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rlharris
New User
Feb 10, 2009, 6:02 AM
Post #1 of 5
(2631 views)
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altinator problem
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On a 99 Chevy van, with one wire altinater, it keeps dying when the altinater is wired up, but unhook it and it will run all day? why?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 10, 2009, 7:26 AM
Post #2 of 5
(2617 views)
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Re: altinator problem
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You just tweaked my interest as I've had GM "Delphi for example" alts short out - some without being caught in the act leaving battery dead so I just checked the OHMs with an analog ohm meter between body and the main HOT terminal and it registers just a VERY light, low ohm draw - far left of the "infinity" side.
Bet yours would show infinity suggesting it's shorted. OK: It takes some juice to make an alterntor generate current such that a dead battery can't enable an alternator vs way old generators.
You said a ONE wire alternator. You mean by that ONE main wire and a plug which should also be on it for both gauge/light and some if disconnected will disable the alt but not short it.
How can you run all day on no charge? An hour perhaps with a fully charged battery but all day is unheard of to me??
T
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rlharris
New User
Feb 10, 2009, 7:32 AM
Post #3 of 5
(2615 views)
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Re: altinator problem
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Well, yeah, all day is a bit much... Sorry, just about ready to junk the van. Any ideas where I could start looking for where the short? I am out of ideas at this point.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 10, 2009, 7:56 AM
Post #4 of 5
(2607 views)
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Re: altinator problem
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If you touch the main wire to alt and get a substantial spark OR it's not insulated well there the alt is acting as a short and shouldn't.
Diodes inside can do that - usually they just fail and it doesn't charge at all or just slightly but they must be able to short out hard. Just so happens one OE one on a GM of my own did that without provocation and was such a dead short it killed the entire new battery and almost melted off that wire in a couple minutes.
Another was a car that would just be found dead like a light was left on and did that a few times but then charged and went another few weeks and do it again?? Never found anything left on?? Swapped out alternator and it hasn't done it in a year now so by default it must have been able to do just that - but it still charged when running and would test out fine??
I say toss the alt if you are going to fix this at all. You can just get diodes but last time I checked they were too close to the cost of a whole alternator so I didn't go that route.
Side note: When I have one of these with strange problems I take the quesionable parts out if the core is to be returned - those with intermittent problems as they could be reused and cause the same problem when resold as a rebuilt - trust me - they don't use all new parts in a rebuilt. When price is close enough I'm selecting new more often.
Note II: You can fix alternators. Index the body of it and the obvious screws/bolts it will come apart. Bearings, brushes, diode trios can be serviced and then you need to know how to retain the brushes to put it back together - just paper clips really. Will do bearings if just those and they are too common too. If you took it apart you might see something obviously wrong - who knows?
Good luck,
T
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rlharris
New User
Feb 10, 2009, 8:10 AM
Post #5 of 5
(2603 views)
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Re: altinator problem
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Thank you... you may have saved the van.
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