1984 150 hp Johnson low oil or over heat buzzer

[johnchop]

I have a 150 hp Johnson that after it runs for about 3 or 4 min in the lake the low oil or over heat buzzer goes off but if I run it with the water ears on the buzzer won't go on. The oil tank is full and the VRO is pumping oil to the engine as there is oil smoke coming from the exhaust
and the water coming out of the engine is not very hot so I don't believe it is over heating, could anyone tell me what might make the warning buzzer go off?

 

[spencer591]

Best way to fix the problem is by testing all the alarm components. First run the motor in the lake till you hear the horn go on. Then take the temp sensors out of the circuit. If that fixes it you have a bad temp sensor or your motor is over heating. If that doesn't make it go off take the other alarm senders out until you find out what is part of the alarm system has failed.