somethings amiss on my Johnson 40 hp

[hookups08]

Good morning all,

I have a 1960 Johnson 40 hp and I am having some issues. I just got it back from a pretty poor excuse for a mechanic but either way, the motor is running just fine and at minimal speeds I can till around just fine, its when I increase the throttle and my speed does not increase, it seems water bubbles more but I dont feel my prop is turning properly. My motor revs up and it sounds pretty good, I just dont go anywhere...any suggestions?

 

[Daviet]

Re: somethings amiss on my Johnson 40 hp

If the engine is running properly, not missing, and the RPM goes up but the boat slows down it is most likely a spun prop hub.

 

[hookups08]

Re: somethings amiss on my Johnson 40 hp

whats a spun prop hub and how would one go about fixing that?

 

[Daviet]

Re: somethings amiss on my Johnson 40 hp

Your prop has a hub that is driven by the drive in, some people call it a shear pin. That hub is pressed into the prop, after a period of time the hub can deteroriate and start to slip.
Remove the the prop nut to expose the drive pin, scribe or mark a line on the prop to match the drive pin and install the prop nut. Test the engine in the water and when it acts up recheck the scribe mark and if it is not still aligned with the drive pin the hub has slipped. Remove the prop and have it rehubed.

EDIT: If you have access to another prop, try it and see if the problem goes away.