kcd1184 Posted March 29, 2005 Report Share Posted March 29, 2005 Had my alternator rebuilt last fall. Did removal and installation myself. Worked fine, but I thought there was a high pitched hum coming from it. Told the guys that rebuilt it that I was parking it for the winter and they said no problem, whenever you decide to pull it again, we'll check it out. Pulled it out the other day and took it to the rebuild shop. They threw it on a high tech machine and it was cranking 180 amps.There was a small noise, but not the one I kept hearing. They tore it apart and could'nt find anything wrong other than hot spots on the brush rings. They cleaned the brushes, and changed the bearings. They said that putting the noise aside, that I probably needed to see if I had a short that was constantly making the alternator run, and to check my battery. Well, I had just put a big new Interstate battery in when I did the rebuild the first time, but I took it to check it out and it had a bad cell. Got a new replacement battery and reinstalled the works. Noise is still there but I've decided it is coming from underneath somewhere, but if I hadn't pulled the alternator the second time I might not have found the battery problem in time to save the rebuilt from burning up. That stupid noise never changes pitch except when you come to a stop, and then there is just a little surge down and then right back up. Kent Link to comment Share on other sites More sharing options...
Scotty Posted March 29, 2005 Report Share Posted March 29, 2005 Kent, I had the same problem. I wish that you posted this before you pulled your alternator. I had a whine and the SHOP could not find it and basically told me I was wacked. I swore it had a whine. Well, I bought american made front and rear bearings (SKF) pulled the alternator and said, do me a favor, replace the bearings with my bearings and give it back to me, they charged me $20... Result, WHINE GONE! The same rebuilding shop had rebuilt it about 2 years prior. The front bearing was made in CHINA (YUK). If I rolled it in my fingers it would occasionally jam/bind up, there was either dirt, a rough spot or a flat spot in the bearing. Mike Link to comment Share on other sites More sharing options...
Barry94 Posted March 29, 2005 Report Share Posted March 29, 2005 Did you start the engine without the belt installed ? If so, did you still hear the noise. ? If not, then it's likely one of the two belt idler bearings, the power steering pump or the AC pulley bearing. Barry 2008 STS V82016 Colorado Z711970 Corvette LT-1 Coupe Link to comment Share on other sites More sharing options...
STYES Posted March 31, 2005 Report Share Posted March 31, 2005 Typical stock alternators AND ac compressors on NS cars make noise. Had them both replaced under warrantee on my car. They still make noise. This is not an excuse or a panacea for your problems, just a fact that I've seen many times. Link to comment Share on other sites More sharing options...
maydog Posted March 31, 2005 Report Share Posted March 31, 2005 If you hear the noise with the alt in the car next time, you may want to try a mechanics stethescope to pinpoint the source to be sure it is the alternator. Link to comment Share on other sites More sharing options...
JoeM Posted March 31, 2005 Report Share Posted March 31, 2005 Is there any way to test an alternator other than taking it to a shop to see how many amps it is putting out/is in spec? Link to comment Share on other sites More sharing options...
davedog Posted March 31, 2005 Report Share Posted March 31, 2005 I had a slight hun similar to what you described when I first bought my 92 eldo, turned out to be the water pump....replaced it, no more whine Crystal Red Tintcoat Exterior | Shale/Brownstone Interior | 32k Link to comment Share on other sites More sharing options...
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