Chirping alarm from Yanmar panel

[Sonosailor]

2GM20 with B2type instrument panel. Wired for overheating, oil pressure, and alternator output alarms. Three trouble lights, but one common buzzer. Buzzer is chirping after five minutes of run time, with no lights on or blinking, above 1800 rpm, in relative speed to the rpms. Belts ok, exhaust and water ok, contacts appear fine and are buffed and with dielectric, alternator output fine.

Suggested causes? In northern Martinique and "don't wanna stop the Carnival"!

[sailorchic34]

First verify the lights light up. My first guess is the temp sensor is going bad or the engine really is over heating and the high temp light is not working.

Do you have oil and or temperature gauges?

The buzzer is only connected to the lo oil pressure switch and the high temp. It is not connected to the alternator charge indicator. Could also be a bad buzzer too.

A bad t-stat would cause overheating too

[boatbod]

Look for water damage to the wiring harness plugs just under the exhaust elbow. Most small Yanmar engine harnesses have wiring for a sail drive water sensor. If the wires get shorted (wet or dirty plugs) the buzzer can sound intermittently.

[alctel]

My 2QM20 does this if I run it at low speed for a while - apparently it's caused by corrosion on the wire harness behind the panel/at the engine side. Probably the same reason my start button only works 3/4 times O_o

I am going to change all the wire out this summer. I'd recommend trying that (or at least the those bloody multiplugs), as I think the 2QM20 and 2GM20 have the same wire harness/panel.

[a64pilot]

Mine did that once, soon after the oil filter adapter O-ring blew.
I'd verify oil pressure is good, it just might be working correctly as mine was

[bill good]

If this problem is not related to any thing you have done lately you can compare the temp of each engine 10 mins after shut down by "feel" at the temp sensor for any difference. The over temp warning is more likely to activate indicating more investigation needed. (You may see this fault showing up on the bulb at night in the dark & not during daylight & that would be worth a look before getting too involved) RPM related -check that boot wire is a good idea. The test switch on the panel only tests the bulb & not the complete circuit. Fresh or sea water cooled?

At least you can limit the use of the suspect engine & still keep going when you have two engines!!

Regards

[Sonosailor]

Thanks for the responses so far.

You are right that there is a saildrive boot sensor - and it appears to be working correctly in a glass of water. Clean of material and no easy way to test for an intermittent short (or is there?)

You are right that the alternator or "exciting circuit" is not connected to the buzzer.

The panel bulbs are working properly, but certainly were not on during the events.

I have checked the wiring behind the pane and at the engine, and all looks good. I'll have to see if my disconnecting and reconnecting magically improved the situation.

I might go days before it recurs anyway, but will check the wiring connection at the other sensors.

[Drumroll30]

Originally Posted by boatbod

Look for water damage to the wiring harness plugs just under the exhaust elbow. Most small Yanmar engine harnesses have wiring for a sail drive water sensor. If the wires get shorted (wet or dirty plugs) the buzzer can sound intermittently.

This is exactly what happened to my boat several years back, the wire for the saildrive water was squished under a motor mount.

[jhulmer]

Originally Posted by Sonosailor

2GM20 with B2type instrument panel. Wired for overheating, oil pressure, and alternator output alarms. Three trouble lights, but one common buzzer. Buzzer is chirping after five minutes of run time, with no lights on or blinking, above 1800 rpm, in relative speed to the rpms. Belts ok, exhaust and water ok, contacts appear fine and are buffed and with dielectric, alternator output fine.

Suggested causes? In northern Martinique and "don't wanna stop the Carnival"!

a common problem with this engine or panel I guess.

My 2gm20 did this also, 1988 model. We tested all engine vitals, oil pressure, temp, raw water, fuel. But, all were okay.

It's a low volume chirp not a full on buzzer like when you turn the key on to start the engine. And we only noticed it at low RPMs but could have still been doing it at High RPMs but we couldn't hear it then.

We just got used to it I guess, couldn't find the problem. I sold the boat a couple years ago. We checked the connections but Never thought to check the wire harness. Might be related to high resistance as the harness ages.

[Cadence]

I'd guess it is oil pressure related. Start with the simple, replace your oil filter. Next would be the pressure sending unit. Based on the problem going away after 1800 RPM.

[bradandnatalie]

My 3hm35f did exactly the same thing. It turned out to be a faulty oil sender switch. You can simply check by removing the wire from the switch (on mine it's located just below the oil filter) and the alarm should stop altogether. The oil sender (pressure) switch is easy to replace and not too expensive. That chirping used to drive me nuts. Good luck.

[Paul L]

On my 4JH it was the water sensor built into the fuel filter. If you have one on this engine try unplugging it. It is just a small float and is sensitive to engine vibration.

[eroc]

A bit off topic, but the availability of the water in saildrive alarm is a neat feature which we connected to a raw water flow sensor on a shaft drive 3GM so now we get advanced warning of when raw water flow is lost or seriously restricted. The sensor is adjustable to flow and typically it will result in a chirp when rpm is low - reminds us it is still working. This without having to add an extra alarm.

[Lucky]

I had the same last year and it turned out to be the sensing wire termination on the generator, fixed the terminal and all was OK.

Happy lead free sailing from Lucky

[Sonosailor]

Chirping is gone. I intended to be scientific about it, changing only one variable at a time. I leaned over and unplugged saildrive sensor from the electrical harness. But then I noticed how accessible the neg bolt on the engine, with numerous connections was. I plugged the sensor back in, disconnected the engine negs, burnished and recoated with dielectric grease, and reassembled. Now I've messed with two things, but one of them worked.