Johnson 35hp 1977 weird noise

[suicida]

Hello everybody,

I have a Johnson 35 Hp outboard 1977 with electric start and sometimes when it's at idle and high speed it's doing a weird noise, a sort of thumping like it hits something and momentary lose power. Any idea about this problem?Can i fix that easily?

Somebody told that maybe i have to clean the carb.

Finally, the battery charges when the engine runs?

Thanxxxx!!!

 

[samo_ott]

Re: Johnson 35hp 1977 weird noise

If you're at high speed and it feels like you hit a log and revs and then kicks back into gear it's usually your shifter clutch dog in the lower unit. You'll have to open it up and check. You could try adjusting the linkage first though, I'm not 100% sure on your engine but usually the adjustment is behind the shift lever.

And if it is doing that, stop using it and you'll shred your gears in the LU.

 

[5150abf]

Re: Johnson 35hp 1977 weird noise

Yes the battery charges when the engine is running , still a good idea to throw it on the charger now and then.

This thumping happens both at idle in gear and at full throttle, is it worse at full throttle like you are hitting a stump or something in the water?
If you can be more descriptive, sounds like it could be a clutch dog.
Describe the thump better and what the motor does when it thumps.

 

[suicida]

Re: Johnson 35hp 1977 weird noise

The thumbing happens when it's running in gear and in neutral position. At full throttle is getting worsed (more intense). Yes, it's like hitting something in the water and the whole motor vibrates and i think that loses some of its power. At low speed this happened less. The thumbing happens randomnly.

 

[5150abf]

Re: Johnson 35hp 1977 weird noise

If the motor thumps when it is running in nuetral your lower unit is toast, that indicates that a peice of metal has broken off and is getting caught in the gears.
Drain the lower and see how much metal is in it.(2 straight head screws,right side, one on the bottom one about a foot above,remove both)
The way the lower works the gears are always turning and the clutchdog slides in between them and engages forward /reverse, so if it is thumping with out being in gear there is something floating around in the oil.
Post again with what come out, I would geuss mostly water.

 

[F_R]

Re: Johnson 35hp 1977 weird noise

I suspect you have two different and unrelated problems. (Maybe). The one at idle could be what's called a "lean sneeze", actually a muffled backfire into the crankcase caused by running too lean on the fuel/air mix. Try adjusting the carb slow speed needle a tweak toward rich and see if that clears up.

But the bad news is that at high speed it is the clutch dog and forward gear. It is coming out of gear, rotating a half turn and slamming back into gear. You better have a full pocketbook for that one. (No, they don't lean sneeze at high speed).