Common reasons for this to happen:
Drive or auxiliary belts are worn
The most frequent cause of a car making screeching sounds is that the drive belts or auxiliary belts are old and need to be replaced. When your belts start to wear out and fray, the oils within them will come out and encourage all forms of screeching and slapping sounds.
Tensioners and pulleys are worn
The pulleys and belt tensioners that keep your belt in place can also wear out over the course of time. The tensioner helps keep the belt in place and under the right alignment, while the rubber inside your pulley helps absorb the vibrations that are generated from your engine. If this rubber part wears out, your belt may also begin to have wear issues.
Wrong torque, alignment or belt size
If the torque and alignment on the belt tensioner and pulley are incorrect, your belt may not have the proper pressure on it. Also, there are times when the wrong size belt has been installed. Different engines require different belts. If a belt is too big, it will start making sounds as well.
What to expect:
A top-rated mobile mechanic will come to your home or office to determine the source and cause of the screeching noise, and will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.
How it’s done:
The mechanic will inspect the belts to see whether they are cracked, worn, or frayed. From there, the tensioners and pulleys may be looked at as well to make sure they are up to spec. Minimal wear and a good fit make all the difference with a screeching belt.
How important is this service?
Belt, pulleys, and tensioners make the difference between a quiet, perfectly running car, and a noisy one that may later result in a long list of repairs. Belts can snap due to age or improper installation, and big things like your engine can break, so it’s advisable to get this issue diagnosed as soon as possible.