Alternator Dying?
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Senior Member
Joined: Dec 2012
Posts: 401
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Alternator Dying?
Hi Everyone,
I just started hearing a whining noise under the hood (loud enough to hear in the cab while idling and driving at low speed). When looking under the hood, it should like it's coming from the alternator (could also be the vacuum pump). I made the 3G upgrade about five and a half years ago with the RJM Injection kit. I have a real voltmeter installed and the alternator appears to be giving the correct voltage. Could this be the bearings starting to go out? Is there a way to test? Also, is there a way to test to see if it's the vacuum pump, which is still drawing vacuum?
If the whine is coming from the alternator, should I replace it, or can just the bearings be replaced? Also, any recommendations on a new 3G alternator? RJM Injection doesn't appear to be in business any more and my order didn't specify the brand/model fo the alternator that was included in the upgrade kit and the box is long gone. I was looking through old posts about the 3G swap and was thinking about using this one if I need to replace it (https://www.autozone.com/batteries-s...d43737-8-11065)
Thanks!
Thanks!
I just started hearing a whining noise under the hood (loud enough to hear in the cab while idling and driving at low speed). When looking under the hood, it should like it's coming from the alternator (could also be the vacuum pump). I made the 3G upgrade about five and a half years ago with the RJM Injection kit. I have a real voltmeter installed and the alternator appears to be giving the correct voltage. Could this be the bearings starting to go out? Is there a way to test? Also, is there a way to test to see if it's the vacuum pump, which is still drawing vacuum?
If the whine is coming from the alternator, should I replace it, or can just the bearings be replaced? Also, any recommendations on a new 3G alternator? RJM Injection doesn't appear to be in business any more and my order didn't specify the brand/model fo the alternator that was included in the upgrade kit and the box is long gone. I was looking through old posts about the 3G swap and was thinking about using this one if I need to replace it (https://www.autozone.com/batteries-s...d43737-8-11065)
Thanks!
Thanks!
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
To check the bearings withOUT a mechanic's stethoscope (which is inexpensive & very useful), slip the belt off & spin the alt as fast as you can (tools are OK if you don't damage the alt pulley). Then listen as it spins down - it should not rumble or whine. It should not stop suddenly - it should spin more slowly until it's barely moving before stopping.
Stay OUT of the zone. The best 3G is a factory-original from the JY. They rarely fail, and vehicles are rarely junked because of a bad alt. So you can safely assume that most JY alternators still work.
(phone app link)
If you've never rebuilt an alt, it's not worth learning for just one. It's easy to change the VR, but it sounds like that's NOT your problem.
(phone app link)
Stay OUT of the zone. The best 3G is a factory-original from the JY. They rarely fail, and vehicles are rarely junked because of a bad alt. So you can safely assume that most JY alternators still work.
(phone app link)
If you've never rebuilt an alt, it's not worth learning for just one. It's easy to change the VR, but it sounds like that's NOT your problem.
(phone app link)