1979 115hp clatter

[Sherman]

My engine has developed a clatter between 1100 and 1500 rpm. It sounds like something loose in the rods or piston it seems to shake a great deal in the same rpm range. It runs great at idle and high speeds. Any ideas.

 

[buddyholly]

Re: 1979 115hp clatter

does it shake and rattle in gear or in nuetral? also, do you have the hood off the motor when it is doing this? could it be a loose motor mount bolt or something on the outside of the motor. i had the same shaking when idling and at lowto mid rpms. i found that the choke was sticking on and at high rpms the throttle linkage open the choke but at lower it would let it go closed. just trying to offer some help. good luck, bob

 

[Sherman]

Re: 1979 115hp clatter

Thanks I'll check those things out. <br /><br />Sherm

 

[KYHunter]

Re: 1979 115hp clatter

I had a very similar problem with my 115 johnson . When I first got the boat it sounded great to me, but what did I know? After a few times at the lake I started to notice an almost inaudible clatter type noise that would seem to go away at higher rpm's. I thought, well its an older motor , probably just a little tired. Wrong, dropped a cylinder, piston seized. After the breakdown I started to think about it and I believe the sound was there the whole time just that the ticking/clatter sped up with higher rpm's. Making it harder to pick up , between the engine getting louder and the ticking faster at higher rpm's. Just my thoughts, may be completely wrong, but kinda makes sense. I would do a thorough check before I ran it again. Compression test , fuel flow, spark etc. I'm no expert but better safe then sorry, as I was. One other thing , now that I've rebuilt my motor , I really see the difference in how the motor runs . It was really shaking badly before the problem , I just didn't know it , without having anything to compare it to. <br /> Good - Luck,<br /> KYHunter