1984 Mercury V150 Outboard

[hillclimber61]

Engine overheats after running one minute at 3200rpm approx 35mph. this motor is on a 1984 Ranger Bass boat. Runs very good. Replaced water pump, poppet valve(all parts) thermostats, heat sensor. Checked sensor operation. Sensor activates horn aroung 239 degrees. Water pressure stays around 10 psi. Took thermostats out and no change. So head is getting hot. When horn sounds I bring her down off plane and idle for approx 30 seconds and horn goes off. I take off and do this over and over again until i Get to my fishing spot. At 5000 rpm (55mph)it takes approx45 seconds for the horn to blow. Can anyone help. I want to get this fixed

 

[goffball56]

Re: 1984 Mercury V150 Outboard

Im having the same issue but seems when my engine runs hot it won't come out of the hole either. does your engine do this if so maybe we can both find an answer... Thanks

 

[hillclimber61]

Re: 1984 Mercury V150 Outboard

Im having the same issue but seems when my engine runs hot it won't come out of the hole either. does your engine do this if so maybe we can both find an answer... Thanks

hole shot no problems just need to fiure out overheat after a short run

 

[jimmbo]

Re: 1984 Mercury V150 Outboard

Have you pulled the heads for a look at the water passages? You might have blocked circulation and the water boiling is what is keeping the pressure up. Are you running the engine at higher than normal transom heights? It could be experiencing water starvation and again the boiling water is what is showing pressure on the gauge

 

[Dukedog]

Re: 1984 Mercury V150 Outboard

Do you have a water pressure guage? If so, what does it read? New complete water pump or just impellar? OEM or aftermarket?