MavsAK

So, going home from work just as I was turning out of the parking lot I get the lovely smell of burnt plastic for a moment then gone.

Running on battery voltage all the way home...battery light is on and running at 11.5 volts (all the way home)

Open the hood this morning looking for signs of a fire..and right off the alternator's big power lead, it's burned itself through the wire entirely, just after the connector.

Now the car is an 89.

Just a case of a wire gone bad? Or something else entirely?

Going to go get a new wire to splice into that one, and a new eyelit.

c4cruiser

Be sure to check the entire length of that wire!! It will go thru the black plastic wire loom and if it got hot enough to melt the insulation, it may have also damaged other wires in the loom. What does the red wire on the positive battery cable look like?

Once you have recharged the battery and replaced the wire, check the voltage at the alternator with the engine running. Look for a voltage around 14.1 to 14.3 initially. It should drop down to around 13.7 or so after a couple minutes of running.

MavsAK

Red wire on the battery looks AAA. Still very flexible and malleable, great insulation, and no corrosion on the ends.

The other wires at least near the burn looked pretty good. It burned the loom that it rested ontop of but the wires inside the loom look alright. Going to chase it back a little farther.

WVZR-1

It would seem maybe odd that the fusible link didn't destruct. You maybe need to be looking further upstream at the battery jump block.

Churchkey

Typical issue caused by high resistance @ the alt/battery wire connection.
Your alt is probably ok.
Disconnect the battery.

Exercise caution removing the nut that holds the broken wire connector on the alt stud you do not want to spin the stud. Try to hold the nut that retains the plastic insulator to the housing then remove the outer nut. If the insulator is damaged replace it. Check the nut that retains the insulator to the housing it needs to be tight. Clean the stud, a new nut + lock washer. Use HD crimp connectors, push the metal connector out of the plastic cover & solder the connections. Shrink sleeve the in line splice. A 90 degree ignition wire boot for 7mm wires makes a good alt stud cover.

89onlyZ51

That crimp weakens with vibration and then heats up with the higher resistance as mentioned. Go to a marine store and get a new terminal as the marine-grade stuff (tinned copper) is much better than the aluminum crap at the auto parts store. Before crimping, make sure the wire is VERY clean (cut off the burned section if you can), or the problem will return.

89L98TPI

Same thing happened on my 89. Fried power wire at alt and also a burnt fusible link behind the battery on distribution block.

I spliced in some new wire at alt and replaced fusible link. Charging system now works.

MavsAK

Thanks guys. I'm alot less worried now. (burning wires always scares me. This is the first time I've had one off the alt though! and first for this car!)

soon as I can get out, I'll go pick up some more wire, a new connector, and fusible link.

Tom400CFI

When you make a new wire, rather than smashing (crimping) thi connector on, fill it w/solder, stuff the wire into it while the solder is still liquid, let cool Best connection you can make. THen put some shrink wrap on it to protect it all, then the boot.

MavsAK

yeah I had to pick up some new solder today. Along with some 8 gauge wire...apparently I used it all on another project already. I'm guessing I used it on my Z28 since that car was an electrical fire waiting to happen, and the connectors....naturally I lost my wire strippers and crimpers too. I'll probably end up finding the stripper and crimper tomorrow when I finish this unscheduled project.

picked up some more electrical tape, and shrink tubing. And some new plastic wire loom.

aDigitalPhantom

In addition if you tin the wire before going to stick the end on the end will solder easier, and the wire itself will have a better connection.

Cliff Harris

I doubt that will work. When you poke the large cold wire into the terminal the solder will instantly solidify and you will NOT have a good connection. You need LOTS of heat on wire this size. The problem with lots of heat is that the insulation will melt. Usually when that happens it shrinks and pulls away from the terminal.

The way to do this that will work is to crimp the terminal on the wire and use a solder pot to solder it on. The solder pot has lots of thermal mass and will keep the terminal and wire hot enough to get a good connection quickly. You don't have a solder pot in your toolbox? In that case you'll have to be creative.

I know how I would do it, but I've got soldering tools that most people don't have (like a 6" x 6" x 1/8" sheet of asbestos that will take a LOT of heat, which makes a good backup for holding parts while soldering). ...and a big honkin' soldering iron that uses about 200 watts.

Tom400CFI

Ayuh. It works though, in spite of your doubts.

I do it all the time, and have been for ~20 years. In fact, I just built two wires last week using that method for some snow cats I'm working on; one I made was 8 gauge to power a passenger cabin, the other was a battery cable.

I'm sure that heating the wire too won't hurt, but you (I) also don't want to char the insulation in the process. If you hold the wire over the ring terminal being heated, you can heat both at the same time w/judicious management of the torch.

MavsAK

All done.

Fusible link was fine.

And now for the first time I have 14.50 volts at start up and idle. Took care of some other things while I was in there. Cold...but worth it

Cliff Harris

I assumed from the way you stated it that the wire was not heated. That changes things... If it works for you, that's the important thing.

I've been soldering for over 50 years, so I have some experience there...

Tom400CFI

It works both ways; whether you heat the wire or not. It probably works better with it heated, but I've done it both ways and had a solid, long lasting (rest of the vehicle's life) repair.

My overal point wasn't about what soldering method to use; IMO that is a personal thing. My point was to avoid the smashing-a ring-connector-onto-a-wire-and-call-it-good method altogether, and do it a better way using heat and solder. You said "I doubt that will work", so I pointed out that it will work, and has worked well...many, many times. What ever method you use to solder, in this case, the result is better than "good enough".