westerbeke 4.5bcgb problem

[white glove]

I have a westerbeke 4.5 bcgb in my 2001 310 sundancer . The set starts fine but only registers 120 volts when a load is applied . prior to applying the load it hardly registers voltage at all. The set remains running through this but sometimes shuts down while a large load is applied.After warm up without a heavy load e.g. air conditioner and water heater the gen set hunts any will not provide a stedy 120 volts. any ideas on whats happening?

 

[wingless]

It sounds like the engine speed regulator is working fine.

The diodes within the diode rectifier pack should be individually measured for forward voltage conduction, about 0.6 VDC to 1.0 VDC and for reverse voltage resistance, open circuit.

Replace the pack is any fail the test. Use a DVM w/ a diode setting to measure.

My guess is the voltage regulator is bad. It feeds current into the excitor stator that energizes the excitor armature. The manual should describe the test for this component.

The testing would involve checking for DC voltage on the excitor stator and AC voltage on the diode pack w/ the engine running.

The excitor armature feeds the diode pack, then the main field rotor.

CAUTION - The voltages may be lethal and testing should be performed by qualified personnel.

CAUTION - Working on an operating engine should only be performed by qualified personnel.

 

[wingless]

The windings may be bad and those are easy to measure w/ an ohm meter. The winding should measure as low ohms, under 10, when tested w/ an ohm meter.

 

[white glove]

Thanks guys ,I checked with multimeter and found a bad capacitor .The new capacitor took care of it.