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Alternator not charging at engine start


colinnwn
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In the past 2 months, 3 different times I've had my alternator not work for the first few minutes after starting the car and driving off. I could tell because the battery, and brake light was on, I have a ScanGauge that stayed off (it should turn on automatically), and if I turned it on it showed 11.4 volts. So far this has only happened on the first start of the day, with it fairly cold ~35 degrees.

 

But each time after driving for about 2-3 minutes, before I could get back home, the alternator started working again (the lights went off and the voltage was normal at 14.3 volts.)

 

I'm about to go through the service manual, but has anyone had something like this, or have thoughts on what it could be?

 

The alternator is original, but last year it quit working. I took it to a rebuild shop who replaced the brushes, cleaned it up, tested it, and said it was good. He said it is really rare for a voltage regulator to go, which I was surprised about. The alternator plug is a little tight. I've worried that some day the wires may pull out a little. But if that happens, I think I'd see the alternator be totally intermittent or not work at all.

 

Thanks.

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In the past 2 months, 3 different times I've had my alternator not work for the first few minutes after starting the car and driving off. I could tell because the battery, and brake light was on, I have a ScanGauge that stayed off (it should turn on automatically), and if I turned it on it showed 11.4 volts. So far this has only happened on the first start of the day, with it fairly cold ~35 degrees.
 
But each time after driving for about 2-3 minutes, before I could get back home, the alternator started working again (the lights went off and the voltage was normal at 14.3 volts.)
 
I'm about to go through the service manual, but has anyone had something like this, or have thoughts on what it could be?
 
The alternator is original, but last year it quit working. I took it to a rebuild shop who replaced the brushes, cleaned it up, tested it, and said it was good. He said it is really rare for a voltage regulator to go, which I was surprised about. The alternator plug is a little tight. I've worried that some day the wires may pull out a little. But if that happens, I think I'd see the alternator be totally intermittent or not work at all.
 
Thanks.
Sounds like a failing voltage regulator. He should have replaced it. It's super inexpensive.

Sent from my SAMSUNG-SM-N920A using Tapatalk

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Though the shop did the repair, and I’m not entirely sure where you’re located, did you pull off the Alternator? If so, would you be keen on removing it again? Ideally, I would get that sucker off of there and borrow a ride to a local auto parts store. I used to work at an Advance Auto for a while, and we bench tested the alternators there. Doing that, you’d be able to isolate if it is the alternator that’s the issue, or something with the vehicle. Not exactly a simple job, but if you know what you’re doing to remove and reinstall it, testing the alternator on its own gives you a really good place to start troubleshooting.

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I thought the cheap regulators weren't particularly reliable and you should try to get an OEM regulator which is a good bit more expensive?

I did remove the alternator the last 3 times I've installed a new one. It is a huge bear on the VQs, takes a good 3 hours and lots of laying on your back. It's cold now.

I took my junkyard special that I removed last time to the rebuild shop. It's a Malaysian generic 13900. I figured out after I removed it the real problem was the voltage sensing circuit in my ScanGauge.

I asked him to check the brushes in it, clean it up if necessary, and check it. I'm hoping it will last until I retire the truck.

Wednesday and Thursday will be nice weather. I'll replace it then. I may or may not get the Hitachi alternator tested. It worked fine going over to the shop. I'll be driving the truck until I replace the alternator. So unless the diode ripple is out of spec, it will probably test fine.

If the Hitachi ever goes back on the truck it will get a new voltage regulator.

Sent from my SM-N950U using Tapatalk

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I did remove the alternator the last 3 times I've installed a new one. It is a huge bear on the VQs, takes a good 3 hours and lots of laying on your back. It's cold now.



Oh trust me, I remember! When I tore my engine down recently to rebuild it and freshen it up, the alternator was the biggest pain to reinstall when putting all the pulleys and accessories back on. You’d think for an item that undergoes the stress that it does, it would be a little easier to get to.
I also despise whoever’s idea it was to make the rear nut of the thing removable. I always lost it right as everything would get into place. Ended up using superglue to hold it in place temporarily while I got everything put together.

But yeah, if certainly sucks to do, but getting it off and testing it off of the vehicle is going to give you a better place to hit the ground running.
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