help with 300xs low oil level warning...

[motuman]

I have a (new to me) 2012 300xs with approx 110 hours on the clock. Serial #1E051504

Yesterday I had a experience a warning horn while cruising at mid-rpm. I opened my VesselView mobile app and saw the warning there as well, which said something like "engine mounted oil tank has critically low oil level".

I pulled the cowling and the oil tank appeared full, so I gently opened the bleed screw and oil oozed out (indicating tank was slightly pressurized). I removed the bleed screw and confirmed the oil tank was full to the top. I inspected the oil tank level sensor and wires and they appeared fine. I disconnected the oil sensor connector, ran the engine, and still experienced the warning horn. I then ran a small jumper wire between the terminals on the harness side of the oil level sensor connector. The warning went away, and the engine ran fine.

So I think I have isolated the problem to either a faulty oil level sensor or faulty float in the oil tank. I don't have a Merc tech nearby, so would like to repair myself if possible.

- The oil level sensor is inexpensive and easy to replace, but failure of a sold state sensor seems like the less likely at these low hours. Is there a way to test an oil level sensor? (without a merc scan tool)

- If the float is bad inside the oil tank is bad, is there a way to repair the float without replacing the entire oil tank? (assuming probably not, given small size of vent opening, etc)

- If I replace the engine oil tank myself, is there a reliable way to prime the tank without a Mercury scan tool? (if not, will make the drive to a dealer)

Thanks in advance.

[EuropeanAM]

Replace tank and sensor (both). Proper way to perform the oil pump prime is on the Computer Diagnostic System.