Hi,
About one month ago, I started hearing a sound from under the hood like metallic birds chirping. The intensity increased with acceleration or raised idle. All remained steady (but a bit noisy) until a few hours later. The sound got a bit louder and more persistent and I noticed that at stop lights with accessories on, the lights would dim and the idle would drop unless I put it neutral and raised the idle a bit until I took off agin. My aftermarket voltmeter looked normal when driving but went into the red at stop lights (with accessories on). For the last month, at lights I have to shift into neutral and raise the idle a bit to keep it from cutting off or having voltage drop way into the red. It is always green while driving now and almost always red with lowish idle at stop lights with accessories on.
A local mechanic told me the noise was my tensioner but that my alternator (2 months old) was also bad.
I am at another mechanic today to change the alternator and he says my alternator is fine. He is changing the hydraulic belt tensioner but says the alternator would not cause these exact symptoms.

Is this issue my alternator? If not, What else could it be?

 

could be the tensioner if there is not enough tension on the belt the alternator pulley and other pulleys will slip some and not give you a full output. I would start with the part that is making the noise if the tensioner is shot and/or out of the tick marks on the side then start with that, sounds like the alternator is probably working if the car is generally staying on, if it was going bad it would get worse and leave you stranded when the battery drains.

 

Thanks Ali,
We replaced the tensioner yesterday but the pulley on the alternator is a millimeter or two out of line with the other pulleys. On the way home, it chewed a mm or so off the edge of the belt. Hopefully I can make it back to him without the belt breaking.
I noticed yesterday that at stop lights, my aftermarket volt meter goes into the red and displays as low as 10v with accessories on at a full stop. It goes back up to 13-14v after we start rolling again.
Is the 10-11v reading while stopped a problem?

 

well I dont have one of those but 10v does not sounds very good. could be the alternator haven't had this problem.

 

I just had this problem happen in my brothers cr-v.
the culprit... the tensior was not providing tension on the belt.
but the chripping sound... that's a bearing going out.
I would see if you could rotate the alternator pulley by hand.
the ac clutch by hand. (the ac clutch was the culprit in my brothers case so we took it out and used an ac bypass pulley)
if they don't turn freely, or hear a noise while spinning them, they are shot.

 

I went back to him today. He changed the alternator a third time because the pulley was a MM or so out of line with the other pulleys. He used a different brand, all lined up well and we replaced the belt again as well. The belt spins smoothly, the noises are gone, and the volt meter reads higher now.
The volt meter still goes down to 11-12 when stopped which is Red on the meter, but it is higher than it was. This may be related to idle. When I put the AC on, the idle goes up a bit and the problem goes away. Could it be that idle control thingie?
Thank You Ali.


It may have been the tensioner because after we changed the belt, the tensioner and the alternator, the sound is finally gone. The voltage is still a bit low but it is better.
Thank You for your help.