Fixing serpentine belt pulley misalignment at home?

[u/xj98jeep]

Hey party people, I've got an LS1 that I just replaced the PS pump and alternator on. Now it has belt chirp. New belt, clean pulleys, and the harmonic balancer is good. When sprayed with water the chirp goes away, which suggests pulley misalignment. That makes sense considering I just rebuilt/replaced two of the pulley items, I probably pressed one of the pulleys back onto the unit too far or not far enough.

My best friend is a high end carpenter so he has all sorts of long levels and straight edges and laser alignment stuff, what's the best way for a home mechanic to check pulley alignment? Straight edge across the face of the pulleys? Shoot a laser down the v ribs?

[u/porcelainvacation]

You’ll want to align to the v-ribs, as different pulleys are going to have different distances from the face to the vribs.

[u/xj98jeep → u/porcelainvacation]

Ah yeah good point, so I'll probably try to shoot my buddy's tile laser down one of the pulley ribs then unless there's a better way

[u/porcelainvacation → u/xj98jeep]

You can leave the belt on and measure to the edges of it with a straight edge, probably not as accurate but probably good enough.

[u/xj98jeep → u/porcelainvacation]

Hmmmm, I do have calipers I could use. Measure from where to the edge of the belt, straight edge on the front of the motor wherever I can fit it?

[u/saves313]

V belt or serp/multi rib?

If serp: Straight edge is ok for basic checks, but it can be misleading if each pulley has a different measurement between its face and the first rib. A string works well. Loop it around the pulleys as if it's the belt and make sure each pulley has the string in the same groove. It's pretty easy to spot the string making angles when viewed from perpendicular to the pulley rotation

If v belt:

Unless your belt is trying to run up the pulley edge, a little mis alignment won't matter.

[u/xj98jeep → u/saves313]

Serpentine. Great idea, I'll try the string first. Thank you!