Hi everyone.


I've been a long time viewer, first time poster to this forum, but I need some help / expertise that I haven't been able to find already posted.


I have a 68 convertible, mostly all original, that I have been learning to work on, and this weekend had a failure I don't know where to start diagnosing.


I had recently installed Doug's side exhaust headers and side tubes, gotten everything back together, and was taking her out for a test ride (sounding absolutely amazing, BTW) when all of the sudden I lose all power and the car shuts down.


I push her into a vacant lot and call AAA for a tow. Looking into the battery compartment I find that the negative connector has MELTED off of the battery and separated from the negative cable.


What could have caused this?


1. Checked the ground when I got it home, and it is still attached to the frame - should I clean / attach somewhere else?


2. When installing the headers the alternator had to be moved and I reinstalled using a slightly longer belt since it moved about an inch away - could this somehow send too much voltage to the battery and cause the melt?


3. The side tubes are attached directly to the frame rails, to the headers, thus to the engine block - could the fact that the ground wire is also attached to the frame case some sort of short?


Any other thoughts / things I should check?


Thanks in advance!

 

Check for melted wires around the starter. Common problem after changing exhaust. Be very careful how the wires are routed!!! The battery terminal must have had a bad connection, and the ultra high current thru it caused it to melt.

Clean/fix both terminals, inspect all the power wires and grounds....

 

Thanks, @mikem350 I will look at that tonight.


I don't have a switch installed at the battery so I had been taking the cables off the battery when not in use and the connections might have been loose.


The only thing that worries me is that I replaced the negative terminal and when I went to re-connect the battery I got heavy sparking when I went to connect the positive cable.

 

It might have just been loose on the terminal

 

If you got heavy sparking when you connected the batt terminals then you had a dead short. You should have stopped right there and located it. Look around the starter area.

 

Hi Hud,
Welcome!
I'm sorry your first posts need to be because of a problem.
There are quite a few grounds on the car.
The 2 heaviest are:
The one you found from the negative terminal of the battery to the frame. Did you replace the cable you found melted?
the second is an equally heavy cable from the engine block to the frames bracket for the engine mount. You should check that if you haven't already.
You should also look at the connections on the starter and the alternator to see if an unshielded connection is touch something it shouldn't be and causing your problem.
Good Luck!
Regards,
Alan

The battery ground to the frame.


Ground cable at engine block.


Ground cable at frame bracket.

 

 

Thanks, Alan! I see your replies all the time as I am reading through threads, so I am honored to have gotten one!
I have not replaced the cable, however I made a fresh cut when I installed the new terminal end on it. I traced it down through to the frame and couldn't find anything else wrong with it, so I left it be.


Thanks for the pictures here. Granted, I'll be navigating an engine bay put to shame by the one in the pics, but they should help me sort out if I lost connection in these places.


I'll also look at the starter to see if there is anything off there.


Rob

 

Hi Rob,
There's NO reason to feel "honored".
Believe me.!
If I can be even a little help then I'm pleased!
Regards,
Alan

 

There may be a short to ground, possibly caused by the new installation of the headers. The cable melting at the battery terminal was caused by a corroded or poorly crimped connector. That would cause electrical resistance at that point, voltage drop and heat. You're lucky the car didn't burn!

 

I'm in agreement with the others, you have a 12 volt wire going to ground. The ground wire should not spark unless something is turned on shorted.
Recheck around your headers your are looking for a wire touching the new exhaust.
You are going to need learn how to use a volt meter capable of reading 12 DC.
I am sure 68 has fuse able links that may have blown?

 

Well, you guys couldn't be more right. Took a look and below is what I found. I haven't looked at a diagram yet but I'm guessing that's the ground that's melted to the pipe

At least I've found it, but I do feel bad for burning up a 48 year old relic.

 

Hud. Thats not the Grounded Cable thats the B+ ,positive, from the battery. DO NOT under any circumstances attach the battery until you move that cable away from the header and repair the insulation that is damaged. You have a DEAD SHORT per your photo.

 

Thanks, @ayellow56 . I was just looking at diagrams and saw that it is the battery cable and not the ground.

I assume that I will need to completely replace this cable, as opposed to trying to doctor it up, correct? It was on there pretty good. I have plans down the road to replace the interior carpet that this cable runs under, but does anyone have a suggestion for an interim fix? Would splicing a new end to this cable be a SAFE "bubba fix" to get her running again or should I wait till I can replace the entire cable?

 

You don't want to splice it. If anything, put a couple of layers of heatshrink tubing over it and make sure it is clear from touching again. If that part of the wire didn't touch anything then a bare wire would still work meaning that the heatshrink will be fine for insulation. It is rather hard to find anything that safely protects meltable parts from direct contact with exhaust tubing so it's best to keep some distance with anything that can melt.

 

And this is IF when you pull back the melted wire...you can tell that it still has the strands connected where it melted. Instead of ...lets say...half of the wire stands have actually broken.

And this melted positive battery cable could have caused the damage at the battery....and it could have been caused by a loose negative battery cable connection at the battery. Due to the ground path not be 100%. The resistance at the battery was great enough to melt there instead of what normally would occur is the positive battery cable being to melt like crazy at the point of where it is grounded out.

Because we also know that IF the alternator is working correctly...you can disconnect a battery cable and the car will still run....and with that being known....your loose negative battery cable could ahve already started to fail due to being loose. Which I have seen before .

DUB

 

Wrap the wire and the exhaust header with fiberglass header-wrap. That will act as a spacer and also offer some heat protection.

 

Hi Hud,
The horse is already out of the barn….. but….. originally there was a spring clip that that held the battery cable and the other solenoid connections tight against the body of the solenoid.
Perhaps yours was missing so it didn't get put back on after the headers were installed.
Glad you found what you did without having the word 'fire' enter the discussion!
Regards,
Alan

The clips are readily available so you may want to add one as part of your 'fix'.

 

[QUOTE=Alan 71;1593431353]Hi Hud,
The horse is already out of the barn….. but….. originally there was a spring clip that that held the battery cable and the other solenoid connections tight against the body of the solenoid

/QUOTE]

Alan your pics are unbelievable! All these years working on Vetts and Chevys and I have never seen that clip!

BUT I have seen MANY melted cables

 

HUD, One last thing to remember when you've made all the repairs and go to reconnect the battery cables. RED+ is always the first one on (when hooking things up) and it's the last one off (when disconnecting). Same for when you attach any jumper cables.
Duane