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John White
John White, Marine Mechanic
Category: Boat
Satisfied Customers: 306
Experience:  11 years experience working on outboards, inboards, sterndrives & pwcs
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We have twin 2002 Mercury Optimaxs. The oil sensor on the Starboard

Resolved Question:

We have twin 2002 Mercury Optimaxs. The oil sensor on the Starboard engine keeps going off but the oil resevoir indicates that the engine is getting oil. What should we look for?
Richard Goethel / Captain Kurt Goethel [email protected] [email protected]
Submitted: 7 years ago.
Category: Boat
Expert:  John White replied 7 years ago.

Are you receiving a low oil or no oil warning? Low oil would be 4 short beeps every 2 minutes from the alarm. No oil would be a continuous tone from the alarm and wide open throttle would be limited to 3,000 RPMs. If you can, provide the engine serial number. The picture below will show you where to find the serial number on the engine.



Customer: replied 7 years ago.

My Son, Kurt, says the engine gives 2 short beeps does nothing for 5 minutes or so and then does it again. He will call me back with the serial number and I will provide it to you. You can call me toll free at XXX-XXX-XXXX X 1340 or on my Miami cell phone at XXX-XXX-XXXX..


Expert:  John White replied 7 years ago.
We're not allowed to share contact information or contact you outside of the site. On the alarm just have him double check to make sure, I'm not showing an alarm that sounds 2 beeps every 5 minutes. If there's a smartcraft gauge installed let me know what it's showing.
Customer: replied 7 years ago.
Could it be that the oil sensor alarm is malfunctioning?
Customer: replied 7 years ago.

The serial number for the engine is OT554751


Customer: replied 7 years ago.
How can you tell by physical inspection of the engine that the oil is being sent from the resevior? Richard
Expert:  John White replied 7 years ago.

It could easily be the sensor or float in the oil tank bad. If this were the case you would be getting 4 beeps every 2 minutes, so have him check on that. The oil tank mounted on the engine should always be full. If it's low at all there's a problem in the delivery system between the main tank and it or the main tank is very low to empty.


The easiest way to test this situation is to bypass the oil tank sensor for now. There will be two blue wires coming out of the top of the oil tank that plug back into the engine wiring harness, disconnect both wires. On the two wires that go back to the engine wiring harness, use a piece of wire or paper clip to tie them together. If this eliminates the alarm then you know the problem is in the sensor or the float. Just let me know what you find and we can go on to figuring out the exact problem.

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Expert:  John White replied 7 years ago.
Testing the oil pump itself is a little more complicated, but if this were you're problem you would have a constant alarm and the engine wouldn't rev past 3,000 RPMs. An overheat condition would give you the same results with the alarm and RPMs. If it comes down to it I'll be happy to walk you through the procedure for testing the oil pump, but let's start by testing the easy stuff first.

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