Alarm on Volvo engine

[FlyingDutchman]

Our boat has the Volvo MD22A engine with the 'deluxe' instrument panel (with tacho, temp, oil pressure and volts meters on it.
If I switch on the ignition, the alarm sounds for something like 0.5 seconds and seem to fade out (pieu sound). I never payd attention to this, especially as the alarm sound on pressing the test button.
A few weeks ago, switching on the ignition, the alarm sounded longer, maybe 2 seconds, the faded away (piiiieu sound).
Should the alarm sound until the oil pressure has built up and the alternator is working after starting?
If so, what could be the cause of this effect?

Any comments highly appreciated!

 

[Talulah]

Alarm should sound until Alternator is charging. If the alarm is taking longer to stop sounding then it suggests the alternator is taking longer to output the charging voltage. The cause is usually either loose belts or the carbon brushes in the alternator becoming warn out. There are other possible causes such as poor connections. There is no immediate rush to panic. Check the belts. Tighten/replace if applicable. Do you have a battery monitor and can look at what output the alternator is sending? If it is the bushes then there should be no rush to replace. You have likely got some time yet before it stops charging all together. When the alarm sounds continuusly and can only be stopped by more revs than that is the time to replace the alternator brushes.

 

[FlyingDutchman]

Thanks Talulah,
the alarm stops before I start the engine!

 

[IKARUS]

Hi,
I've also a MD22A in my boat and I can tell you that my engine shows the same phenomenon. Don't worry about it - everything seams to be ok. /forums/images/graemlins/smirk.gif

 

[FlyingDutchman]

Many thanks Ikarus
and welcome to the forum!

 

[Landale]

Know the problem, it's a bad earth on the wiring loom connectors, in my case at the panel end rather than engine end, as by pushing all the connectors there I can get rid of it. - coincidently it can coincide with the rev counter refusing to work as well.

 

[FlyingDutchman]

Thanks Landale,
I will check that out.
The rev counter works ok though...