'86 300 Weekender alarm (horn)

[joenofish]

I have an alarm (buzzer / horn) I don't have a clue what it's telling me... I have 40psi oil pressure on both engines, 140deg water both engines, no water in the bilge or AC condensate well, trannies are full, boat operates perfectly.

Does anyone have a suggestion? This is an '86,300 weekender with twin 260HP Mercruisers, well maintained and great shape.

I want to take a trip this holiday weekend however I can't leave the marina until I solve this mystery.

Thanks,

Joe in St. Pete, FL

 

[1956olds]

Does it buzz even after the engines are running?Could be a wire got bumped under the dash at the key switch,or a bad switch.Do you have fire suppresion system? is the system charged ?Mabey dirty oil sensor or wire to it has been knocked off.Try to follow the wires from the buzzer to see where they go.

 

[SCORPIO]

Could be that a temp or oil pressure switch is bad or disconnected. The alarm uses a seperate sender from the dash gages. Start by looking at all the wiring on the senders and see if anything is broken/loose/missing. Next I'd replace the aforementioned senders, that should stop the alarm.

 

[joenofish]

Does it buzz even after the engines are running?Could be a wire got bumped under the dash at the key switch,or a bad switch.Do you have fire suppresion system? is the system charged ?Mabey dirty oil sensor or wire to it has been knocked off.Try to follow the wires from the buzzer to see where they go.

It's the craziest problem, sitting in the slip, both engines at idle (at normal temp), the buzzer sounds randomly (on and off), when it sounds when we are up on plane, it stays on steady (most of the time). The buzzer sounds steady with the engines are off and the ignition is on (no oil pressure).

I don't know if the switches that are in this loop are normally open or normally closed, I asume oil pressure from the engine and trans closes a normally open contact, that makes me think a failing switch would trigger and alarm (open circuit - alarm sounds?)

I may take Scorpio's advice and swap the three sening units on each engine / trans.

I believe my engines are perfect, I do not know if one of the trannies are about to have a costly problem..

Thanks,

Joe

 

[twomad]

check the sensors on the tranny right on top easy to see and easy to disconnect or break off

 

[Saverio]

I had a boat where my depth finder was tyied in with the alarm buzzer.