I recently purchased a yamaha 25hp 4 stroke motor. The motor has a noise in it and i was told that a 4-stroke should be quiet. My question is could it be the rod bearings. Someone told me that these motors had problems with the rod bearings.
never had an issure with rod bearings.
that motor was a merc design, 2 cylinders with 3 pistons.
the 3rd piston was a balancer nd tended to make noise.
without hearing the noise its hard to say.
does the noise change when you kill a cylinder ?
I have a yamaha 25hp four stroke outboard also and I hear a strange knocking noise from it. I suppose that the source of noise is the harmonic balancer. I was told by the dealer that I need to replace it.
1999 Yamaha 25 hp 4-stroke
Linear Mode
