Possible Alternator Problem?

[bill1013]

Aloha Everyone! I'm writing in hopes of getting a few possible answers or fixes to a very weird problem. Here goes, I got a new battery about 5 months ago and it has kept my alt meter at above 12 o'clock ever since I bought it. I get in and start my baby up and it stands more than *****. But as I drive it slowly goes down to around the 10 o'clock position and stays there for the entire drive. I turn her off then start her back up and the needle stands straight up. This only happens during daylight hours. When I drive at night the alt meter stays exactly where it was when I started her up. And that's with all the lights and accessories going full blast! During the day, with nothing on except the radio, the alt meter shows a slight drain. Which, to me is weird, as during the daytime running there really isn't a drain, but at night, when you expect a slight drain...there's nothing. Not the slightest drain whatsoever. The only thing I could come up with is maybe the serpentine belt is slipping during the heat of the day. Hot expand...cold retract. Sounds crazy I know. What's even crazier is my dealer says it's the alternator. And he said that over the phone without even doing any diagnostics! I'm really hesitant to give my baby to him and then have him charge me an arm & a leg when it can be just a lose/worn belt. Also, the belt is really tight as far as I can tell, but I know the tensioner could be slightly off and that might be what's causing it. Any ideas before I try to remedy this on my own? Appreciate any insight, troubleshooting or repair thoughts. Mahalo for the advice in advance. May the Force Be With You!

 

[89Suburban]

Look at this thread and see if it answers your question:

Voltage dropping after driving

Something I noticed in the past few days is when I start the engine, the voltage gauge will be above 14 and it will stay there for 10-15min but eventually drop suddenly to around 12. It seems to stay there until I restart and then it’s back above 14. Is this normal? I’ve never seen a vehicle...

www.tahoeyukonforum.com

 

[bill1013]

NEWS FLASH! PROBLEM SOLVED!!!!

Just got my baby back from the dealer and it was the alternator after all. When I described that the drain on the battery only happened in the daylight hours, not at night, Lou, the mechanic looked at me and said, "You're effing with me right? Either that or it's haunted!!!" Anyway, he did a full diagnostic check. Battery good, voltage regulator good, charging system good, alternator good...Wait alternator good? After letting it idle for around fifteen minutes he looked at it again, but it was still putting out the required volts & amps, although he did notice and slight humming coming from the alternator. The tune wasn't familiar, but it was definitely a hum. The hum turned into a low clicking noise so he turns off the truck and removes the alternator. After he gets it off he noticed that one of the armatures inside is completely broken off and the bearing in the back was cracked. He put a new alternator on and my baby is her old self again.

We still couldn't figure out why it was good at night but drew heavy volts during the day. Also why didn't their diagnostic equipment didn't pick up the problem. Sure it was a physical problem, but a broken armature can't be putting out the same power as a good one. We came to one, seeming sexist conclusion, my baby is a possessed *****! But I love her just the same! 127K miles and still going strong!

 

[tom3]

Sometimes it's kind of amazing that with all the super high technoloy in these vehicles that the problem is a cracked hose, dirt, loose or broken part, etc. Also good that you found a guy who took the time to really get it sorted out.