Need help! 57 210 w/350 enigine keeps melting the wire between the alternator and the battery

[57chevy210blk]

I have inherited a '57 210 2 door hardtop from my father in law who recently passed and need help diagnosing electrical issue. The battery was dead the other day and since it had been in there for a while I decided to replace it. Went to the auto parts store and got the new battery with a little bit more cold cranking amps. Upon installing the new battery once I hooked up the negative battery terminal it melted a 10 gauge black wire running to the back side of the alternator. I thought that maybe this wire was old and was shorting out some where on the frame or body, so I replaced it and tried the battery again. The same thing happened. Could use some help with this. The engine is a 350 , the alternator says (SAE J1171 Marine) on the back of the casing where the wire in question connects.
10103The wire in my hand is what keeps melting.

Thanks for any input,
Mike

[chevynut]

First of all, welcome to the site and congrats on getting a 57 2DHT. :cool:

I would disconnect the wire from the alternator and see if it still sparks or gets hot when hooked up to the battery. If it doesn't, your problem is probably the alternator if nothing else is connected to that wire or at the alternator...take it down to a parts store and have it checked out.

[chevynut]

Looks like you could use a new battery tray while you're at it. ;)

https://www.partsgeek.com/ss/?i=1&ssq=1957+Chevy+battery+tray&x=0&y=0

[57chevy210blk]

Thanks I will give that a try. I've been looking at wiring diagrams and was wondering if it's odd that this wire goes to the negative battery cable?

[chevynut]

Thanks I will give that a try. I've been looking at wiring diagrams and was wondering if it's odd that this wire goes to the negative battery cable?

Oh, I didn't catch that! The wire from the stud on the alternator should go to the POSITIVE side of the battery! The alternator is grounded to the engine. But I don't understand where the current is coming from if you're grounding the alternator stud. Is there another wire?

You should have a large battery cable from the battery positive terminal to the starter solenoid. Then there should be a wire from the positive terminal of the battery to the stud on the alternator. Alternatively, you can have a wire from the alternator stud to the starter solenoid. If there's more than one wire on the alternator stud look to see where it goes.

This assumes the alternator has an internal regulator too.

[57chevy210blk]

Ok that's what I thought based on the wiring diagrams. The interesting thing is this is how it's been set up for years and worked fine until I just put the new battery in. I will swap that over and see how it goes. Appreciate the information and knowledge.

[chevynut]

Ok that's what I thought based on the wiring diagrams. The interesting thing is this is how it's been set up for years and worked fine until I just put the new battery in. I will swap that over and see how it goes. Appreciate the information and knowledge.

Before you go swapping things I would look to see how things are actually wired up. It's hard to believe that the alternator stud would be connected to ground. Are you sure the battery you got has the same terminal configuration as the old one? Since the cable in the pic has a fused wire on it, it's probably not the ground cable.

I'm guessing you've hooked up the battery backwards.

[57chevy210blk]

Yah , I am wondering if they wire up the Black cable as positive and the red cable as negative.

[chevynut]

The negative battery cable should go to the engine block or frame. The positive cable should go to the large terminal on the starter solenoid.

[scorpion1110]

Just a quick comment, as I am installing a Kwik Wire harness in my 55 and am doing the engine right now.

There should be a wire to the hot lug on the alternator and as CN said it needs to come from a hot source like the hot on the starter or battery (In my cause the harness is pre-wired for the alt set up) . This assumes a one wire internally regulated alt. Some alternators also have a jumper from the hot lug to the two prong with the second prong having the alternator exciter wire. This is a three wire set-up.

Also as CN says the alt should ground to the engine; and the case technically does via the bracket. But I think bad grounds are a wiring demon that we fight all the time. The wiring harness I am installing, suggests a 6 gauge wire from the alternator housing lug at the bottom to an engine ground. So in this case, again with a one wire internally regulated alternator, you would have power to the hot lug at the top, and a ground at a lug on the bottom.

Maybe this will help you out.

Scorp