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Alternator Short Help!


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QualiT23
Novice

Mar 21, 2017, 12:12 PM

Post #1 of 13 (357 views)
Alternator Short Help! Sign In

Hey guys. I did something stupid... I had the alternator off to check a pulley. I started up the truck, and the alternator vibrated back because I didn't retighten it. The terminal on the back of the alternator then touched the engine block, sparked, and everything went dead. Im curious if anyone has advice as to what would have blown? Battery still works fine, I've double checked all the fuses under the dash, and they are fine. Starter works if I arc the terminals together. My truck is a 1980 chevy silverado (K20) with a 350. Any help would be much appreciated. thanks.


Discretesignals
Ultimate Carjunky / Moderator
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Mar 21, 2017, 12:56 PM

Post #2 of 13 (349 views)
Re: Alternator Short Help! Sign In

Check your fusible links.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 21, 2017, 12:57 PM)


QualiT23
Novice

Mar 21, 2017, 1:25 PM

Post #3 of 13 (338 views)
Re: Alternator Short Help! Sign In

I checked the one with an ohm meter by the starter, and the other one was up on the driver side of the truck. Both are good. Are there more than two on the old square body trucks?


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 21, 2017, 2:04 PM

Post #4 of 13 (330 views)
Re: Alternator Short Help! Sign In

Interesting and surely a problem. Just maybe the alternator itself is a strong short and hasn't blown a fusible link but rather draws away excessive current inside itself.


Just as a test for unusual try disconnecting the eyelet end and assertively isolate it from grounding. See if all comes back and if so alternator is shorted inside which may only do that when turning or still? Why? A sudden surge to charge beyond it's capability burnt inside,


T



kev2
Veteran
kev2 profile image

Mar 21, 2017, 3:35 PM

Post #5 of 13 (316 views)
Re: Alternator Short Help! Sign In

alt has 3 wires - the 2 red wires should have 12v - yes no?
fusible link from batt to alt.


QualiT23
Novice

Mar 21, 2017, 5:42 PM

Post #6 of 13 (302 views)
Re: Alternator Short Help! Sign In

Ok, we got it! Luckily, an old timer I ran into at the post office had nothing better to do than mess around with my truck. It turned out to be the positive line from the battery to the alternator. Coincidentally, it was fried and pretty much dust inside when we cut it open. This last jolt must have been all it needed to finish it off. He couldn't believe it blew before the fusible links did. Anyway, I appreciate the quick response from everyone! First time on this site, and certainly won't be my last. Thanks.


Hammer Time
Ultimate Carjunky / Moderator
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Mar 21, 2017, 6:17 PM

Post #7 of 13 (298 views)
Re: Alternator Short Help! Sign In

That wire IS a fusible link. You cannot simply replace that with regular wire. It have to be repaired with fuse wire.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 21, 2017, 10:24 PM

Post #8 of 13 (288 views)
Re: Alternator Short Help! Sign In

? I thought you said that wire showed it was good? As HT just said and don't wait, replace that with "fusible link" wire of same rating. It's sold and marked at auto parts outlets + marked again on the wire very small what it is. It's meant to fry just more usually all wrinkled and obvious,


T



Hammer Time
Ultimate Carjunky / Moderator
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Mar 22, 2017, 2:24 AM

Post #9 of 13 (282 views)
Re: Alternator Short Help! Sign In

You won't use fuse wire on the entire length of the wire, just the section that is already fuse wire. You should see a separation there to identify where the link stops and regular wire starts.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



QualiT23
Novice

Mar 22, 2017, 5:33 AM

Post #10 of 13 (266 views)
Re: Alternator Short Help! Sign In

Let me be a bit more clear on how little I know of this. I saw the fusible link and assumed the connecting piece where one wire splits into two was the actual fuse, not the wire itself. I checked the wire on each side of the splitter, it was good, so I assumed the wire was good. I went back to the comment section on a youtube video where I watched that, and they lit let the guy on fire for explaining it wrong. I should have read that first. But hey, I wouldn't have stumbled onto this site if I had!


QualiT23
Novice

Mar 22, 2017, 5:34 AM

Post #11 of 13 (264 views)
Re: Alternator Short Help! Sign In

Hammer time, we did use a fusible wire. We did, however, replace the entire length.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 22, 2017, 5:42 AM

Post #12 of 13 (260 views)
Re: Alternator Short Help! Sign In

As HT said, just use the length that burned up even unseen and inside it would all be crunchy. It's color coded and rated like fuses are so use only the correct stuff. Do solder it in and shrink wrap over splice.
It's supposed to blow when something goes wrong or horrors worse than you had happen would happen. IDK - sold as you found new stuff in a blister pack or off a roll just make sure of right length and rating to blow otherwise it's just wire looking,


T



Hammer Time
Ultimate Carjunky / Moderator
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Mar 22, 2017, 7:03 AM

Post #13 of 13 (251 views)
Re: Alternator Short Help! Sign In

You can't do that. The length of the fuse wire varies the amperage rating. You need to use the same length of fuse wire that it came with, usually only a few inches.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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