overheating of F150 4 stroke

[southcarolinaboone]

I have twin 150's and the temperature varies widly on one of them. Plenty of water out he pee hole but the temp will sudedely rize to the alarm point. Only happens at idol. If I speed up engine a few 100 rpm's the temp goes down rapidly. I can then reduce the idol and temp will be fine for a few minutes to a few hours. Suspect a sticking thermostat?

[99yam40]

Check/clean the pressure relief valve( PRV) while you are at it, as that will cause a low RPM overheat if it is stuck open.

[axolotl98]

I agree. Replace the poppet valve

[southcarolinaboone]

thanks to both of you...will try the popet valve as soon as I can and repost results