What is causing a squeaking noise in my 1990 Audi 80's engine?

I recently purchased a used 1990 Audi 80 and have been experiencing a loud, high-pitched squeaking noise coming from the engine. It only occurs when the engine is running and seems to increase in frequency as I accelerate. What could be causing this issue and how can I resolve it?

The most likely cause of this issue is a worn or damaged serpentine or fan belt. These belts are responsible for powering accessories such as the alternator, air conditioning, and water pump. If they become worn or misaligned, they can produce a squeaking noise. It is important to have these belts inspected and replaced if necessary to avoid potential damage to your car's engine.

Another possible cause of the squeaking noise could be a loose or damaged pulley. The pulley is responsible for guiding the belt and if it is not functioning properly, it can create a squeaking sound. You may need to have the pulley tightened or replaced to resolve the issue.

In some cases, the squeaking noise may be caused by low or dirty engine oil. It is important to regularly check and change your oil to ensure proper engine function and avoid potential issues such as unusual noises. Consider scheduling an oil change if it has been longer than 6 months since your last one.