Battery Ground melting....

[Art]

Hello,
I have an '84 GMC 1/2 ton, that I picked up a few years back. It runs like a top, but recently it's been hard starting after the motor warms up. When the engine is warm the starter will churn slowly or click, and the wire from the negative battery terminal to the core support heats up and melts. Cold starts are fine.
I know I must have a short somewhere, but I can't find it. I've gone all through the harness/starter looking for a problem, and have also tried a different battery. I'm beginning to think it might be something else, since the heat plays such a role. Any input would be greatly appreciated.

Thanks,
Art (Seminole, FL)

[Grim Reaper]

Uhhhhhhh something is big time not right.

Ground path is Neg to the battery to the engine. usualy the Alternator bracket. The body is ground off a strap from the back of the passengerside head to the fire wall next to the blower boxes.

Your truck proably has a bad grounbd cable from battery to the engine (the big thick one) and it's trying to pull ground throught the strap on the back of the head, through the fenders to the coresuport.

REPLACE THE FAT GROUND CABLE TO ENGINE NOW. Make sure that it is a clean paint free connection.

[Free88]

Do a starter draw test. Starter maybe grounding out due to worn brushes and when its warm too n=much draw on start up causing too musc voltage draw and melting the wire. Try by either test or replace the starter. May help.

[Blue Beard]

I had a short like that, but mine ended up being the positive cable against the block behind the exhaust manifold........

[c10boob]

Removed.

[chengny]

Here is the cab body to engine ground strap. I didn't have a photo of it bolted to the cylinder head but the arrows indicate where the loose end goes:



Move the battery negative cable to the alternator bracket.

And, if your negative cable is getting hot to the point of melting the insulation, you have a dead short to ground in the positive cable. It will be in the run between the battery positive and the connection at the starter/solenoid. That is the only unfused lead in the entire electrical system. If it there was a short to ground anywhere else, a fuse would blow or a fusible link would melt.

[mattcrp1]

Do a voltage drop test on the cables. It sounds like you have a bad ground cable and the starter circuit is looking for a path to the battery through the core support ground. I would guess if you changed the ground cable or added a "jumper" from the battery to the engine, as a test, it would solve your issue.

[KQQL IT]

Ground wire needs to be same gauge as the positive.

[rich weyand]

The OP said the battery negative to the CORE SUPPORT is melting. This means that the negative battery cable from the battery to the alternator bracket is loose, internally corroded/broken, bad connection, something, and the starter current is finding another path back to the battery, but that ground strap to the core support cannot handle the load.

Replace the negative battery cable to the alternator bracket.

[50seven]

I would suggest new battery cable leads pos & neg, new solenoid & starter. Disconnect the battery in the mean time.

The starter sounds like it is pooched. You may also have a direct short?

[motornut]

as mentioned you need the big Batt Neg to the Alt bracket in good contact
for some reason it's finding a easier way.

[rich weyand]

Originally Posted by 50seven

I would suggest new battery cable leads pos & neg, new solenoid & starter. Disconnect the battery in the mean time.

The starter sounds like it is pooched. You may also have a direct short?

There's nothing wrong with the starter. The voltage drop through that small ground wire to the radiator support can't handle enough amps to turn the engine over.

[50seven]

I don't propose to be phsychic like rich and I can't see your truck from my house so I have to go by logic.

SBC starters are notorious for hard warm starts when they are worn out. Your cables have seen heat to the point of melting insulation so probably need to be replaced. Might as well go thru all the grounds while you are at it as Rich knows for sure to be the problem.

I hope it is just a simple fix.

[rich weyand]

No psychic about it. He said that the cable to the radiator support was melting. Why would that little wire be carrying so much current during starting? Because the big wire that is supposed to be carrying the starter current is broken. So the heavy battery negative cable to the alternator support is either broken or poorly connected.

[Just call me Sean]

Ten year old thread, I hope it's fixed by now.

[50seven]

Sure.

You might be right but I doubt it. If the Neg was that bad to the alternator the battery would probably not be charging properly either. As I said before the starter is more than likely pooched but I'm just using logic? The cables IMO are worth replacing aswell because they have been taking a heavy amperage draw....... just my .02

[50seven]

Haha Ten year old thread.... that's awesome. Wish I was phsychic I would have known.

thanks Sean

[rich weyand]

For giggles, I searched the OP to see if he ever posted the solution.

It was a bad ground strap.

http://67-72chevytrucks.com/vboard/s...ad.php?t=91209