Thanks. :confused:

Ed
 
H

HybridMX6

Senior Chief Petty Officer
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Oct 22, 2008
Messages
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Re: drive shaft lock-up in '75 25HP

did you happen to adjust the shift rod height on accident during removal/install? If so, it is probably not getting out of gear now. They have to be set at a specific height to shift properly, or you get stuck in a gear.
Can you spin the prop by hand when the foot is dropped? Same for the drive shaft? Wondering if the impeller is jammed or something if it's not the shift rod height.
 
jasper60103

jasper60103

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Sep 18, 2008
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Re: drive shaft lock-up in '75 25HP

Yea, it sounds like your drive shaft height has changed. Did you put grease on top of the drive shaft? I heard that can cause problems. Only lubricate the splines on the side.
Also, did you remove the drive shaft from the foot when you replaced the impeller? If so, hopefully no obstructions fell down in there.

edit: Second thought. It sounds like somethings wrong with that shifter linkage. Make sure you have bolt (6) lined-up with indent in shift rod (24).

lower.jpg


vicksburgbillie said:
My cousin recently gave me a 1975 25HP Johnson w electric start but electric start is disconnected. The engine had overheated and stalled out after the impeller failed - thats why he gave it to me. The engine would shift to neutral and turn over and the prop would turn prior to my replacing the impeller. After replacing impeller it seems that the drive shaft is locked in place. The shifter works and the shift rod moves up and down but it does not seem to go into neutral - i.e., when you shift to neutral and attempt to crank the gears appear to be locked up. If I drop the foot again and disconnect the shifter - you can shift to neutral or F or R by pressing up or down on the unattached shift rod. Also, the engine will turn over. It feels like the drive shaft is pressed too firmly into place when the foot is fully attached. What have I done wrong in reassembly? Can anyone offer advice or suggestions? Thanks. :confused:

Ed
Click to expand...
 
V

vicksburgbillie

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Oct 19, 2009
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Re: drive shaft lock-up in '75 25HP

HybridMX6 said:
did you happen to adjust the shift rod height on accident during removal/install? If so, it is probably not getting out of gear now. They have to be set at a specific height to shift properly, or you get stuck in a gear.
Can you spin the prop by hand when the foot is dropped? Same for the drive shaft? Wondering if the impeller is jammed or something if it's not the shift rod height.
Click to expand...

Thanks for helping. I did not intentionally adjust shift rod height. It could be that the shift rod is not exactly in the same place as suggested by the response just after yours. The prop will spin when the gear case is dropped just a few inches and the shifter moved to neutral position; and the engine will turn over when the drive shaft is disconnected. I dont think the impeller is jammed because i checked it prior to completing installation and it turned in the housing with just a little extra effort.

thanks again for any help you can offer.
 
V

vicksburgbillie

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Oct 19, 2009
Messages
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Re: drive shaft lock-up in '75 25HP

Thanks for your help jasper60103.

I did not remove the drive shaft from the gear case. You may be right that the shift rod is not exactly where it was originally. However, once installed and it seems to be too tight - it will shift thru the 3 positions but does not act as if neutral is there. It really does seem that the drive shaft is pressed too hard in its connection.

Also, i did not add grease to the top of the drive shaft but i did put gear case lubricant around the splines and the o-ring.
 
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