18 hp 69 Fasttwin slipping

[Stickydan]

I have an 1969 18hp Fasttwin. The other day while motoring across the water at full throttle the outboard seemed to suddenly slip out of gear. It was still in forward gear but I could only get thrust when at low speed. When I try and throttle up I get no additional thrust, only engine revving. I'm not very familiar with outboards, and have only owned this one a short time. Can anyone help me with this and tell me what is wrong? A friend thought there is a clutch spring that is broken. Is this the problem?

[Elton Smith]

I know these old engines.It two things.THe splines in the prop are stripped out.More likely the clutch dog is rounded off.The clutch dog is what holds you in foward or reverse.You can see your part by clicking boats.net in the upper left hand corner of this page.Look for gear case.