Help me figure out if my alternator is bad.
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Joined: Oct 2016
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Help me figure out if my alternator is bad.
1990 firebird 5.7l tpi 350
Truck died in an Orielly auto parts parking lot,
- got a jump, drove it around the block to charge
- came back to the parking lot and turned the engine off and it died again
- got another jump and the alternator tested by store rep
..She said the alternator isn't charging the battery.
How do I figure out if the wires are bad or the alternator is bad?
Should I just buy an alternator and see what happens?
I think it could be the wiring because this 5.7l was swapped into my truck by the previous owner and I have to say the wiring looks like poo.
I cant afford a new motor right now but I need to drive the truck around the garage so I can do body work and paint first, so i just need the cheapest decent solution.
Truck died in an Orielly auto parts parking lot,
- got a jump, drove it around the block to charge
- came back to the parking lot and turned the engine off and it died again
- got another jump and the alternator tested by store rep
..She said the alternator isn't charging the battery.
How do I figure out if the wires are bad or the alternator is bad?
Should I just buy an alternator and see what happens?
I think it could be the wiring because this 5.7l was swapped into my truck by the previous owner and I have to say the wiring looks like poo.
I cant afford a new motor right now but I need to drive the truck around the garage so I can do body work and paint first, so i just need the cheapest decent solution.
Joined: Oct 2001
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From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: Help me figure out if my alternator is bad.
If it's not putting out 14.4 volt or so, its bad and will need replaced. If battery fails a load test its also bad.
Joined: Jul 2011
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From: Davison, MI
Car: 89 Camaro
Engine: Dart SHP 400-Holley Terminator EFI
Transmission: Tremec T56 Magnum F
Axle/Gears: Strange S60 3.55:1
Re: Help me figure out if my alternator is bad.
A bad battery will make a good alternator look bad. Charge and test your battery first.
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Re: Help me figure out if my alternator is bad.
my battery is fine its new. My alternator has been on the car before i bought it, BUT how do i know its not something else that's causing the alternator to not work properly.
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Joined: Nov 2016
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From: North Carolina
Car: 83 Z28 / 89 IROC
Engine: 350's
Transmission: T5 WC / 700R4
Axle/Gears: Posi 3.73
Re: Help me figure out if my alternator is bad.
You can crank it again and disconnect the battery. If the alternator is working it will keep running. But not a 100% test that its putting out the correct voltage or something else draining it.
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Car: 1992 TA Convertible
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Re: Help me figure out if my alternator is bad.
Take the battery and the alternator out and get them bench tested. Autozone will do it for free, i assume O'rielly's will also. Dont buy new parts just to test them. If they test good, reinstall and check all the wiring and connections. The charging system is as good as it's weakest link.You say the wiring looks like "poo". Even if you do find a bad alternator or battery, you may not be fixing the real problem. Corroded wires or bad connections cause resistance that makes the battery and alternator overwork to compensate and shortens their life.
Thread Starter
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Joined: Oct 2016
Posts: 104
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Re: Help me figure out if my alternator is bad.
Take the battery and the alternator out and get them bench tested. Autozone will do it for free, i assume O'rielly's will also. Dont buy new parts just to test them. If they test good, reinstall and check all the wiring and connections. The charging system is as good as it's weakest link.You say the wiring looks like "poo". Even if you do find a bad alternator or battery, you may not be fixing the real problem. Corroded wires or bad connections cause resistance that makes the battery and alternator overwork to compensate and shortens their life.
thanks i will take them out and have them bench tested.
as for checking the wires, i can do a visual inspection but if the problem was "not visible" how would i be able to test it?
ive got a mutli meter.