2010 Merc 150 Optimax, oil supply question

[JackOLMI]

2010 Merc 150 Optimax. I encountered the standard 4-beep warning while slowly getting on plane. Main oil tank was about 1/3 full. Filled tank to 3/4 full. Then opened engine mounted oil tank cap and found the oil a little low (1/2 inch low, some air). Started engine and purged air from engine mounted tank, then sealed cap and assured no leak. Still have 4-beeps after 2 ignition cycles. Any suggestions for next steps ? Everything else looks fine.

 

[ajgraz]

Very possibly a failed oil level sensor in the oil tank. From what I've been reading, this has been a well-known problem on Mercury's for some 30 years now. My 2014 OptiMax 125 has the same issue.

It is my understanding that on certain "older" motors, the sensor itself is replaceable...or at least repairable through the tank opening. But that on "newer" units, the only fix is a whole new tank/sensor. Not sure exactly what models/years, but I do know mine is not the repairable/replaceable kind. Not ready to shell out $300-$400 for a new tank with a sensor that is very likely to fail again, and definitely not taking a chance on a used one.

I've heard you can "spoof" it by disconnecting the sensor and jumpering the harness. I've also heard that you want to disconnect and NOT jumper. I've also heard you want to disconnect only one wire. Naturally, all threads I've found on various forums where these fixes have been suggested have no "follow up" that say "this worked" or "this didn't work." Of course, if you spoof the sensor, you'll have to get in the habit of visually making sure your oil tank is filled--which IMO you should do anyway.

I haven't tried any of these fixes myself yet, but I'm going to. After I replace the buzzer itself, which has also failed to where I have to stick my head inside the center console to hear it.

 

[stikboyy]

4 beeps is either a low oil level/oil sensor issue or water in the fuel. You can check the sensor in your oil tank by unplugging the 2 wires that come from the sensor and hooking up an ohm meter. If the oil tank is full the sensor should have no continuity - if it has continuity and the tank is full; then you need a new sensor.
To check for water in your fuel just pull off the water separating fuel filter located on the engine (on your engine i believe it has a red top and is threaded into the (VST)vapor separating tank on the port side of your motor. and check for water in the VST.

 

[JackOLMI]

Thanks for the feedback. My sensor is serviceable. I unplugged the wiring harness, checked for continuity, and had none (oil tank was full). I removed the sensor, wiped it down, and checked for continuity, and had none. I ran a magnet along the sensor and still had no continuity. At this point, since the sensor never changed states, I assume it is bad ?