Generator voltage oscillation

[jmooney]

I have two 20 KW Kohler generators , one of them has just started to vary the voltage slightly, but enough to trigger the AC warning. Switching to the other generator stops the warning. The engine does not seem to change rpm , although I should check the rpm with a tachometer. The bushes have been replaced , although two are worn more than the others . The variable resistors have been replaced in the past and look good. Does anyone have any ideas before I have to hire a specialist ? My go to guy retired and the generator shop (Don Hillman) stopped servicing generators on boats . They still sell parts, but they said getting to the boats and having access to work on the generators in the boats was difficult.

[Pascal]

I would bet on the voltage regulator. Frequency is set by RPM but voltage is usually set by a regulator. Not sure about Kohlers though. Where are you? In Miami?

[jmooney]

Yes , in Miami. The variable resistors regulate voltage and I have replaced both. Wire connections to the resistors seems tight .

[Pascal]

Yes , in Miami. The variable resistors regulate voltage and I have replaced both. Wire connections to the resistors seems tight .

Try Alex at Precision Generators. Not sure if he works on Kohlers but he does Onans, Wstbk, NL. I ll pm the phone nr

[jmooney]

Thanks,Jim