6bt alternator diode getting hot

[Bill]

hi guys
in trouble shooting a few things around my 6bt trying to trouble shoot my engine buzzer not working – i found that the diode that is on a yellow wire running to the alternator was getting warm when the ignition was on (engine not running) – i cut it out and joined the wires (engine still not running) and the voltage went up on the dash…..
I checked the other engine and couldnt find a diode to the alternator?

1) is a diode necessary?
2) is it getting hot normal?

I did a search and found a few different responses but i cant help feel that this could be linked to my buzzer not working (which is brand new) i have checked all earths and am totally lost as to why it stopped working. I am located in Australia and getting tradesmen to work on boats since covid is like trying to get on a spaceX flight to space – expensive and limited seats! – one guy told me November to inspect….. (and its our winter atm)

cheers

Topic

[Clark Leighs]

Yes, a diode conducting current will heat up. To much heat and it will go PIFF.

I am going to guess that it is in the line to excite the alternator for instant charging start at engine startup. NO waiting for residual magnetism to build.

Some alternators need the diode to stop any back feed which can prevent the engine from shutting down when you want it to. That back feed MAY keep the fuel shutoff energized which will feed fuel thus preventing engine shutdown.

You might try the shutdown cycle to find out. Just be prepared to have an alternate means of stopping the engine. A switch in the yellow line could be used to test.

This is a GUESS.

[Author]

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