Motor Problem

[walleyeslammer]

Hello Everyone,

My dad purchased a 1978 20 hp Mercury Outboard a couple years back and now we are having an issue. The motor is running great, but when we give it throttle, we can hear the RPMs increasing, but the boat is not being pushed. It is almost like the drive shaft is spinning inside the propeller and the propeller is only slowly spinning. Does anyone have any ideas on what is wrong with the motor and more importantly, what do we do about it. Thanks in advance.

[Finns]

When that happened to me it was a 'spun prop'. Got it rebuilt for about thirty dollars (down here).

[magnum mike]

+1 for a spun prop hub