2005 Mercury 150hp Optimax - low oil warning alarm

[Bassinkorea]

This is a thread just for information that may help someone in the future.

So, I was running down the lake a few weeks ago on the morning of a tournament and started getting an alarm. My MercMonitor mentioned that "Oil Remaining - 99%" This percentage number was dropping steadily as I ran the motor. I quickly stopped running the motor. Totally ruined my day and tournament.
I had plenty of oil in my larger remote tank. I removed the cap from the small motor mounted tank and oil came out, meaning it was full. Totally baffled and not wanting to damage my motor, I just fished with the TM for the rest of the day.

Anyway, I took it to the shop on Monday morning. He switched the oil sensor and still alarming. He then switched the small motor mounted oil tank with a used one he had on another motor, and ran the motor. No alarm, woohoo!!

A new tank over here would cost me $200+, but the used one cost me $100 including labor. I've the boat out twice since, and no issues so far.

[Bassinkorea]

Here's a shot of the MercMonitor alarm.



Sent from my LM-V510N using Tapatalk

[Oldfart9999]

Electronics are nice until they don't work. Same thing with tire pressure monitors, the car pulling up next to you at a light can screw your's up and you need to buy new ones. Ahhh the brave new world.

[Deadeye]

Had the same thing happen on my 2004 150 Opti.

It is a Common Issue. The Sensor drops (smaller tanks on smaller engines use a chain to hold the sensor and the chain breaks- sensor thinks the oil ran out) and the sensor thinks the oil has been run out, so it sends the signal.

Cheaper and easier to swap out the small motor tank than to try a replace the sensor.

BTW, Since your tank was used expect the same thing to happen at some point.

[apenland01]

Yep, this happened on my 2004 optimax 225, very common issue.  That magnet separates from the float and off goes the alarms.....

The shop put on a new tank for me and all good.