What year do you have, or Model number?
Are you speaking of a 6 hp or a 6.0 liter engine?
Engage? The gears?
Without a year or model number, I won't get real far...
The 6hp Johnson first came on the scene over 45 years ago.....
Some models did have a shear pin and yes this would prevent an engagement of the propeller...
Remove the prop and the shear pin is easy enough to see and change...Also there should be a spare (If not already Used) either just inside the cowling or just under the engine on the outside of the cowling near the front...Also should be a spare cotter pin...
Take note to the model and take the pieces of the old pin to your local boat dealer to get another spare pin and cotter pin...
Wala !!! Yes there is a shear pin and the part Number is 324690 from Johnson
Part # 51 in diagram....remove the cotter pin #53 to remove the propeller
Remove the cotter pin # 53 to remove the propeller
Yes, I did mean to tell you. It is a 1992 Johnson 6 hp Outboard Engine
Marine Mechanic
21 Years Experience as Mechanic, 18 Yrs Boat Yard Owner/Mechanic, Factory Certified