Question about water temp alarm

[numlock]

I have a '93 Hunter 30, Yanmar 2GM20 engine. When I first turn the key to start the engine the alarm buzzer does not sound. However when I shut the engine off by pulling the kill switch before I turn off the key the buzzer usually does sound.

I have assumed that the alarm is working properly but maybe this is not correct. I assumed that the point of having the alarm sound when first turning the key before starting the engine is to ensure that the alarm is working. If it sounds when I shut the engine off, then it must have been working. Right? But why wouldn't it sound when I first turn the key before I start the engine like it is supposed to?

Any ideas or suggestions would be appreciated.

Numlock
Sackets Harbor

 

[Shell]

Sounds like something is not wired correctly.

 

[Bill Roosa]

Buzzer basics

The buzzer may indicate any/all of the following:
low charging voltage if hooked to the alternator
low engine oil pressure if hooked to an oil pressure switch not a pressure sensor
high engine coolant temp if hooked to a water tem switch not a temp sensor
one buzzer 3 functions

The buzzer should come on before engine start due to the low oil pressure condition and the not charging condition. The buzzer does not come on as a systems check before you start the engine. It should come on a few moments after engine stop for the same reasons. If it comes on immediately upon the engine stop it is probably not the oil pressure switch turning it on but the low alternator voltage. I can tell a change in tone as the oil pressure drops and the buzzer circuit sees less resistance from both the alternator and low oil pressure circuits.

Since you do not get a buzzer before engine start but do get on after engine stop I would surmise that the alternator and oil pressure circuits are either disconnected, not present or hooked to a sensor instead of a switch.

Check the number of wires grounding the buzzer. The ignition power supplies 12+ and each circuit can ground the buzzer. You may not have all the circuits described above so you will have to do some recon to determine which ones you have.
The circuits must be grounded through a switch and not a sensor (variable resistor) to work properly. The alternator circuit will be controlled by the regulator which could possibly be inside the alternator.

 

[petersea]

Remember the alarm is for both water temp and oil pressure. Yes it should sound with just the key on not running. Check both sending units as well. What about the indicator ligths on the instrument panel do they light up and go off correctly ?

 

[numlock]

Thanks for the info

The buzzer may indicate any/all of the following:
low charging voltage if hooked to the alternator
low engine oil pressure if hooked to an oil pressure switch not a pressure sensor
high engine coolant temp if hooked to a water tem switch not a temp sensor
one buzzer 3 functions

The buzzer should come on before engine start due to the low oil pressure condition and the not charging condition. The buzzer does not come on as a systems check before you start the engine. It should come on a few moments after engine stop for the same reasons. If it comes on immediately upon the engine stop it is probably not the oil pressure switch turning it on but the low alternator voltage. I can tell a change in tone as the oil pressure drops and the buzzer circuit sees less resistance from both the alternator and low oil pressure circuits.

Since you do not get a buzzer before engine start but do get on after engine stop I would surmise that the alternator and oil pressure circuits are either disconnected, not present or hooked to a sensor instead of a switch.

Check the number of wires grounding the buzzer. The ignition power supplies 12+ and each circuit can ground the buzzer. You may not have all the circuits described above so you will have to do some recon to determine which ones you have.
The circuits must be grounded through a switch and not a sensor (variable resistor) to work properly. The alternator circuit will be controlled by the regulator which could possibly be inside the alternator.

Looks like I'm going to have to role my sleeves up for this one. Darn. I was hoping for an easy fix.

My main worry is that the alarm won't go off when the water filter is clogged (happens sometimes) and the engine will overheat and cause damage without my knowing it and stopping the engine to clear the filter in time.

Cheers,

Numlock
Sackets Harbor, NY
Wind Dancer
'93 Hunter 30T

 

[kloudie1]

Something to think about.. as buzzers fail, they will begin to not work when cold especially if there is some condensate in it from dew or rain.. after the panel warms up from use, it will mostly work.. Mine sort of "gurgles and wheezes" sometimes when cold.. I expect it will die before many more years. If the lights are working, the buzzer should be on.

 

[numlock]

I blush to admit...

Remember the alarm is for both water temp and oil pressure. Yes it should sound with just the key on not running. Check both sending units as well. What about the indicator ligths on the instrument panel do they light up and go off correctly ?

...that I don't know whether the lights are lighting. I haven't looked at the lights, I think ever. I've owned the boat since 1997 and used it a lot.

According to the manual which I have finally looked at the water temp light does not light on ignition.

I'm going to run this down before I start the engine again. I promise.

Cheers,
Numlock
Sackets Harbor, NY
Wind Dancer
'93 Hunter 30T

 

[Bill Roosa]

Common problems

If you can find the coolant overheat switch and oil pressures switches check the following:
does the switch body have a circuit to ground? They typically use the engine as a ground so if the fittings (threads) are corroded you can get various results as the engine heats up.
Are the wires at the switches showing 12 volts with the engine ignition switch on? The circuit supplies 12+ to the buzzer then runs through the appropriate indicator light and then to the switch so there should be 12 volts at the switch.

 

[navigator97]

Nunlock,

If I may, I'd like to venture a guess that one or more of the "fast-on" connectors on a wire have "relaxed" and need to be re-tightened - squeeze gently witha a needlenose pliers (after you check to see if one or more are loose). These will be at the pressure and temp switches and behind the engine control panel.

Dick, S/V Puffin

 

[Steve C.]

The water temp sender is not grounded unless the engine is hot. You can turn the key on ground the wire and the light will light, if not there is another problem.

 

[Numlock]

I'll try that

Nunlock,

If I may, I'd like to venture a guess that one or more of the "fast-on" connectors on a wire have "relaxed" and need to be re-tightened - squeeze gently witha a needlenose pliers (after you check to see if one or more are loose). These will be at the pressure and temp switches and behind the engine control panel.

Dick, S/V Puffin

Thanks. I'll try that. I have a feeling that's the problem. I grounded the water temp alarm with the engine on and off and the alarm sounded, so I think that is ok.

 

[Allan12210]

Re: I'll try that

Mine was like that too. It turned out that the oil pressure sender was indeed bad. It became temperature dependent. When cold...nothing. When hot, worked fine. Replaced and it worked hot or cold. Don't use teflon tape on the threads...it can't ground and then it won't work anyway.

 

[Sailgunner]

Looks like I'm going to have to role my sleeves up for this one. Darn. I was hoping for an easy fix.

My main worry is that the alarm won't go off when the water filter is clogged (happens sometimes) and the engine will overheat and cause damage without my knowing it and stopping the engine to clear the filter in time.

Cheers,

Numlock
Sackets Harbor, NY
Wind Dancer
'93 Hunter 30T

You should install a temp gage. I did and that is a great addition.