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Johnson 35 jumps at higher RPM HELP

F

fernhew

New member
"My 1986 Johnson 35 starts gre

"My 1986 Johnson 35 starts great, idles great and runs great EXCEPT...at higher RPM it occassionally "jumps" with a thump,( don't know how else to describe the symptoms) then settles back into running well again until the next jump. I run at low to moderate RPM now so as to prevent possible damage to the engine. Any ideas as to the cause and remedy to this problem will be very much appreciated. The motor is on a 16' Mirrocraft Lake Fisherman, if that matters."
 
"James,

It sounds as if the

"James,

It sounds as if the clutch dog in the lower unit is slipping. Sometimes it feels like you have struck an object with the prop, or hit the engine with a sledge hammer when it slips.

Tony"
 
"Tony,
Thanks a million for y

"Tony,
Thanks a million for your help. I also received an e-mail from Jason that essentially says the same thing. He had the exact same problem on the exact same engine. Is this a do-it-yourself job for a very moderately skilled mechanical type, or do I need to take it to the shop?"
 
"James,
I have a 15hp on a

"James,
I have a 15hp on a 16' duracraft, had the same problem at the lake last weekend. I took the trim down one setting, fixed the problem, ran great after that, try it, it's a cheap and fun way to test, hope that helps

Kevin"
 
"Thanks, Kevin....I'll giv

"Thanks, Kevin....I'll give that a try next time out. I already have the trim all the way down, though, so I'll try moving it up one notch."
 
"James,

If you need to rebu

"James,

If you need to rebuild the lower unit, it is doable, but you should read through the procedure in a good manual before attempting the repair.

Tony"
 
"ok,i have a 35hp johnson 1977

"ok,i have a 35hp johnson 1977 year.i just bought the boat.and dont know a lot about it.i am haveing a problem with it when it is in the water.when you put it in gear it jumps or sounds like it has hit something.usualy at half speed and lower speed i dont run it at full speed.also the longer you run it,you will hear what sounds like air or steam comming from it.i saw it the last time i took it to the lake it looked liked steam.could someone tell me what is wrong?.i put a new fuel tank on it and new gas and oil.one pint to 6gal.plugs dont foul and the motor rungs great.however when i run it for a while in the water it will spit back or back fire when i try to start it.the moter has only been sitting since last season.advise and help needed thanks. larry."
 
"Larry: I think You should mov

"Larry: I think You should move this to a new thread, I'm afraid it may be long!
Start with the gearase, probably new cluth dog and forward gear wheel. When you have the gearbox down, change impeller at the same time.
Move up to the thermostat and change that as well before you check the powerpack for 'double' fireing. Probably the carbs needs some cleaning as well!"
 
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