Belt squealing after new alternator

I recently installed a new alternator and serpentine belt on my 1994 Ford F-150 (300ci 6-cyl). My last alternator caught on fire and while I was at that, a new belt seemed to be a good idea.

However, upon finishing the installation of the new parts, there is a terrible squealing that occurs every time I start the motor. It stops after the motor returns to idle rpm.

I notice also that the dashboard meter that measures the alternator charge rises after the squealing stops. It seems like the belt is slipping, but I have dressed the belt several times to no avail.

Any ideas?

With serpentine belt replacement,belt tensioner is usually included.

I have never found “belt dressing” on serp. belts worked.

This is a V-belt technique,curious, what belt dressing product are you using and is there any indication provided to conclude that it (the belt dressing) was intended for serp belts?

I just went through something like this the past week on my Ford. I replaced the alternator, along with the belt and tensioner, and the system would not charge (Battery light on, 11 volts showing, etc.)

The problem was the pulley on the reman alternator. It had been bead blasted and for some reason the surface of the pulley would not bite into the alt. belt.
Most of the pulleys on reman alternators are anodized black and these are not a problem.

To determine if you have a pulley problem here, put a socket on the alt. pulley retaining nut, squeeze the belt a bit tighter with your bare hand, and try to rotate the alternator pulley.
You should not be able to turn it as the belt should lock it down. If it appears to rotate somewhat easily then it’s likely the pulley is at fault.

In my case, returning the alternator and getting one with an anodized pulley solved the problem.