Why does my Audi 80's engine make a loud tapping noise at high speeds?

I recently bought a used Audi 80 and noticed that it makes a loud tapping noise when I accelerate at high speeds. The noise goes away when I let off the gas. What could be causing this and how can I fix it?

It sounds like the valve lifters may be worn or damaged. This can happen over time with wear and tear on the engine. I recommend taking it to a mechanic to have them checked and replaced if necessary.

Another possible cause could be a faulty oil pump or low oil pressure. This can cause the engine to make noises at high speeds. I suggest getting an oil pressure test done to see if the levels are within the recommended range. If not, you may need to replace the oil pump.

Before going to a mechanic, you can also try using a different type of oil with a higher viscosity to see if that reduces the noise. However, if the issue persists, it's best to have it checked out by a professional.