Re: 85 200HP V6 mariner ignition/stator?s
There is also a buzzer that starts going off if u go full throttle more than about 15sec . If u hold it at around 3500RPMs it will go all day. What do y'all think
How old is the water pump and impeller?
Load increases with RPM, which increases the cooling demand. A marginal water pump impeller and/or worn housing can flow enough for part load yet fail to supply adequate cooling at WOT.
Another possibility is leaking head gasket(s), they can hold cyl pressure at moderate load yet leak combustion gases into the cooling system at WOT loads, displacing water and the temps rapidly climb.
Both are assuming that you have a solid tone temp alarm.
If you have a rapid beeping oil alarm then it could be as simple as a misfiring spark plug or wire on the coil that is wired into the oil alarm, usually #4.