Starter seems to be shorted out

[31 Woody]

I am having some starter troubles. Was trying to crank over a new engine last night, the engine is tight so the starter was working hard. While cranking, I noticed one of the cables was getting quite hot-it was the cable to the starter--so I stopped working for the evening to let it cool and so I could get another cable. I put the charger on the battery to recharge before turning in.

Today, I replaced the cable that was hot with a new 2 gauge cable. Unfortunately, I barely got a click out of the starter. I chased through all the connections, fixed many, then went to pull the starter. I have 6.4 volts at the starter switch--just FYI.

Out of the car the starter wouldn't turn over with cables, but the armature shaft does spin by hand. I pulled it apart and looked it over, cleaned the armature contact point and brushes, then put it back together and nothing! I took it apart again and carefully looked everything over. I paid special attention to the cloth wrapping on the two brushes so wrapped-one was questionable but I assembled it being cautious to ensure the wrapping/wire was not grounding out somewhere. This time it did run on the bench, but not very fast. I tried it in the car and click, that was all I got out of it. I can't see how you could change those brush wires if they even are the problem.

Any ideas?

[Kurt in NJ]

When you took it apart were there any small specs of silver around the armature where the windings connect to the commutator---and on the field coils opposite that area? ---when a starter is forced to wotk too long, under too much load, and with low voltage a lot of heat is built up that can melt the solder ---the silver specks , it is called throwing the solder ---another thing that causes slow cranking is worn bushings ---the armature drags on the field coil pole pieces ---the armature needs to be close but it can't touch, if it is touching there will be marks from rubbing, and if let go too long the heat can damage the insulation causing shorts.

The brush wires for the ground side screw in, the insulated brushes are soldered in to the field coils, to solder those it is best to have at least a 250 watt soldering iron, I usually use a 600 watt iron because it heats the connection very fast with less chance of cooking insulation, I also use it to resolder the windings to the commutator

[SAJ]

My 6V starter was always sluggish. The previous owner was an electrical engineer and the car had new cables when I got it. So I ran it for 2 years before deciding to have a good look at these cables. They looked fat but when I measured the copper they were 2 guage. I made up new cables from 0 gauge using soldered-on heavy terminals and my starter is now really brisk. There was about 2 volts drop over the old cables and isolater switch while cranking . Before replacing the no.2 gauge cables I had reco'd the starter and remade all the connections. But there was not enough copper in these smaller cables for a high compression motor to turn over well.
I also got caught putting an incorrect long bolt into the rear starter fixing and it jammed on the flywheel. Easy to do when you faced with a box full of bolts that you didn't take out in the first place!
I believe I have read here many times that 2 gauge is ok for 12 volt but too small for 6 volt.
My old cables looked really heavy but it was very thick insulation and not copper when I eventually cut one up.
SAJ in NZ

[columbiA]

You can make up good heavy cables by using heavy electric welding cable.Better to have a very heavy guage than not enough.So many guys change over to 12 V when all they really needed was heavy cables & good clean connections & grounds.It will crank over very fast if done right & the engine does not need to crank over fast to start.S starter that turns over fast is drawing much less amps which leaves more voltage for ignition.

[SAJ]

ColumbiA. Good point about more starting volts available when the starter gets up to speed properly. I certainly noticed my car starts more promptly with fatter cables. Plus my genny now holds plus 2 amps with headlights on at 30 mph. It was about 2 amps discharge before i changed the cables. No change made to third brush. I have a Fun Projects regulator/cut-out so max demand will give 15 amps if needed.
SAJ in NZ

[31 Woody]

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Thanks for the responses. I noticed a few, and by that I mean just a couple of shiny specks that I think could have been solder that are now on the area I was working, but it does not seem enough to kill the starter. I will have to look again at it, but did not see any obvious points of contact either. But good thoughts on what to look at--thanks!

As for going to 0 gauge wire, I thought about that, but even in Los Angeles, your choices of stuff to buy is a bit limited on a Sunday. I may upgrade that as well, it is easy enough to do and not all that expensive either.

Still have a dead starter though.

[jimvette59]

Have the armature checked on a growler. I think and not enough to kill a starter does not work. Get it right on the bench. JMHO.