Ignition warning buzzer -4600scb

[sandiegoguy]

Had the boat out this weekend and going around 2300 rpms, engines at the correct temps, correct oil pressure, 13 volts, port and starboard gauges had the same readings.

Then the starboard side started buzzing at the warning light next to the ignition switch. I slowed down and stared at the gauges trying to find what happened and nothing unusual. Then buzzing stopped (light went off) after about 40 seconds and didn't do it again. By that time I was at the marina going just 800 rpms. Boat ran great, gauge readings were solid.

is this buzzer for low oil pressure?
Is it possible its fuel related? That is the one thing I havent done to the boat (clean/replace recors)

[mmwjr]

Diesels? Sounds like a faulty warning switch but not knowing you engines I cannot say.

[sandiegoguy]

Originally Posted by mmwjr

Diesels? Sounds like a faulty warning switch but not knowing you engines I cannot say.

Yes diesels (370hp)
just wondering if dirty or fuel with water could trigger it also.

[dbriceno]

The buzzer signals low oil pressure. If the gauges looked fine maybe there is a separate sending unit for the buzzer. You should have a Cummins mechanic take a look at it.

[sandiegoguy]

Originally Posted by dbriceno

The buzzer signals low oil pressure. If the gauges looked fine maybe there is a separate sending unit for the buzzer. You should have a Cummins mechanic take a look at it.

Are you suggesting a bad sending unit causing a false "buzz" or a bigger problem?

[mmwjr]

Warning systems use a separate sensor than the gauges. Have it checked out as I have a friend who thought his was a bad alarm sensor and it turns out the gauge sensor was bad giving a false ok, cost him an engine.

[sandiegoguy]

I'll look into it but I'm pretty sure it's not the gauge as it shows the current oil pressure, not just a light. At idle the oil pressure is lower, at 2500 rpms its 40, etc. and it matches the port side gauge exactly at all rpms.

But I will check it out regardless, thank you!

[mmwjr]

Originally Posted by sandiegoguy

I'll look into it but I'm pretty sure it's not the gauge as it shows the current oil pressure, not just a light. At idle the oil pressure is lower, at 2500 rpms its 40, etc. and it matches the port side gauge exactly at all rpms.

But I will check it out regardless, thank you!

Understood and that is what my friend also saw, turns out the faulty sender showed the same OP as the other engine however a mechanical gauge used to test showed it was wrong unfortunately it was too late and the bearings were done for.

[sandiegoguy]

Originally Posted by mmwjr

Understood and that is what my friend also saw, turns out the faulty sender showed the same OP as the other engine however a mechanical gauge used to test showed it was wrong unfortunately it was too late and the bearings were done for.

wow, that would seem very unusual. The gauge reads exactly like the port side at all RPMs yet it is wrong?? hmm, ok I will get a mechanical gauge on there and check it out.

Thanks for the info!

[mmwjr]

Yes very strange indeed, that's boats for you.

[sandiegoguy]

I was told clean all connections first. Spray with WD40. Then switch the senders (port and starboard) and see if the opposite engine starts buzzing. Seemed like a good idea.

[mmwjr]

Originally Posted by sandiegoguy

I was told clean all connections first. Spray with WD40. Then switch the senders (port and starboard) and see if the opposite engine starts buzzing. Seemed like a good idea.

Agree, including the alarm sender. There is risk in damaging the senders doing so.

[TJK]

For the C series engine., the buzzer is for low oil pressure and/or hi temp. I believe your B series engine should be simlilar.

[sandiegoguy]

Originally Posted by TJK

For the C series engine., the buzzer is for low oil pressure and/or hi temp. I believe your B series engine should be simlilar.

ok, i will do some investigating and see how many wires are ran from the buzzer, etc. so I know if its just oil or more.

thanks everyone!

[TJK]

Possible scenario:

!. Cooling water intake was clogged by debris (plastic bags, sea weed, etc) temporarily.

2. The water temp gradually went up, then you got the hi temp warning.

3. As you slowed down, whatever stuck on the intake drifted off as the suction of engine intake was reduced, as well as the boat speed came down; therefore, the water flow under the hull was reduced to have the debris detached from hull/intake.

Again, it's just one of many possible scenarios.

[sandiegoguy]

I checked the engine temp gauges right when it happened. Looked at oil pressure, temp and even RPMs to see if something was off compared to the port engine but it was all identical.

temp was about 175-180
oil pressure about 40
2200-2300 rpm

so I'm leaning towards a connection issue or sender but I'll try and locate it...hopefully.

[sandiegoguy]

I've attached a file that shows my buzzer and what I think is the oil sending unit on the engine. My buzzer has a lot of wires coming off of it so I don't think it's just for oil. At mininum, oil and temp.

See the right side picture where i put "whats this"
Any idea what this connection is?

[mmwjr]

Not certain but I think it's the oil pressure switch for the alarm.

[sandiegoguy]

ok, one is for the gauge and one is for the buzzer I take it?

[mmwjr]

Originally Posted by sandiegoguy

ok, one is for the gauge and one is for the buzzer I take it?

Correct