Alternator whine - but its not the usual suspects....

[Jimxms]

I've been chasing down an annoying whine on my (new to me) 07 Escalade for about a month now. The whine is 100% alternator related, as if I disconnect the + cable from the back of the alternator, the whine goes away. The alternator also seems to be under stress as I noticed a fair amount of belt rubber on the alternator after only a 100 miles of driving.

I've tried:

* 3x new alternators (AcDelco, WAI)
* A new belt
* A new battery (also bench tested the old battery)
* NO battery (disconnected the battery while the car was running)
* Cleaning the battery terminals & connectors with sand paper
* Cleaning the fusible link and connectors with sand paper
* Cleaning the negative cable that runs from the battery to the engine block passenger side
* Cleaning the negative cable that runs from the back of the engine block to the firewall drivers side.


While narrowing it down to the alternator, I also replaced these so they can be 100% ruled out as culprits:

* Idler pulley
* Tensioners (main and AC)
* Water pump
* Power steering pump

The car has no aftermarket audio or other power consuming devices. The alternators have all been 145A rated.


The car starts, runs and drives 100% fine.

 

[Fless]

Post a pic or video of the main serp belt tensioner, so we can see where the marks land.

What model number belt are you using for the main belt?

What make and part number for the alternator that's on it in the new pic or video with the tensioner?