Alternator issues. Stuck on the road.

[Kevin 007]

Out of town, cold weather and the alternator decides to bite the dust. Or at least I think it did.

Truck in question is my 84, factory alternator, no 3G or anything upgraded. Was driving for a few hours with the heater on high and with my lights on (during the night) along with two extra lamps that come on with the high beams. So probably overloaded the little factory alternator, not too much of a surprise but what I found odd is that the fusable link casing coming from the "Bat" stud on the alternator was all melted and the wire under the casing was glowing red when looking at it closely in the dark when engine was running, not charging at this point. The fusable link itself is actualy still ok aside from the melted coating/cap its the short section of wire from the link to the alt stud that glowed red and broke when I tugged on it.

So in the a.m im going to put a new alternator on it and I want to put a new fusable link in place and then see what happens (hopefully thats all thats wrong). Now I don't ever recall seeing fusable links in parts stores. Do they even exist or do I have to install an inline fuse? And if so, what kind of amprage will I need? This is on the wire coming from the "bat" terminal on the alt. A 3G swap is planned for the future but not now as I just need to get it going and I have no extra tools or parts to be doing a 3G swap.

Thanks folks.

 

[Michael Fowler]

This from the '86 FSM...
The fuse link is a short length of a special Hypalon ( high temperature) insulated wire....it is several gauges smaller than the circuit which it protects.... The higher melting temperature properties and additional thickness of the Hypalon insulation will usually allow the undersized internal wire to melt and disintegrate within the Hypalon casing with little damage to the high temperature casing other than discoloration and/or bubbling of the surface...the bare wire will seldom be exposed. When it becomes difficult to determine if the fuse link is burnt open, perform a continuity test.
Production fuse link s have a flag molded on the wire or on the terminal insulator. Color identification of the flag or connector is Blue-20 Ga wire, Red- 18 Ga wire, Yellow-17 Ga wire, Orange-16 Ga wire, or Green-14 Ga. wire.

To test the fuse link that protects the alternator, make certain that the battery is OK, then check with a voltmeter or 12 volt test light for voltage at the BAT terminal of the alternator. No voltage indicates that the fuse link is burnt out.


The FSM recommends that replacements use a butt connector and then be soldered in using 60/40 rosin core solder. I


Hope this helps.

 

[OLDBULL8]

Here in the States, Autozone carries the fusible link wire, comes on a small roll of 5 or 10 foot.. I don't think the Alt. is bad, could be one of the batteries cell shorted out, or the chassis wireing it self, in any case, it needs to be checked out.

 

[franklin2]

If they are street legal, two extra lights being on are not going to overload your factory alternator. Take the alternator off and get it checked or get a cheap voltmeter at the store and verify if it's bad. It may not be.

 

[ToughOldFord]

I'm pretty sure that wire going to the alternator is NOT a fuseable link, just regular wire.

Mine got hot and started smoking on me, it was just a bad connection at the terminal.

 

[icanfixall]

I agree with the above posting. I feel the alternator is fine but would be checking other places for this failure. Might very well be a loose ground or a bad battery.

 

[Kevin 007]

Thanks for the replies. I will be purchasing an alternator anyways before getting a ride out to where the truck is just in case it is shot, but will have to install some kind of fuse im thinking on that wiri that burnt up. Dont know... Or should i just wire straight to the battery? Thanks!!

 

[chris142]

It needs some sort of fuse! Look in the fuse section for a large fuse that you can wire in place of the fuse link. Im assuming that your 70a alt has around a 100a fuse link. Grab a few different ones. Start small say 60a and see how that works.

 

[ToughOldFord]

Put a fuse on it and you'll blow it every time you load that alternator.

You could try to out-fuse the load, but what about if you do the 3G swap? Going to put a 150 amp fuse in there?

 

[theguruat12]

As Oldbull said, AutoZone has fuse links, but better than 5 feet, they have little 6 inch ish pre-cut with a butt connector packages for like $3. I replaced mine since it was looking iffy from the P.O.

 

[riotwarrior]

Fusable links are easy to make, if your charge wire is 10 gauge, just insert a short section of 12 guage, that's the fusable link.

IIRC it's just one wire size down, I've made maybe 20 in a lifetime, and no problems, at all over the years.

Maybe yer VR is to blame, if getting an ALT get a NEW VR as well, then if it's bad you are not making multiple trips.

Voltage Reg bout 20 bucks,

JM2CW

 

[OLDBULL8]

The wireing diagram for your 84 yr. shows a 14Ga (Green) fusible link from the VR to batteries. Damn, diagram won't enlarge for me, maybe you can.

 

[franklin2]

Fusable links are easy to make, if your charge wire is 10 gauge, just insert a short section of 12 guage, that's the fusable link.

IIRC it's just one wire size down, I've made maybe 20 in a lifetime, and no problems, at all over the years.

Maybe yer VR is to blame, if getting an ALT get a NEW VR as well, then if it's bad you are not making multiple trips.

Voltage Reg bout 20 bucks,

JM2CW

An official fusible link has special insulation around it so when it burns out it won't catch everything around it on fire.

 

[rhkcommander]

Ive been using a resettable fuse, its rated for 200 amps i think ~ on a 130 amp 3g alternator.

 

[Kevin 007]

Got er going. The stud on the alternator where the battery wire goes was in rough shape due to the melting wire, so i just replaced the original unit with a new one. 78 bucks. A Bosch reman. Left the regulator alone as it is fairly new and i have few spares in the tool box. Made a fusable link with 12 and 14 gauge wire in the fashion that Al suggested. And since i drained the batteries real low last night getting it into a town, shes was a bear to start today after sitting in this weather overnight. Had two vehicles jumping it and still took a while to build up enough of a charge. But I got it home and il need to go thru all the wiring again to double check for any gremlins. Oh and now my factory amp gauge works!! It has never moved before, ever. Anyways, typing on a phone right now so il leave it at that and would like to thank everyone for their quick and helpful replies!