Thread: 120hp I/O

i have a 120 hp i/o and when it gets warmed up it makes a loud tapping noise when i give it full throttle i was told it might be the water baffles in the exhuast and not to worry about it can anyone tell what it might possible be? its a chevy marine engine and mercruiser drive unit

what isn't my question important enuff for someone to answer???????????

Very few people here use I/Os. I've had a few over the years but not that much experience working on them like outboards. If it were a car I'd say you have a lifter or a rod knocking but its really very hard to say without being there to hear it first hand.

first off i want to know how a water baffle will make a tapping sound ....sounds like internal engine problem ....if its been sitting a while could very well be a lifter...thats definately must be there situation you got ....good luck

Originally Posted by crappie_mad_man

i have a 120 hp i/o and when it gets warmed up it makes a loud tapping noise when i give it full throttle i was told it might be the water baffles in the exhuast and not to worry about it can anyone tell what it might possible be? its a chevy marine engine and mercruiser drive unit

Could be spark knock. Are you using low octane gas and how old is it? You might want to try fresh high octane and see if that helps. Billy