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Positve terminal on battery smoking when cranking

C

CMorris

Member
'50 8N sidemount distr. Still have not resolved the ability to get the engine to fire up. This morning i replaced all four brushes in the starter and now my positive terminal on battery is smoking and hot when i try to crank over the engine??
 
Better check the ground cable where it contacts the frame, or whatever. And, recheck the starter motor, too.
 
Have a careful feel of the negative terminal, too. If it's not excessively hot, check and clean the post and terminal on the positive (heck, ya might as well do both while you're at it, just to do things right) and, assuming positive ground, check the grounding end of the the positive cable and clean up that connection, too. What size cables?
 
The cables for both the pos and neg are standard copper core wires which are like original manufacture. I think that i may be getting this because the wire brush that i cleaned the termials off with had WD-40 on it. Thanks for your help.
 
The connection to the battery post is not clean and tight. It needs to be clean and tight or it will spit, spark, smoke and probably prevent starting.

Did you sand the brushes to fit the commutator? Did you turn the commutator? Did you replace the bushings to keep the armature from dragging on the pole pieces? If you didn't do all of these, you didn't finish the job.

Gerald J.
 
As battery cables get older they increase in resistance and that resistance in turn makes them get hot like your are doing. Sounds like you need new battery cables or you have some poor connections. If you have a 6 volt system you need BIG cables as in 00 or 0.
Hobby farm
 
Gerald,

Thanks for your response. I did not sand down the brushes since they already had a concave finish right from the box. I did spray them down with contact cleaner as well as the comutator. I"m not sure what you meant by the busshing which would keep the armature from dragging on the pole pieces? I am a fairly new tractor owner, I know very little about tractor repair other than what I can follow in the manual. Any further explanation you can provide is greatly appreciated.
 
Clean the battery post and cables with course emory cloth ,in rolls one inch wide is about right,until they shine nice and bright.Also the mounting ends of cables,with bolt holes.
 
Thanks for the recommendation. I do have some of the blue emory rols for plumbing that should work well.I think the brush that I used to clean the terminals earlier had some WD-40 on it.
 
All the rest is good advice, but check the battery itself too. Have had failures where the terminal itself was defective. More common on top terminal batteries, but have had side terminal failures too.
 
The bushings are in the end caps at each end of the armature. These center the armature in the case and keep it from rubbing the field poles. The poles are the windings that are bolted in place on the inside of the case of the starter. The armature is inserted thru the poles.
 
The bushings are the bearings for the armature. The magnetic forces on the armature pull it towards the field pole pieces, really hard. I had an 8N more than 25 years ago, and its starter needed new bushings then.

New brushes are straight across and have a radius near that of the commutator, but a very used commutator is not straight. It has ridges and grooves around it. You need the WHOLE surface of the end of the brush against the commutator to carry the couple hundred amps. When you don't turn the commutator and sand the brush to fit (with a strip of sandpaper wrapped around the freshly turned commutator) you concentrate that current in a small area which leads to burning damage to brush and commutator. And poor starter performance because of the power lost there.

Gerald J.
 
John:

Thanks for the clarification. I'm fairly mechanically inclined but tractor ignorant. I have only been working on this 8N for the past two years. I really appreciate your help.

Regards,

Charlie
 
Thanks for the recommendation. I do have some of the blue emory rols for plumbing that should work well.I think the brush that I used to clean the terminals earlier had some WD-40 on it.
 
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