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BJ-8 Generator Smoke

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fwtexasbj8

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All, think I have fried my rebuilt generator something bad! The original issue I was seeing was a fluctuation on my volt meter from an overcharge to an undercharge condition. I swapped regulators and saw the same behavior so took my generator and regulator to a local generator shop that has consistently done good work for me and others.

Diagnosis was a bad regulator so I got a new Moss unit. Once a good regulator was available, they discovered the generator was also bad so it was completely rebuilt and bench run/adjusted with the new regulator. I re-installed everything and all was good with a fairly constant 13+ volt output on the gauge during a quick 15 minute drive. I got home, shut everything off and started to get everything ready to wash her then began to smell a strong electrical smell. I opened the bonnet and smoke was pouring from both ends of my rebuilt generator! I quickly disconnected the leads and began to try to measure any unusual voltages to the field or output and with the key off, no voltage was measured. With the key on, I saw 2.3 volts on both the field and output wires. I started her to get back to my garage and only saw battery voltage so no generator output.

Any ideas what could cause this type of failure? All of the other wiring seems fine with no ground or short issues found.
 
Definitely sounds like a short and at this point there are so many variables to determine the cause of your short. Sounds to me like wires or connections got crossed somehow and maybe water became a culprit based on what your are saying. Anything is possible from my standpoint from the battery onward (or generator backwards?). Electrical know how has never been my favorite so hopefully many others will get into this and help you out. Good luck.
 
This may help.......
10649664_10203654237931123_7194034203093247299_n.jpg
:encouragement:
 
fwtexasbj8 said:
All, think I have fried my rebuilt generator something bad! The original issue I was seeing was a fluctuation on my volt meter from an overcharge to an undercharge condition. I swapped regulators and saw the same behavior so took my generator and regulator to a local generator shop that has consistently done good work for me and others.

Diagnosis was a bad regulator so I got a new Moss unit. Once a good regulator was available, they discovered the generator was also bad so it was completely rebuilt and bench run/adjusted with the new regulator. I re-installed everything and all was good with a fairly constant 13+ volt output on the gauge during a quick 15 minute drive. I got home, shut everything off and started to get everything ready to wash her then began to smell a strong electrical smell. I opened the bonnet and smoke was pouring from both ends of my rebuilt generator! I quickly disconnected the leads and began to try to measure any unusual voltages to the field or output and with the key off, no voltage was measured. With the key on, I saw 2.3 volts on both the field and output wires. I started her to get back to my garage and only saw battery voltage so no generator output.

Any ideas what could cause this type of failure? All of the other wiring seems fine with no ground or short issues found.
Click to expand...
Did you flash the field when you hooked everything back up before starting the engine?
 
I did not flash the field as I assumed, maybe a bad assumption, that the generator shop had as the new regulator/generator combo had been set on his bench.
 
PTBJ said:
This may help.......
10649664_10203654237931123_7194034203093247299_n.jpg
:encouragement:
Click to expand...
You need the special order now obsolete smoke installation pump to be able to use this . I have one in my garage that I rent out for 999.99$ a day .
 
Now, this is more generic than specific, but if it ran fine, charged fine...and the issue happened when you got home and shut down, noticed as you were getting out of the car....bets are your ammeter was pegged to discharge..the Cutout Relay (in the regulator) stuck or defective.
Supposed to open when you shut down.
Don't think flashing for polarity would cause that...and that's 50 years of 6V positive ground generator system experience.
Pop the top off the regulator, see if any contacts are stuck together.
With the main wire off the generator, you should be able to power up and test.
 
The final diagnosis was a bad voltage regulator. Even though it was brand new, one of the coils had a pit in the contact and stuck closed which fed battery voltage back into the field essentially making it a heater. The generator was not fried, however it was over heated and the armature and brushes scorched a little. Polished the scorches and with a new regulator, all seems well again and she is back on the road.
 
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