I own a 1985 SeaRay 260 with a Mercruiser 350, 260HP V8 engine. I was cruising at ~3800 RPM for about an hour when all of a sudden the engine appeared to skip, then proceeded like normal. Over time the problem became worse and in a period of about half an hour is was knocking regularly at idle. The knocking sound was the same whether the outdrive was engaged or disengaged. It's been a while since I did a tune up so I changed all of the usual suspects (plugs, wires, coil, fuel filter, distributor cap, rotor). I also sprayed the carb with air and then carb cleaner thinking it might have been water in the gas. None of that helped and the knocking sound continues. One clue is that the sound gets faster as the RPMs go higher. The knocking happens about 3 times per second when idling. The sound also seems to be coming from the starboard side of the engine but it's tough to tell.<br /><br />I visited a trusted mechanic who mentioned several other possibilities including broken gears on the upper part of the outdrive and major engine issues (pistons/cylinders/rocker arms/etc...)<br /><br />I would be grateful if anyone who can help or has encountered a similar situation sends me an email or replies to this message.
