Hi, i have a 1973 johnson 20 hp outboard..gearbox problem? help!!?

Question

This motor starts easy and runs great in nuetral, when in water in forward every 5 seconds the motor will give a hard shunt(like a hickup) the more power you give it the bigger the shunt, at low speed hardly noticable, maybe gearbox/propeller problem, can aybody help pinpoint the problem!!! Thankyou Andrew.

Answer 1

the dog clutch in you gearbox will be worn. drain the oil and check for metal in it. a lot of metal means worn dog clutch. it will jump in and out under load. cheers

Answer 2

I have a Johnson  1973 6hp this sounds more like in the motor or coil problem i would think if the gearbox or shaft was bad it would make noise all the time. I might not be understanding your explanation, but it sounds like it's missing. you don't says it jumps out of gear that's other reason i don't think its in the drive-train. Try changing the coil and tune up maybe even the head gasket. The only other way to know for sure, is to take it apart.

Answer 3

I agree this is engine, not gearcase.  Miss in the spark somewhere, or contaminated gas.  Check sync and link procedure to make sure you're not opening the throttle plates too early, or too late.  Look it up.

Answer 4

Sounds like you need a new set of plugs, through wear the gap becomes to great for the spark to ignite the fuel

when you move your throttle more open to go faster the extra fuel floods the spark

try this first anyways as plugs arnt expensive

its a matter of working your way through the problem

post again if this doesnt fix it

Answer 5

Sounds like your lower end gears are giving up. Its a common problem with the Johnson brand. Good news is 10 HP and up will fit it.I had same problem. If you find a used lower end make shur you get the prop with it. The splines will be different.

Bill

Answer 6

i had one of those once with the same problem- mine had electromagnets in the lower unit which pull it in and out of gear - pulled it apart, cleaned everything thoroughly, put it back together w/ silicone and it worked fine -if you do it, check the water pump impeller while youre in there

Answer 7

Check for water or dirt in gas. Check plugs and coils. If engine has been sitting not run in 2 years or more, overhaul the carb. I think its got dirt or gum in the jets.