odd engine / electrics problem

[wotayottie]

my boat has a volvo 2030 inboard diesel with a Sterling digital voltage regulator attached to the alternator. the engine ran fine on the 2 hour delivery from winter storage to my pontoon berth but as soon as the boat was in the lock and engine idling, an alarm started beeping. one beep about every 5 or 10 seconds but very regular.

when the engine was revved up the beeps stopped. they returned when I got to my berth and the engine was idling as I tied up but when I stopped the engine and re-started it maybe 10 mins later, no beeps.

now the alarm on the volvo instrument panels is wired such that it beeps for any of oil pressure, water temperature and charging whilst the warning lights indicate which one is the problem. no warning lights lit up ( and yes they are all working) and in any case the alarm is designed to beep continuously not at regular intervals. so I wondered if it could be a broken wire vibrating in and out of contact, but that would not beep regularly as happened. instead it would be intermittent. low oil pressure or overheating would trigger a continuous beep.

the boat has not been out since then but I have on two occasions run the engine for an hour or so tied to the pontoon. not a beep but then I didnt have the courage to run the engine at 2500 rpm whilst tied up ( only 1750 rpm) so the heat soak would not have been the same as on the initial trip.

any ideas? the volvo dealer is as stumped as me because all problems should give a continuous alarm not intermittent. and finally, the alarm itself works continuously as its designed to do if I turn on the engine electrics but dont start the engine so the alarm isnt faulty either.

 

[Stu Jackson]

When anything electrical is intermittent, it is 99% a connection problem. Either that or a faulty alarm board.

 

[wotayottie]

That was my first reaction Stu, but whilst I didnt get chance to time the beeps ( I was single handed) it was my impression that they were completely regular and if the engine vives are causing the beep by shaking a bad connection, the beeps would not be regular. And why would the problem not repeat?

 

[robertj]

possibly the engine was on the border line of having low oil pressure when idling, this would explain when motoring it was fine, but in the lock the idling maybe just on and off maintaining the pressure.
This could explain when you revved up it stopped and when on your berth it did the same idling, only stopping when you rested it and thus the oil cooled some what, allowing better oil pressure and the intermittent alarm stopping?
Has the oil been changed recently with the filter etc?

bob

 

[wotayottie]

yes it has robert, but the alarm wiring is such that if the oil pressure alarm triggered it has to light up the warning light as well as the sounder. and the warning light works OK.

 

[lw395]

I would suspect the Sterling regulator is causing this.
Is it a four stage smart regulator?
Does it suspend charging periodically to establish battery charge state?

I would rewire the alarm to only indicate oil and temperature. Those are the urgent things that need quick action to preserve the engine.

 

[safarovic]

Temperature

I would not re-wire the system as the charge control also gives information that the fan belt is not broken. A broken fan belt leads to very fast overheating. Do you know if the beeps came from the control panel or from somewhere else?
Good luck,
Horst