Shouldn't be any problems unless you want to run it long periods. If you can
remove the damaged plug without dropping the porcelain into the cylinder and
scouring the walls. It will of course run inefficiently and will have to
carry those extra parts and their movement. The fuel will still go into the
cylinder and of course not be burnt, then creep down past the rings and into
the oil. This should just burn off when you reach higher temps, but an oil
change wouldn't hurt, or a oil additive. You should be ok. Correct it
immediately though. Don't go water-ski until it is fixed.










"jim" wrote in message
...
Hello,

Just took the boat out and was running fine until i lost major power.
Couldnt go above 3k rpms. Checked the merc 3.0 and saw one spark plug
cable off. So i grabbed it and received a hell of a jolt and noticed the
spark plug had actually broken off clean. Anyone see this happen before?
Any damage by running on 3 cyclinders for about an hour?

TIA!