2003 Mustang V6, Pulley Problem

Chris Peterson

New Member
Mar 11, 2012
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Hi, I have a 2003 Mustang V6. Whenever I get to about 4k RPM's their is this sound in the belt/pulley system that sounds very bad, it makes a grinding/slip noise and I would really appreciate it if someone could tell me what it is.

Here is a link to the video I made of it:

Thanks, Chris
 
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Sounds like the alternator surging. Perhaps because the belt tensioner is weak. Or perhaps because the alternator bearings are going out.

When the motor is quickly reved up and down, this is going to make the acc surge. Does it do it while the motor is under load?
 
When we took it to a mechanic a couple of weeks ago he said something about the bearings to. But I haven't gotten the entire thing checked and fixed yet, hopefully this week.

But to answer your question, It still doest it no matter what it is, If im accelerating on takeoff; or going 40 and then punching it. It will still make the noise.
 
Another quick test is to remove the serpentine belt and then run the engine briefly, if the noise goes away, then the noise would be caused by one of the items that the belt is spinning. While the belt is off, and the engine is off, you can spin the alternator by hand as well as the water pump, idler and tensioner pulleys ect and see if any of them does not feel smooth or make any noise. A long screwdriver can also be used as a poor man stethoscope to help pinpoint the source of the noise.
 
Sounds like one of the bearings is squealing only on deceleration. If you can't tell where it's coming from by ear, take anything long that's made of metal and touch one end to your ear and the other end to each bearing as a friend blips the throttle. Be VERY careful not to get it in the belt.

I bet pretty soon the bearing in question will start squealing all the time, and at least that will make it easier to find.
 
Sounds like one of the bearings is squealing only on deceleration. If you can't tell where it's coming from by ear, take anything long that's made of metal and touch one end to your ear and the other end to each bearing as a friend blips the throttle. Be VERY careful not to get it in the belt.

I bet pretty soon the bearing in question will start squealing all the time, and at least that will make it easier to find.