2005 Chevy Trailblazer Engine Whine?

Dave1 · March 14, 2009

The in line six cylinder engine in our 2005 Chevy Trailblazer LT with 55,000 miles now has a louder than usual engine whine noise. The whine noise speeds up with RPM and sounds like it is coming from the alternator or idler pulley right below the alternator. I am guessing the noise is coming from the alternator. You can hear the whine increase/decrease with engine speed as you drive along.

The dash gauge shows a normal 13-14 volts of charging, but never drops below that.

Is there any history of alternator failure at that mileage?

Could a battery that is going bad cause a constant charge situation and the loud alternator whine? The engine starts fine, no starter drag, etc. like the battery was low on voltage.

Thanks for any info, Dave

superjim · March 14, 2009

Is there any way that you can use a piece of heater hose to stick down there to each component and touch them whils holding the other end to your ear...SAFELY...without getting it caught in the belts or other moving components?

The heater hose will act as a stethoscope, and let you pinpoint exactly where the noise is coming from.

An alternative is to take the belt off and spin the idler pulley by hand to check for any roughness in the bearings.

Operation Mindcrime · April 10, 2009

Replace the idler pulley below the alternator, from Gm it comes as pulley and bracket. You can just remove the pulley and replace it. I'm not sure if the pulley is available seperately in the aftermarket yet. It should sound like a power steering whine.