I just had the alternator rebuilt last year. I took an extra section of oil cooler hose and listened to where it was coming from. It could have been the idler pulley or the alternator pulley bearings, but it seems like it might be coming from the inside, maybe the metal fan blades?? Has anyone else ever had this problem? The sound is a pretty distinct, loud consistent rapping sound, like the edge of one metal piece striking another. If it was a bearing, wouldn't it sound more like a low pitched grinding sound? Thanks for any help you guys!

 

There are no fan blades inside the alternator. Maybe you are thinking of the rotor that has somewhat of a strange shape. But as to exactly is making the noise, that is hard to say. Bearings usually make a squealing sound. But if a bearing has self destructed, it could allow the rotor assembly to be out of alignment inside the alternator and hitting something, such as the stator.

Remove the drive belt and turn the alternator pulley by hand. Try wiggling the pulley side to side, try pushing/pulling the pull in and out. If you can detect any movement, thare is a problem. If the pulley does not turn smoothly, there is a problem.

 

Bad pulley bearings can tick, especially the tensioner.

Dennis has it, just spin each one by hand. You'll be able to feel the culprit.

 

Goddamn it. I REALLY can do without the pain and frustration of taking off the Alternator AGAIN!! It was hard enough in the winter, now I have to do it in this crazy hot heat.

 

Are you confirming alt bearings? I was hoping it was idler pulley. That's what mine was, on a F*cking 2014 motor.

 

Yeah, well I have no idea if it is the alternator bearings or not. Now I DO KNOW that it's not charging the battery at all. Voltage read 12.03 volts with engine off, when we started it, voltage dropped to 11.90 volts. Also, the casing has a very prominent dark black spot on it by the pulley. Something got fried in there for sure. I don't know how that could have happened since the car has not been driven more than 15 miles since last year in January....WTF???!!

 

The shop that rebuilt it tested the alt and it was pitting out 14.1 Volts. He said the black spots are probably belt dust. DeathZone and O'Really? Auto parts put it on their testing machines and it failed according to them, but I'm calling shenanigans. They probably just wanted to sell me a new one. Anyone else had this experience?

 

The chumps that work at DeathZone and O'Really's could care less what they sell. They make eight bucks an hour either way. My concern would lie within their competence to operate idiot-proof testing equipment without hitting up their Facebook sub-chump friends in the back of the store first. And fire your rebuild shop. 14.1 is unacceptable. Get a DMM and do some basic driveway testing of your own. It will tell you what you need to know. I'm running a $45 dollar wallyworld battery that came with my car and rested well at 12.6 before my swap 10k mi ago. It now rests at 12.45 and I have a $750 dollar 270 amp alternator that charges at 14.8 all day long. Anxiously awaiting my 120ah worth of Lithium batteries from China to delete the under-hood battery and get this car some proper voltage. New battery and a NOS sticker I'm thinking will yield at least 40hp on the top end.

 

Thanks user1, I just decided to buy a new one and be done with it. It's not worth the mental anguish anymore, especially since I'm now selling it to a close friend.

 

Well if it was rebuilt correctly using the cadium plated hardware and component internals then it would be fine! Here's the real truth to local shops that rebuild starters and alternators most disassemble the units and bead blast the alternator casing, hardware, etc! Then install new bearings if that, solder in an aftermarket internal regulator (if that) and reassemble, test and that's it! I noticed years ago these starters and alternators found mostly at your local auto part store with the dull finished casting and a few months later maybe a year you're replacing it again! The weather is the factor that kills most due to all the protective coatings on the hardware etc. being removed during the bead blasting process and reassembled with the same unprotected hardware and the damn things just stop working! The cadium plated is there is ensure no corrosion and therefore a factory rebuild unit will last for years and these cheaply rebuild turnaround units are destined for failure! You can look at a starter or alternator if you see the goldish brown tinted hardware and a coated aluminum that's kind of dark or semi shiny like clear coat is a protective etch! If the hardware isn't exhibiting that goldish brown tint and it's silvery like as well as a dull finished aluminum casing! That hardware is unprotected and you unit will live a short life!