Yanmar YM oil pressure alarm failure

[ctlow]

The other day my oil pressure alarm failed. This is when starting and stopping the engine, the light should come on and the audible whistle activate.

I had this on a charter sailboat recently, too, and then it suddenly self-corrected.

Mine self-corrected too, by flipping the ignition switch from OFF to ON several times (engine not running!). It faltered at first, the light sputtering and the alarm sounding "dirty" and weak, and then suddenly they were both fine again.

I had been working around the engine and wondered if I had knocked a wire loose, but can't find one.

Is this something common or well-known, and easily user-serviceable?

I note that one can buy a replacement oil-pressure sensor, but don't know where it is on the engine itself, to even inspect it.

Thank you.

Charles

Yanmar 3YM20

[SVCarolena]

They way you describe it, it is most likely is a problem in the panel switch. I'd start there with a multimeter before going to the sender. Is is very uncommon for a sender to go bad, particularly on an interment basis like you describe. On the other hand, the panel and switch are exposed to the elements, so there could be corrosion inside.

[casey1999]

The wire harness have splice connectors- open them up and check for corrosion. Also some of these connectors at the panel. Spray with anti corrosion spray. Trace the wires from the panel to the oil pressure switch- the switch should be located around the oil filter- looks like a 1/2 pipe plug with a wire comming out the top. The water temp switch looks the same but located around the thermostat towards the top of the engine.

[JimsCAL]

If you remove the wire from the oil pressure switch and ground it, the alarm should sound (if the key is on). That would test the switch.

[ctlow]

All very helpful. Will investigate and hope to report back. Thanks to all.

[saillife]

Did you have any luck finding your problem? I too have an intermittent problem with the alarm. Mine seems to work once the engine is warm. I'm thinking it's the sender but, it could be heat improving a contact via expansion.

[ctlow]

Hello, saillife.

It simply started working again, and I have neglected to check into it. My bad. I had better have a look at the panel wiring - that alarm is a critical component.

Thanks for jogging my memory!

Charles

[ctlow]

The latest is that I jiggled everything I could find both on the engine block and on the back of the instrument panel, and nothing worked to restore the alarm.

The next day, however, and ever since, the alarm (and light) has worked. So if I take it in, it will all be working and they won't want to fiddle with it.

-sigh-

Where is the oil pressure sensor on the block, anyway? I can follow all sorts of wires - sort of - but can't convince myself which one is which and can't find a diagram of it. 3YM20.

Thank you.

Charles