The Ford Barn

jrhaelig · 09-07-2013, 04:57 PM

Went for a 12 or 15 mile drive today. Big doings for us so far....

I noticed that my generator now whirs. Even at idle it sounds "engaged".

Kind of like a power steering pump in normal operation.

With the ignition off I had 6.25 volts across the battery before I left and 6.33 after I returned. No lights or accessories were used.

Should a gennie be silent?

I thought they didn't function at all at low idle.

What do you think?

rotorwrench · 09-07-2013, 06:29 PM

There may be a bearing or brush problem. Generators normally run pretty quiet. Belt tension puts a fair load on the front bearing and the back bearing may be dry. They usually have a little oiler for the bushing.

Bluebell · 09-07-2013, 08:42 PM

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If it has a bush at the rear, and you oil it, only use a small amount of oil. You don't want any oil getting to the brushes.
Usually the bush is an "oilite" bush. One that is saturated and holds oil, made of sintered bronze(little balls squashed together.
The bush can wear out on one side, usually from the belt being too tight. The load on the pulley cantilevers on the ball bearing at the front, and cuts out the bush at the back. When the bush is badly worn (or the bearing fails in the front, the armature can start to rub on the pole shoes. This is called "poling" and leads to the destruction of the armature. This could be a cause of the noise.
Generators can be noisey because of the brushes. The commutator where the brushes run on the armature has mica (an insulator) between the segments of copper. The mica is supposed to be "undercut" in other words, below the surface of the copper.
If the copper has worn down the carbon brushes start hitting the mica, and can cause a noise.
If the brushes are stuck, and don't move freely they will arc. This can also happen if they are worn out.
I should have given you the easy bit first, sorry.
I don't know specific details about your type of generator. This is general stuff.
Hope that helps.

09-07-2013, 04:57 PM	#1
jrhaelig Senior Member Join Date: Mar 2011 Location: Bridgewater, New Jersey Posts: 264	Generator Whir Went for a 12 or 15 mile drive today. Big doings for us so far.... I noticed that my generator now whirs. Even at idle it sounds "engaged". Kind of like a power steering pump in normal operation. With the ignition off I had 6.25 volts across the battery before I left and 6.33 after I returned. No lights or accessories were used. Should a gennie be silent? I thought they didn't function at all at low idle. What do you think? __________________ John Haelig Bridgewater, NJ 1939 Ford Pickup 1963 Lincoln Continental 1939 Buick

09-07-2013, 06:29 PM	#2
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,426	Re: Generator Whir There may be a bearing or brush problem. Generators normally run pretty quiet. Belt tension puts a fair load on the front bearing and the back bearing may be dry. They usually have a little oiler for the bushing.

09-07-2013, 08:42 PM	#3
Bluebell Senior Member Join Date: Nov 2012 Location: Tauranga, New Zealand Posts: 726	Re: Generator Whirr Sponsored Links (Register now to hide all advertisements) If it has a bush at the rear, and you oil it, only use a small amount of oil. You don't want any oil getting to the brushes. Usually the bush is an "oilite" bush. One that is saturated and holds oil, made of sintered bronze(little balls squashed together. The bush can wear out on one side, usually from the belt being too tight. The load on the pulley cantilevers on the ball bearing at the front, and cuts out the bush at the back. When the bush is badly worn (or the bearing fails in the front, the armature can start to rub on the pole shoes. This is called "poling" and leads to the destruction of the armature. This could be a cause of the noise. Generators can be noisey because of the brushes. The commutator where the brushes run on the armature has mica (an insulator) between the segments of copper. The mica is supposed to be "undercut" in other words, below the surface of the copper. If the copper has worn down the carbon brushes start hitting the mica, and can cause a noise. If the brushes are stuck, and don't move freely they will arc. This can also happen if they are worn out. I should have given you the easy bit first, sorry. I don't know specific details about your type of generator. This is general stuff. Hope that helps.