Alternator Belt - Wrong way up!

[Jay]

OK, I changed my belt about a month ago (maybe 2), I checked it after a few days, then 2 weeks and tightened as needed.

Now I popped the bonnet yesterday to check fluid levels and all that and noticed the belt was inverted, ie the teeth pointing upwards  So I took it off, checked for damaged, it seemed fine. Popped it back on. Been moving house today so done about 60 miles since correcting the alternator belt, rechecked it a little while ago and again the belt is inverted, the car runs fine and no problems with the electrics.

Is it just a faulty belt or have I done something to cause this?
Would giving the alternator pulley's a rub down with sand paper to roughen it up a bit help?

[Benrevs]

Check the pulleys are straight and the edges are not bent in, this happened to me before..

[rubjonny]

how far in the groove does the belt sit, perhaps its a smidgeon too thick?

[Jay]

Good point Johnny, I'll have a look when I'm home, I can't remember what it looked like while sitting in the groove.


Is there an easy way to test if the pulleys are all aligned correctly?

[rubjonny]

run the engine and look at the belt, should be obvious if its not straight!
if it all looks ok, whip the belt off and check the alternator & waterpump pulleys spin free, if they're tight/rough could explain it?

[Jay]

Right didn't look at it because the car failed it's MOT badly.

[sidecarphil]

oops

listy list 

[rodz22]

use a ruler and put it flat on of the pulleys
if it doesnt sit on th other pulley bingo

think thats how you do it

cant think now but check your alternator mounting bushes see if they are cocked ?
 

[Bcarm]

As rodz22 says use a straight edge like a ruler, it should sit flat against the edges of the pulleys you are checking for alignment.  Also make sure that the inner surfaces of the 'v' in the pulley are straight are haven't worn so that they are concave, this can cause the belt to flip if badley worn.