1987 Mercury 80hp "Low Oil" or "Overheating" Alarm

[thormx11]

Took the pontoon out for the first time yesterday for the first fishing trip of the year. Boat ran great until the alarm under the dash started sounding. It was a contionous beeeeeep, not beep beep beep. Coming from something with "Delt-Larm" writtin on it right down from the ignition. I did a quick look online with my phone and from what I could find, the contionous alarm ment an overheating issue. But the motor was not hot, you could grab it with your hand, the lower unit was also not hot. We unhooked the alarm so it would stop sounding and we headed back to the truck.The boat still ran great, nothing seemed to be wrong. When we got home I did some more research on troubleshooting it and I found there are 2 blue wires coming from the bottom of the oil tank on the engine, I unplugged one and the alarm stopped.

Boat is a 1987 Bass Buggy, with matching 1987 Mercury 80hp oil injected engine.

Does anyone have any ideas what this could be? From my readings, I believe the "Low Oil" Sensor has gone bad, and it sets the alarm off.


BTW, when the alarm first sounded, the oil tank was a little over half full, When i got home I filled it the rest of the way up, and still the alarm came on.

 

[thormx11]

Re: 1987 Mercury 80hp "Low Oil" or "Overheating" Alarm

Anybody have any ideas? I'd like to know if it'll damage the motor if I keep using it or not.

 

[CharlieB]

Re: 1987 Mercury 80hp "Low Oil" or "Overheating" Alarm

Solid tone is an Over heat alarm, a rapid beeping is the oil alarm.

If it come on as the key is turned ON but leaving the motor OFF, LISTEN to be sure it is the rapid beeping of the oil alarm.

When disconnecting the low oil float switch cures it, the problem is an adhesive failure holding the magnet to the bottom of the oil leverl float. It fell off and landed onto or next to the magnet switch, setting off the alarm.

Since it is near impossible to remove and repair the float/magnet, you simply replace the tank assy.

 

[thormx11]

Re: 1987 Mercury 80hp "Low Oil" or "Overheating" Alarm

Solid tone is an Over heat alarm, a rapid beeping is the oil alarm.

If it come on as the key is turned ON but leaving the motor OFF, LISTEN to be sure it is the rapid beeping of the oil alarm.

When disconnecting the low oil float switch cures it, the problem is an adhesive failure holding the magnet to the bottom of the oil leverl float. It fell off and landed onto or next to the magnet switch, setting off the alarm.

Since it is near impossible to remove and repair the float/magnet, you simply replace the tank assy.

That's what I was thinking, but the alarm is. Solid and not beeping which is confusing me a little

 

[thormx11]

Re: 1987 Mercury 80hp "Low Oil" or "Overheating" Alarm

Today, just to check, I turned the key (not fired the boat) and the alarm has stopped. I have not ran the boat any since the weekend. The alarm stayed on (would come on when i turned the key) up until yesterday, If it was the overheating alarm, you would think that after 4 days sitting in the shop the motor would have cooled down and shut the alarm off,

 

[CharlieB]

Re: 1987 Mercury 80hp "Low Oil" or "Overheating" Alarm

Depending on the year and model, some motors did NOT have a rapid beeping oil alarm, the same solid tone was used for both overheat and low oil.

Either the float magnet came off or the module is going out.

First, did you reconnect the blue wires under the oil tank? If not, do it, turn the key ON, does the alarm sound now? If so order a new oil tank.

If not, still with the key ON, disconnect the tan wire to the temp sensor on the cyl head area and ground it. Does the alarm souond now? If so then the over heat is working correctly.

If the float magnet HAS come loose AND been dislodged, moved away from the magnetic sensor switch, the alarm would stop, HOWEVER, you will not have a functioning oil alarm and COULD suffer serious engine damage in the future if ever you fail to pay religious attention to the oil level.

It may be wise to remove the oil tank, drain it, and look to see if the magnet is laying in the bottom. Potentially saving yourself from a future engine rebuild.