Suggestions on LS3 Belt Squeal

[BrianMoseley]

Looking for suggestions to resolve belt squeal issue. Last gremlin in my 68 Camaro custom build.

- LS3 with CTS-V serpentine setup
- Alternator still in low driver side position, but reversed due to interference with steering shaft
- Belt squeals at all engine speeds, sometimes a little less at idle when everything is up to temp
- No difference using factory tensioner or ICT manual tensioner with new pulley
- Noise goes away for a minute with talc powder on the belt, so not a bad bearing
- Have cleaned all pulleys and tried recommended belts
- My alternator mount consists of a spacer and weldment that attaches to block
- Alternator alignment looked perfect with good straight edge, I have not tried a laser alignment tool
- Leaning towards alternator alignment being cause but I don't know that for sure

See a lot of people discussing serpentine belt squeal with no consistent solutions.

Does anyone make a proven backwards alternator mount for this position? Any other suggestions?

For anyone who can contribute thanks in advance!
Brian

[Sinnister69]

Wow i have never seen an alternator mounted like that.
If i were you i would get the laser alignment tool its inexpensive and if you buy from summit or jegs its easily returnable

[dontlifttoshift]

Does the alternator move when you release the belt tension? I can't see from the pics but the mounts don't look rigid enough.

[BrianMoseley]

Not that I have noticed but it's a good thought to check more closely. I will pull cold air pipe off and have an extra person watch it. Laser tool would help with that too. I'll order one. I'm out of town so won't be for a few days.

[Hotwire]

Can you douse everything with powder, run the engine for a sec, then pull the belt to check witness marks? Might help to see where the belt is contacting everything and possibly where the squeal is generating?

[BrianMoseley]

Update:
I got a Gates 91075 laser alignment tool. It's better than nothing but if you're considering buying one, I would try a different brand/model.
I found it difficult to calibrate. The laser base didn't even fit inside the pocket on the plastic alignment tool. Ended up calibrating with laser attached to a spare tensioner pulley and long straight edge.
And the laser base does not seat very well on the pulleys so you can still wiggle it around a little.

When I put talc powder on the belt and start it up, the powder is completely gone after a short time with no evidence left.

I can tension and release the belt with no visible movement on the alternator itself. Including with laser alignment tool attached to look for motion in the laser beam.


I noticed that the 2nd and 5th grooves on the alt pulley had wear marks. So the belt seemed to have been contacting on that pulley fairly evenly.
I did make a very small change to alternator angle. This centered up the alignment in below picture.



Alternator position forward/back looked good.


When I fired the car back up the belt was almost totally quiet... for a short time. But after a little driving it went back to almost like it was.

I also noticed that the pulleys are super smooth. Wondering if roughing them up slightly could help. I have already cleaned with solvent and wire brush.

Thinking about trying what I said I'd never do and getting some belt squeal spray.

[Vimes]

I wouldn't rule out the other pulleys as causing the problem, even though the alternator is the change you made so I'd use the laser on the rest of the pulleys to make sure they're straight on. Also, is the belt the correct length or might it benefit from being a quarter or a half inch shorter? If the tensioner is on the loose side of the wear mark, a slightly smaller belt might correct the squeal.

On the alternator, while an alternator can spin in either direction and make electricity, the internal cooling fans are usually directional. And, if the alternator was on the car before, it may have worn in spinning in one direction and now you're spinning it in the other direction. No idea if any of that might cause a squeal but it would be worth checking into.