99 mazda protege

My 99 protege started squealing intermitently several months ago. I changed the belts, and the squeal disappeared for a few days. But, it started again! Seems to be worst when accelerating after a stop. New belts actually broke so took it to a mechanic who replaced water pump and timing belt and checked alternator. Didn’t squeal for a few hours following service work. But, then it started again. I’m at a loss.

Did he check the serpentine belt tensioner?

“New belts actually broke”.

Perhaps there is a pulley out of line.

Timing belts are toothed, and do not squeal, no matter what. The squeal is coming from one of the accessory drive belts (the ones you can see). If one of the new belts broke, it was probably because what it was driving is seized, and needs to be replaced. Which belt broke? Alternator? Air Conditioner Compressor? Power Steering?

Check to see (hear) if it squeals with the A/C on. If it does, the A/C compressor is likely the component which is putting excessive load on the drive belt, causing it to squeal. It could be one of the other belt driven components.