Engine Alarm, Intermittent Buzzing

[canuck]

We have a 2004 #1678 with a M35B. We took out the boat yesterday for a couple of hours of motoring to calibrate new radar. On the way back I started to hear a very intermittent low volume buzzing sound from the alarm when at cruising speed, about 2600 rpm. The water temp and oil were fine. Engine ran great. Back at the dock I shut the motor down and got a good tone from the alarm before restarting and stopping. Seems everything is OK other than this new irritant. Has this happened to anyone else? Any suggestions?

[Roc]

I've had an intermittent 'chirp' coming from the buzzer when at certain RPM's (probably the vibration caused at a certain RPM).  This has been since the boat was new.  I figured when the buzzer goes, I'll put a new one in and maybe it will stop.  When I do hear it, I just very slightly change the RPM's and it goes away. It's always at about the same RPM's when it happens.  I just about know how to make it happen if I want.

[Bob Kuba]

I've had this happen before.
Turned out to be a loose wire connection at the oil pressure sending unit.
After cleaning up the connection, the chirping stopped.

[Stewartn]

Not sure it's the same thing, but....
On #1472, 2000 C34 MkII, got an intermittent engine alarm. Tried everything. Nothing worked to shut it up. Finally got a smart mechanic who figured out the alarm wires are are routed from the rear of the engine up and around the block to the senders. These wires, heat and oil alarms, don't have a lot of insulation from the factory and the heat alarm had chafed through and was grounding out, intermittently. We used some spiral insulating material from the top down and it seems to have cured the problem.
Called Westerbeke and asked about replacement wires...According to W, it needs a whole new harness. I asked about a 2nd class fix... W suggested just splicing the wires.
Hope it helps.
StewartN
C34 #1472
Desiree, OGYC