Accessory belt squeal

[bugleg]

I'm having a hard time tracking down a squeal under load from my accessory belt.

It started after I got the power steering pump replaced by a shop while traveling. I put on a slightly shorter belt and it went away for about 6 months, but then came back when on a long highway trip.

Since then I've replaced the tensioner and idler pulley, the power steering pump (the one the shop installed was about 1/8" out of alignment with the idler and AC pulleys) and most recently the alternator when I realized the clutch had seized.

I just swapped out a fresh belt since there was some wear on the backside and edges of the previous one, but same squeal is happening when I give it more than 20% throttle.

What could be going on here?

[Duece McCracken]

I'm having a hard time tracking down a squeal under load from my accessory belt.

It started after I got the power steering pump replaced by a shop while traveling. I put on a slightly shorter belt and it went away for about 6 months, but then came back when on a long highway trip.

Since then I've replaced the tensioner and idler pulley, the power steering pump (the one the shop installed was about 1/8" out of alignment with the idler and AC pulleys) and most recently the alternator when I realized the clutch had seized.

I just swapped out a fresh belt since there was some wear on the backside and edges of the previous one, but same squeal is happening when I give it more than 20% throttle.

What could be going on here?

Any signs of contaminates? Oil, coolant, PS fluid. Did you brake clean the pullies just to be sure?

Seems you have addressed most of the mechanical alignment and tension components. Not too much else to the acc drive belt system.

[CycloSteve]

Back in the day when working at Chevron we used a Belt Dressing Stick. Not sure if that would be appropriate with the VAG style ribbed belts, but it worked great on v-belts. The AC compressor on my B5 squeals if AC is engaged on startup...after warmed up it is fine.

[a4audi4fun]

Small amount of soapy water may have the same effect as the belt dressing stick - that's what my mechanic Dad would use on vehicles back in the day

[Cyrik]

I just swapped out a fresh belt since there was some wear on the backside and edges of the previous one, but same squeal is happening when I give it more than 20% throttle.

What could be going on here?

Slightly late to the party but your serpentine belt isn't a DAYCO belt is it? Those things squeak. Every. Single. Time.

Small amount of soapy water may have the same effect as the belt dressing stick - that's what my mechanic Dad would use on vehicles back in the day

Can confirm this is a little mechanic trick but I have also seen a tiny bit of die-electric grease on the ribbed-side of the belt can also get them to quiet down a bit.