Overheating generator? Wax splatter

9

99sh

Member
On to the next! My ammeter was showing 0A when driving which turned out to be a broken 3rd brush. I replaced that and getting a solid 10A now driving with no lights. I did set my 3rd brush to the very top given I'm running LEDs and no real load.

After my first drive I noticed some red wax splatter on my engine cover. The guts of my generator did have red wax in some locations (I honestly dont remember where now. Not the armature but in the outer housing). From what I've read this is indicative of overheating? I did also install a new diode cutoff at the same time.

I'm inclined maybe to leave it alone and see if it splatters again.
 

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the third brush is broken,the wires to the brushes looks like regular primary wire instead of the high strand count original wire— it’s stiff and could easily prevent proper bush movement.
it doesn’t look like the “wax” or whatever was important for operation.
 
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The wax is part of the insulating material in the field windings. Most likely there is a poor ground somewhere in the generator assembly. this could be a simple as too much paint where the mounting brackets meet the engine (either on the brackets or on the boss on the timing cover). It can also be caused by poor grounds between the front and rear generator covers and the case, between the pole shoes and the case, between the ground connection from the windings to the case (internal from the winding on the engine side of the case, or all of the above. When grounding is poor (not non existent, the electrical system goes "searching" for better ground. This causes the overheating scenario and allows the wax to discharge from the insulation. If left unchecked, it can ruin the windings and/or the armature. If your generator is currently working properly, I'd probably still take it off the engine and check contact at the mounting surfaces.

A similar situation occurs when somebody tries to start a "barn find" automobile that has been left to the elements (even inside storage) for long periods of time. It's not uncommon, in these instances for even the steel gas lines to heat up.
 
Are you saying you are getting a solid 10 amp charge with the third brush set all the way to the top? That ain't right.
 
Checked grounds between housing to chassis and got 0-0.1 ohms.

I took off the cover to verify my brush position. It wasnt all the way up, maybe 3/4" down. Moved that to the very upmost position. Maybe that was it?
 

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99sh said:
Checked grounds between housing to chassis and got 0-0.1 ohms.

I took off the cover to verify my brush position. It wasnt all the way up, maybe 3/4" down. Moved that to the very upmost position. Maybe that was it?
Click to expand...
Yes! Fried it!
 
I recently installed a newly rebuilt generator purchased from a Model A parts supplier and noticed wax on the engine pan as 99SH did. When I installed the generator it was charging 10amps at idle. My lights are all led and I have a solid state voltage regulator. I adjusted the 3rd brush and was able to lower the ammeter output to 0. Based on the above information I will have to check for any ground resistance within the generator and the mount.
Thanks 99SH for the post.
 
The red wax is a coating applied to the new made field coils. I restore a lot of generators and see this often. After some use, the excess wax melts off and drips out. It is disturbing to see, but harmless. Before installation, I've started to place new fields in a 150 degree oven on paper towels for about 20 min to melt off the excess wax. This all but eliminates the issue.
Steve
 
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