8hp mercury 2 stroke prop problem

I have a 1980's 2 stroke outboard mercury 8 hp that has ram great for 2 years. Just recently I was using it when at about half speed when I am accelerating and it is as if the propeller gets loose and doesn't rotate, but the engine still increases its RPM's. The engine runs great and starts every time. I do not know much about the lower units, but I would suspect that the problem would be there. Maybe the prop connection is loose on the inside. Suggestions?

More than likely it's the prop hub itself that is shot.

The prop is two different pieces - the hub which fastens to the prop shaft and then the prop itself which is connected to the hub by a rubber sleeve.

It's a friction/press fit designed to slip if you hit a solid object. The rubber can wear out, crack, shrink etc as time goes on.

At least you want to hope that's the issue. The alternatives can be considerably more expensive.

So I would start by investigating the prop.

Put a mark on the hub itself and a mark on the prop adjacent to each other. Go out and flash her up until you notice the "slip" and then check the marks. If they are no longer lined up, get the prop "re-hubbed"..

Thanks for the reply, I will check on that. In the meantime, what other problems could it be?

It is the prop that is bad !!---------It is the prop that is bad.

You can see that it's the prop (which it is) by marking the inner and outer hub. Scribe a line then running it; the lines will no longer line up.

Jeff