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Old 03-11-2018, 01:47 PM   #1
Corey'sgotachev
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Pics of Burnt Ground Wire Battery to Fender

Was trying to start the truck. Starter turning over slow and I noticed smoke coming from under the hood. I have read about the need to ground the front fender on a 70 chevy. Could my crappy battery connection force current through the fender on its return to the battery?
What kind of battery connections do you all use?
What else would cause this wire to burn up?
I've had this truck for a year with no problems. Could it be that since I haven't driven it much (broken rear diff), the battery has drained and needs replacing?

Thank you for your help!
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Old 03-11-2018, 05:16 PM   #2
dmjlambert
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Re: Pics of Burnt Ground Wire Battery to Fender

It’s hard to comment without knowing where those wires are going from the terminal. I don’t think a poor connection or lack of ground will cause the wiring to melt. A short or incorrect connection will. I am not a fan of those clamp on repair connectors, I learned to pretty much hate them.

A stock connection to the battery + terminal has a 16 ga fusible link to the terminal block on the fender and the big wire to the starter. The battery - terminal just has a big wire to the block.
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Old 03-11-2018, 08:49 PM   #3
franken
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Re: Pics of Burnt Ground Wire Battery to Fender

Assuming that's the - terminal, you lost a ground somewhere that wants much more current than the burnt wire could supply so it fried. I'd be looking at the battery to engine ground.
As stated above, the ground goes to the engine, then the cab, then the frame via ground straps. The + side has a low current wire from the battery to a junction block on the fender.
BTW, the battery to a junction block should be or have a fusible link. This prevents the dreaded carbecue scenario. Guess how I know this.
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Old 03-11-2018, 10:07 PM   #4
87Skier
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Re: Pics of Burnt Ground Wire Battery to Fender

If it happened while starting, then the current from the starter was likely returning from the starter through the small wire. This is because of a bad primary cable or high resistance from either end of the cable.

I would replace the entire cable, and clean the block connection point with first a wire brush, then metal file or sand paper until it is shiny.
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Old 03-11-2018, 11:12 PM   #5
68c10airstream
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Re: Pics of Burnt Ground Wire Battery to Fender

Those terminals that bolt to the lead cable end are considered an emergency repair. As a rule of thumb, if the repair has exposed wire strands, oxygen is not your friend. I would hate to tell you how many of these repairs i deemed bad and replaced with a new good quality cable, and shining up every attachment point along the way. The small wire burnt because the fat wire wasn't supplying enough for the starter. If you can still get "standard" brand wire cables they used to be really well made.

If you want to rely on this to work correctly the absolute least would be to replace all of the ground cables, remove the braided straps at the firewall and valve covers and shine up and re-install. Rh inner fender down low has a ground between the inner fender and the frame rail. Water and dirt love to spray on this area. Think it's still good connections? Remove and check! This is the ground for the frame to get the ground back to the tail light area.
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Old 03-16-2018, 04:54 PM   #6
'68OrangeSunshine
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Re: Pics of Burnt Ground Wire Battery to Fender

If that's the positive terminal -- you blew the Fusable Link.
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Old 03-16-2018, 05:24 PM   #7
Kudzupatch
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Re: Pics of Burnt Ground Wire Battery to Fender

Quote:
Originally Posted by 87Skier View Post
If it happened while starting, then the current from the starter was likely returning from the starter through the small wire. This is because of a bad primary cable or high resistance from either end of the cable.

I would replace the entire cable, and clean the block connection point with first a wire brush, then metal file or sand paper until it is shiny.
Agreed! That wire had too much current (amps) going through it and that is why it got hot. I would money on the main ground cable didn't have a good connection from the battery to the motor for some reason.
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Old 04-03-2018, 07:31 PM   #8
Icebox240z
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Re: Pics of Burnt Ground Wire Battery to Fender

Recently had similar electrical gremlins pop up in my '72 K20. Long story short (for once)...I just got a couple new grounds made up out of fine strand copper core welding cable, 1ga. for front of block to frame, and 4ga. for back of block to body/firewall (to replace the old copper braided strap from rear valve cover bolt). My chevy buddy pointed out that my motor has aluminum valve covers and the grouns through just the steel bolt to the head probably isnt best and that there might be a better spot on the back of the block. Anyone familiar with any good alternative locations? The attached pic shows the two new grounds at top, old braided copper in middle, two off the shelf new braided cables that'd i had considered using.
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Old 04-04-2018, 11:58 AM   #9
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Re: Pics of Burnt Ground Wire Battery to Fender

Quote:
Originally Posted by dmjlambert View Post
Itís hard to comment without knowing where those wires are going from the terminal. I donít think a poor connection or lack of ground will cause the wiring to melt. A short or incorrect connection will. I am not a fan of those clamp on repair connectors, I learned to pretty much hate them.

A stock connection to the battery + terminal has a 16 ga fusible link to the terminal block on the fender and the big wire to the starter. The battery - terminal just has a big wire to the block.
I always solder those things.
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Old 04-09-2018, 11:04 PM   #10
Icebox240z
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Re: Pics of Burnt Ground Wire Battery to Fender

FWIW...turns out I had a dead short to ground: After replacing the starter, I poorly positioned the positive battery cable...and mistakenly didn't clamp it into the cable holder bolted to the frame...when turning into the driveway from an awkward angle, the cable got pushed up into the hot exhaust manifold, melted the shielding and caused a short to the block/exhaust. LESSON LEARNED: USE THE CABLE HOLD DOWN AND MAKE SURE THE CABLE IS POSITIONED APPROPRIATELY SO IT WON'T CONTACT THE EXHAUST MANIFOLD.

(Yes...I openly admit this was definitely my mistake, and I paid for it.)
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Old 04-10-2018, 03:12 AM   #11
VetteVet
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Re: Pics of Burnt Ground Wire Battery to Fender

Thanks for the feedback and don't beat yourself up too much because we have all screwed up at one time or another. I have a clamp on the frame rail just to prevent this from happening. Working on aircraft makes me paranoid about these issues.

This is one advantage of using the Ford solenoid besides the heat soak problem. If the battery cable is connected to the Ford solenoid as a two piece cable, the part on the starter side of the solenoid is dead except for during cranking.

This wouldn't work if the starter solenoid was used as a junction like the 73 and up years
but one could always use the battery side of the Ford solenoid for that.

Here is a picture of how it would work.

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