Alarm on 40 HP Merc

[Barnacle_Bill]

This is a 2003 40HP Merc Ser 0T754967. I don't have access to this motor but the problem has been isolated to the low oil alarm circuit. I know there has been talk about magnets coming loose in some of these but I'm a little confused. What triggers the switch in this one? Item 17. http://www.mercruiserparts.com/Show...=3021&bnbr=150&bdesc=Oil+Injection+Components

 

[Texasmark]

Re: Alarm on 40 HP Merc

I dug into my service manual for your answer. It's for mid range Mercs, but I bet it's teh same for the 40.

In the Low Oil Sensor Test Chart they have you make continuity tests on the blue "low oil sensor leads" with an ohmmeter.....on other year models the leads are light blue.

Depending upon how much oil is in the tank, if over half there is no continuity between the leads (to the sensor in the tank). If under, there is continuity....will be a short circuit.

If test fails they indicate that the magnet may have fallen off the bottom of the float......that is your trigger mechanism. If it fails, remove the sensor (follow the blue wires to it) and retrieve the float from the tank. I guess it's epoxied to the float; dunno, never took one apart.

HTH

Mark

 

[Barnacle_Bill]

Re: Alarm on 40 HP Merc

Thanks Mark. I'll have him see if he can find a loose magnet in the tank.