Isuzu marine control panel buzzer ......

[andybarrett1]

 

Hi 

 

Thank You for reading ....

 

We  have an Isuzu  marine control panel. 13 years old.   For the past few years , when in  idle  more after a decent run or load the buzzer sounds and is like an intermittent beep -like a uneven tick.   Also  when you turn on the key to start. Boat starts up ok BUT can just hear the buzzer very quiet in the background. Goes away after a few mins running. 

 

Just recently the buzzer sounded louder than the usual quiet on startup  and stayed on for longer than usual 30 secs or so ?

 

The alternaters recently replaced .... No magic sterling boxes involved.

 

I have checked all coonnections to be good . Both alternator belts nice and tight. Renewed just before lockdown.

 

Oil Presure dial has never worked ....

 

Any advice welcome 

 

 

Andy 

 

 

 

 

 

 

[Tony Brooks]

You do give the engine a little rev as it starts to ensure the alternator(s) energise?

 

If not then when its doing each it in turn pull off in turn and then replace the cable on the temperature switch and oil pressure switch. If one stops it then replace that switch/sender but I fear it won't. I suspect the alternator may have a problem.

[andybarrett1]

I thought it was the alternators ....So I replaced them .....Fault remained ?

 

Andy

[ditchcrawler]

I go for the oil pressure switch getting weak and alarming when the oil is hot at the lower  revs

[Tony Brooks]

26 minutes ago, andybarrett1 said:

I thought it was the alternators ....So I replaced them .....Fault remained ?

 

Andy

That is why I suggested either you may not rev the engine upon starting or you pull the cables of the oil pressure and engine temperature switches/senders before you consider the alternator. Note alternator singular because its unlikely to be both and you may well find one is not connected to a buzzer.

[andybarrett1]

7 minutes ago, Tony Brooks said:

That is why I suggested either you may not rev the engine upon starting or you pull the cables of the oil pressure and engine temperature switches/senders before you consider the alternator. Note alternator singular because its unlikely to be both and you may well find one is not connected to a buzzer.

Ah 

 

OK Thank you .... Yes I think it is the Engine Battery Alternator that goes to the buzzer .

 

Thank you 

 

 

 

 

[blackrose]

Mine buzzes on startup so I give it a rev and then the buzzer stops. I thought it was just an oil pressure warning that needed a rev to get some oil onto the sensor

[Tony Brooks]

3 minutes ago, blackrose said:

Mine buzzes on startup so I give it a rev and then the buzzer stops. I thought it was just an oil pressure warning that needed a rev to get some oil onto the sensor

 

More likely lack of alternator revs making it reluctant to energise. The clue will which warning lamp (charging or oil pressure) goes out in time with the buzzer.

[blackrose]

5 minutes ago, Tony Brooks said:

 

More likely lack of alternator revs making it reluctant to energise. The clue will which warning lamp (charging or oil pressure) goes out in time with the buzzer. 

 

Ok thanks,I never realised it was the alternator. Once I rev it the buzzer stops and then it can go back to idle without buzzing.

[Tony Brooks]

21 minutes ago, blackrose said:

 

Ok thanks,I never realised it was the alternator. Once I rev it the buzzer stops and then it can go back to idle without buzzing.

 

All unexceptional. It could be cured by fitting a more powerful warning lamp bulb or sticking a resistor across the warning lamp. I think Beta do the latter as standard.  Once the alternator produces enough voltage to open the field diodes those diodes powers the rotor rather than the weedy current from the warning lamp so even at idle there is plenty of current to keep the alternator energised.

 

Edited to add: If the symptom appears after an oil filter change then it could indicate that the filter you fitted has a faulty or no anti-drain back valve.

Edited June 4, 2021 by Tony Brooks

[Jen-in-Wellies]

16 hours ago, andybarrett1 said:

Ah 

 

OK Thank you .... Yes I think it is the Engine Battery Alternator that goes to the buzzer .

 

Thank you 

 

 

 

 

Another reason for it being the engine battery alternator that has the warning buzzer is that the drive belt for this alternator is also likely to be driving the engines water pump. If the belt breaks, then the water pump will stop, leading to engine overheating. Something you want to know about as soon as possibly. Another possibility for what you are hearing is a slipping drive belt. Is the belt tension OK? Belt worn? Bottoming out on the alternator pulley?

Jen

[rogerc]

i believe the 40A line fuse by the starter may have something to do with it

[andybarrett1]

29 minutes ago, rogerc said:

i believe the 40A line fuse by the starter may have something to do with it

Explain more please ?

 

 

 

[Tony Brooks]

30 minutes ago, andybarrett1 said:

Explain more please ?

 

 

 

 

I don't think he can because if that fuse blew or made bad contact it would be unlikely to start (no current to energise the ignition switch and starter solenoid). If it blew while the engine was running and the engine alternator was energised then the charge light would come on with the field diodes trying to feed the auxiliaries via the warning lamp, but once the engine was stopped it would not start.

[andybarrett1]

1 hour ago, Tony Brooks said:

 

I don't think he can because if that fuse blew or made bad contact it would be unlikely to start (no current to energise the ignition switch and starter solenoid). If it blew while the engine was running and the engine alternator was energised then the charge light would come on with the field diodes trying to feed the auxiliaries via the warning lamp, but once the engine was stopped it would not start.

Thats what I thought.... But open to possibilties !

 

 

[Tony Brooks]

3 minutes ago, andybarrett1 said:

Thats what I thought.... But open to possibilties !

 

 

 

So am I, every day is a school day. That fuse might cause the symptom if the domestic alternator is directly energised via the ignition switch rather than via a relay, but it would be the domestic warning lamp that illuminates.