I don't think i have ever had this problem.3000rpm and above,belt that runs water pump, p/s pump squeals.I have sanded pulleys changed w/p,tried different fan combos nothing helps.Its a new set up,squealed from day one.383 .040 over, pulleys off a 440 m/h.pulleys align with straight edge and don't wobble.please help,pulling what hair i have left out.thanks ,BILL

Inquiring minds want to know....
I currently have the same issue kicking my azz!

Belt sitting down in the pulley grooves correctly? There is a difference in belt angles and width. You might want to replace the belt anyway because once it starts squealing it gets heated up and hard so it will continue to squeal even if you have fixed the original issue.

Yes,i have checked pulley grooves ,no wear in bottom of grooves and have changed belt 3 times now (gates).

never had it to fix, but have you considered changing the belt width?
I haven't looked in a while, but one of the numbers decides how wide it is.
go wider to see if it will grip better? or smaller to sit in the grove a bit more?

The belt should fit in the groove tightly. If you show no wear in the bottom of the pulley then maybe the belt is too wide. It should go all the way into the pulley groove and show contact from the top to the bottom without bottoming out. In other words the belt angle and width should be the same as the pulley. General example, a 1/2" belt will work on a 7/16" pulley but still won't fit right.

add one of our serpentine belt kits with a spring loaded tensioner and no more belt squeal

I always thought that if a pulley or belt was worn enough that the belt touched the bottom of the groove that that WAS the problem (but I may be all wrong there). if your pulleys are aligned) & belt tight which I'm sure it is by now) then it about has to be wrong/worn belt (likely) or worn pulley (way less likely). Holler how it goes.

Is the whole setup original style? If anything has changed to reduce pulley wrap that has an impact. The fan seems to be toughest to drive.

If the fan clutch is extra tight or locked up that could be the problem. If your are running a viscous fan clutch (hope so) it should slip to a certain extent at higher RPM to help prevent fan overspeed and belt overload.

Also, FWIW, I believe I have run 3/8" belts in pulley's designed for 5/16" belt w/o problem.

Cogged belt?

Ed

When ever I've experienced this before, I have corrected the problem wit all new (or different) pulleys and new belts. Once off the motor, I can usually see the wear on the pulleys. The sides of the belt groove are usually straight for about 1/4 of the depth before they tapper towards the center. This causes the belts bottom out in the groves and slip. If you look at the belts you remove, are the outside top edges worn away just a little, or maybe curled up a bit?
The alt and the bottom pulleys are often the ones most often damaged. We must change the water pump pulley more often, or maybe it is better material. Gene

Every Gates belt Ive used squeals. Add a Dayco Top Cog and it goes away. Everytime.

Old change the belts to dayco top cog as in earlier post. My hemi would throw and break belts at rpms until I switched. No problems in 8 years. I was able to get a deal on a bunch of different sized unused belts from a nascar team to see what length fit best. I ended up with the 15470 for alternator and 15440 for power steering.

The first 2 numbers mean it’s 15mm or 7/16 wide the last 3 are length. The last number can be a 5 for half inch. So if yours fix good just measure them in inches and add that number to the 15.

I will bet your problem will be over with the new belts.

The first 2 numbers are the width- 15 mm, the last 3 numbers are the length-47 and 44 inches long. All of our older Mopars were designed to use the 13 mm wide belts, pretty much unavailable today. 95 % of the Mopars use the 15 series belt which ride up out of the pulley a little amount.

Thanks lemondana I stand corrected. I was going off of memory which wasn't working correctly. But I do know theses belts work.