Burning through 3g alternators
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Senior User
Joined: Oct 2015
Posts: 445
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From: Bismarck, ND
Burning through 3g alternators
Been having rough encounters with my 3g alternators lately,one was remanded and this one was new, I've burned through two 3gs this summer with them slowly dying a painful death (for me) had to drive home in the slight dark with no taillights and very dim headlights today. Has anyone seen an issue with their alternators failing? Could it be heat from the engine block?(just naming possibilities) or my slight oil leak from my valve covers? Or am I just getting unlucky?
I am using wire taken from the donor 3g car with a new battery early this summer, clean grounds also.
Should I cut my losses and buy the 1g alternator oreillys has on hand or wait a few days for another 3g?
I am using wire taken from the donor 3g car with a new battery early this summer, clean grounds also.
Should I cut my losses and buy the 1g alternator oreillys has on hand or wait a few days for another 3g?
Senior User
Joined: Feb 2015
Posts: 294
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I've seen information that poor grounds cause extra heat to build in the alternator causing premature failures. There's no way your truck subjects it to more heat than the taurus it came from. Make sure you have good battery to block, and block to alternator grounds. If the block or mounts are painted, you may need a ground from the alt itself.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
I wouldn't downgrade to a 1G
Here's some tests to run .. voltage drop is a good one, and easy.. Let us know what you find!
http://www.aa1car.com/library/charging_checks.htm
Here's some tests to run .. voltage drop is a good one, and easy.. Let us know what you find!
http://www.aa1car.com/library/charging_checks.htm
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Where did you pull the ignition hot wire from? By chance did you leave the shunt wiring in place? Where is your voltage sensing wire connected to? Answer those and we can solve this. The 3g is such a simple alternator this situation can be fixed. Also is the battery of good condition?
Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
Do you have one or two grooves on the alternator pulley? When I first put my 3G on a few years ago, I only had one V-belt groove on the alternator and had some problems with belt slippage and the alternator getting hot really quick.
I installed a two groove alternator pulley and two belts. This stopped the slippage.
I installed a two groove alternator pulley and two belts. This stopped the slippage.
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Senior User
Joined: Oct 2015
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From: Bismarck, ND
Do you have one or two grooves on the alternator pulley? When I first put my 3G on a few years ago, I only had one V-belt groove on the alternator and had some problems with belt slippage and the alternator getting hot really quick.
I installed a two groove alternator pulley and two belts. This stopped the slippage.
I installed a two groove alternator pulley and two belts. This stopped the slippage.
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Lead Driver
Joined: Jul 2011
Posts: 8,679
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From: On the Edge of the Desert
i think its probably a ground problem as well. or something else not right with the wiring.
dual belts are reccomended, but a single belt works ok so long as you keep it tight.
dual belts are reccomended, but a single belt works ok so long as you keep it tight.
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Thread Starter
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Senior User
Joined: Oct 2015
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From: Bismarck, ND
I also had the truck completely die at once with no electrical last friday
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
Are you sure the alternator is wired correctly? If the wires are wrong then the regulator/diodes will be energized at all times. Thus draining the battery and burning up the alternator.
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Senior User
Joined: Oct 2015
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From: Bismarck, ND
When I first installed this one I had the "exciter" hooked up to a 12v switch so that probably killed it 90% before I noticed and changed the wiring
Fleet Mechanic
Joined: May 2001
Posts: 1,396
Likes: 4
From: Cupertino
Do two things:
1) When on fast idle, put the multimeter on a low voltage dc scale and read the voltage between the alternator case and the battery negative terminal. The correct answer is less than .1 volt. This checks for a bad ground.
2) Do a voltage check at the battery terminals on fast idle. The correct answer is in the low 14s.
Anything else, come on back in.
1) When on fast idle, put the multimeter on a low voltage dc scale and read the voltage between the alternator case and the battery negative terminal. The correct answer is less than .1 volt. This checks for a bad ground.
2) Do a voltage check at the battery terminals on fast idle. The correct answer is in the low 14s.
Anything else, come on back in.
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Senior User
Joined: Oct 2015
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From: Bismarck, ND
Apologize for the late response, schooling and work got in my way of working and logging on here, when I checked my battery voltage after charging it to full, letting it idle the voltage would drop from 12.9 to about 12.06 by the time I shut it off, it was a slow drain and over time it'd die on me.
Fast forward to now, I got alternator (brand new this time, knew the guy at the counter and he warrantied my remand for a new one) and it cost be 14 dollars! Went through and installed this new alternator and now I get 14.2 volts steady at idle!
Fast forward to now, I got alternator (brand new this time, knew the guy at the counter and he warrantied my remand for a new one) and it cost be 14 dollars! Went through and installed this new alternator and now I get 14.2 volts steady at idle!
Logistics Pro
Joined: Aug 2015
Posts: 4,093
Likes: 14
From: Lind, WA- Eastern WA
Apologize for the late response, schooling and work got in my way of working and logging on here, when I checked my battery voltage after charging it to full, letting it idle the voltage would drop from 12.9 to about 12.06 by the time I shut it off, it was a slow drain and over time it'd die on me.
Fast forward to now, I got alternator (brand new this time, knew the guy at the counter and he warrantied my remand for a new one) and it cost be 14 dollars! Went through and installed this new alternator and now I get 14.2 volts steady at idle!
Fast forward to now, I got alternator (brand new this time, knew the guy at the counter and he warrantied my remand for a new one) and it cost be 14 dollars! Went through and installed this new alternator and now I get 14.2 volts steady at idle!
Post Fiend
Joined: Jun 2003
Posts: 8,209
Likes: 12
From: Black Hills of SD
I pay 10 bucks for used 3gs at the junkyard and have never had one fail. I think you better do like Couger John said and do some voltage drop tests to check for bad grounds/connections.