Alternator melted the wiring

[blueka]

99 Explorer Sport 4.0 OHV 5 speed manual trans 4x4

I sold this Explorer over 14 months ago, after I fitted a new transmission to it...

The woman I sold it to has been texting me for the last few weeks asking for a boost every few days, then she texted saying she was stranded at the side of the highway, that it was totally dead...

She gets it home and takes the alternator off... and the pictures show what I'm dealing with... the ring on the wire has melted off and scorched the back of the alternator

When I touch the big black wire to the bracket for the alternator, it sparks...

It has been suggested that there is a crossed wire somewhere, other people have said, that the big wire is, in fact, a positive wire and that's why it's sparking...

So, is that big wire a ground or a positive wire? If it is a ground, I've got to find a crossed circuit...

Any help/suggestions, as always, greatly appreciated...

Thanks peeps

Si

 

[my98nnj]

That terminal and wire are battery +. The terminal on the alty should have plastic around it shielding it from the body of the alty. It's clearly melted away, most likely from excessive heat caused by a poor connection.

 

[Rick]

What is the condition of the battery? Could it be that it was trying to put juice into a shorted battery?

 

[Rick]

Or, did the insulator break down between the pos post and the case causing the short?

 

[blueka]

it was massively cold at the time (-40f) the battery was old, and on its last legs... so, I'm guessing that was the problem...

Thanks guys, I'll throw a cover on it and get it back together...

Si

 

[jonlax]

Internally shorted battery or poor connection.

 

[koda2000]

Internally shorted battery or poor connection.

or a bad ground.

 

[Texan01]

bad ground on the alternator wouldn't cause this unless it shorted internally. Theres 3 bolts that hold it on, so you'd have to lose all 3 of them to even get it that hot.

I'm thinking the bad battery burned the B+ terminal.

 

[corkey]

or somebody hooked a booster cable to it, thinking it was the ground ??

 

[madbutcher]

that happend to me yesterday to.. but i broke the connection on the back of my alternator to.. so i need to get a new one.. or find a way to connect the cable

 

[Flash]

The woman I sold it to has been texting me for the last few weeks asking for a boost every few days,

If she needs a boost every few days then there's something ####y with the battery or the charging system.

From what you've said and the pics I'd say it's a short in the battery.

That big wire supplies volts to the battery, if the battery has a short then the big wire shorts out in a BIG way.

I'm guessing that you're not the only supplier of volts her ladyship has asked for a jump from so you really don't know what's been happening under the hood.

 

[SoNic67]

Water on that terminal can lead to an external short-circuit.
Since at that point we have the whole alternator short-circuit capability (some 100A) and at least 175A from the battery (via the Mega-Fuse), that added current will melt any connection.

A loose connection won't do that damage because it will take just the battery charging amps, that are fairly low (20A, even lower with a loose contact).

PS: You didn't need to resurrect a 11 month old tread... you could make a new one.

 

[blueka]

It was a shorted battery

Si

 

[Flash]

that happend to me yesterday to.. but i broke the connection on the back of my alternator to.. so i need to get a new one.. or find a way to connect the cable

It's only a bolt but make sure it's insulated from the alternator body.

 

[Flash]

It was a shorted battery

Si

Easily fixed. It might have happened when the lady got a boost from someone and they put the cables on the wrong way.

 

[madbutcher]

It's only a bolt but make sure it's insulated from the alternator body.

need to drill it out and make some new threddings

 

[SoNic67]

It was a shorted battery
Si

The battery was damaged by the external short on that alternator bolt.

 

[BustedKnuckles24]

You'll need to replacevthe battery, alternator, and that charge cable. I would not trust any of them after seeing this much damage. And I don't like re-doing work. Replace it all will prevent problems from hidden damage.

 

[SoNic67]

Yep, good call. Probably now the cable itself (between alternator and megafuse/battery) is not in that great shape either...

 

[blueka]

the battery was shorted out due to the idiot boosting it with the cables the wrong way... I put a new terminal on the wire and called it good, it's not my truck, I did the repair for free on a truck I sold, over a year after I sold it... it's still running fine...

Si