Tachometer/rev counter malfuntion? Bavaria Ocean, MD22L Volvo

[Jam]

Hi
Have an issue with rev counter.  Will be working fine then often after a few hours the rev counter need drops, alarm bleeps  then needle returns to normal position .  The engine revs do not change during and engine running well?  Have had a look at rear of alternator and all is fine.   Alternator was recently serviced at start of season due to seized bearings

Any ideas appreciated

John

[dawntreader]

If everything appears normal then it may be a 'false alarm'. I had an engine 'false alarm' issue some time ago. I found a severely corroded block connector (see attached) which is part of the alarm circuit. I cut it out and used bullet connectors instead. Haven't had a 'false' alarm since.

[Jam]

 Iam sure it is a false alarm, as engine revs do not change.  Not sure why the rev counter needle drops, this is the fault that causes the alarm to bleep.  I found a similar forum trail on PBO forum but unfortunately no solulution.  Can motor 1hour or more then alarm sounds off and on erratically as needle drops......really irritating!!