I have a 2007 Pacifica. Recently just started to make some whining noise when the car starts. from the inside it sounds like a bearing problem, but I cant tell if it's coming from a pulley or the alternator.

Can someone suggest a way to test if its a pulley or the alternator bearing makes the sound?

Thanks

 

use a stethoscope

 

lift the belt tensioner with a 3/8 ratchet and remove the belt off the alternator pulley... spin every pulley by hand and see if any have any play... although not a perfect way to diagnose, you will definitely be able to feel grinding or play easily enough... if any grind or move laterally they need to be replaced...

 

I had a similar issue not too long ago, was gonna get a stethoscope to try and find the source, but kept forgetting to get it. coincidentally a few weeks later my alternator died on the highway at 2am. had it towed home, replaced alternator, whining is gone. Also it doesn't hard shift in between 2nd-3rd gear anymore.

 

ringing indicates dry/hardened grease or damaged races/bearings... if you are extremely careful, you can likely remove the pulley and 'service' the bearing, replace the bearing or easiest yet is to buy a new pulley. When I thought my alt pulley was out (even using a stethoscope) it ended up that my idler pulley was the culprit. I experimented with replacing the bearing, servicing the bearing and replacing the whole pulley as I did the lower idler and tensioner bearings also. All of the above are similar solutions depending on skill and resources/time. You will be amazed if you check the grease hardening - it may look/feel like plastic!