My '99 3.0 mercruiser makes a popping noise when engine gets hot ( weeds wrapped around drive). But it also makes the random noise when I have a full load in the boat and engine is at normal temp at higher rpms. Mechanic who put in new water pump last year said that would fix it but it hasn't. Almost sounds like valves but a little different. I let out some of the oil ( was over filled) and that seemed to help some.
Thanks
Thanks
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