Re: Noise at Idle
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I have a 1976 20 HP Merc that had a ticking/rattling noise at an idle and it got worse with speed. The lower crankshaft bearing was coming apart and a couple of the balls from the bearing found their way into the lower cylinder through the intake port. These were being slammed back and forth and did a number on the top of the piston, which I replaced along with the bearing. Enough metal was knocked off the raised portion on top of the piston to unbalance the motor, but cylinder walls were amazingly good. I haven’t run that motor for many years because it seemed every time I ran it, something else broke. I bought it from a friend, so know the history – it has mega-hours of fishing on it.
Dave