# Engine compartment noise



## tomgrancher (Aug 10, 2009)

I am writing on behalf of my brother who owns a 2006 GTO. He has had this engine compartment noise for several months, which, by my estimation, sounds like a bearing noise. The dealer replaced the alternator last month, after which time the noise went away but returned within a few days. He brought the car back to the dealer, and know they claim that the alternator was making the noise because of the heavy duty battery he installed some time ago. Although I have never heard of such a thing, is that possible? Could it be the idler pulley (that's what we used to call the belt tensioner back in the day)? He is leaving the state for a while and I thought it might be a nice thing to get it fixed while he is away.
Thanks in advance for all replies.
Tom


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## GTO JUDGE (May 14, 2005)

They are stating the noise is a result of a heavy duty battery causing noise to an alternator? IMMEDIATELY, take the car elsewhere. Sounds like a bearing? Have you listened carefully to the AC compressor? The belt tenrioner would emit a squeaky noise not a bad bearing noise. You ought to zero in on the noise by sticking your ear to the noisy area. If it is a pulley etc and you can narrow the noise down, try squirting a little bit of teflon spray on the noisy area. If the noise stops then you know where its at. If the noise is internal no exterior lube will help it. 

If you cannot identify the exact location of the noise: Place a long handled screw driver or pry bar on different areas while the engine is running WITHOUT getting the screw driver near the fan belt, and place your ear on the end. The noise will magnify through the handle. If its a bearing it will be screaming at you.

To blame a battery shows ineptness and I would not chance this type "tech" checking my oil level. Why would they replace a good alternator in the first place if its a heavy duty battery? I'd love to see that diagnosis in writing. :willy:


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