overheat on ful throttle only

[coreyjm75]

94 85 hp overheats on ful throttle only,new water pump,head gaskets waterplate gaskets and cleaned head like new,please help!!!

[boats.net]

If didn't replace whole water pump then may need to replace hosing and a water pump repair kit. Check thermostat and pressure relief valve.

[FLDAVE02]

Corey:

Had the same problem after 18 years on my '94 75hp. The water passages were "Rocked up" with calcium. Tried all the Lime-away products. Not very good results. Diluted masons grade Muriatic acid 50%. Pulled thermostat and pressure relief valve. Let idle for half an hour in a tub. Flushed for an hour with water. Replaced thermostat and PRV. Did the trick. No more over heating. Yooho!

Good luck, Dave