Other Category problem
1991 Other Audi Models 4 cyl Front Wheel Drive Manual 151000 miles
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while driving the car it made a thud sound and felt like the transmission down shifted after pulling over and shuting car off and restarting the car started making a screeching sound and the screeching gets loader as I accelerate, any ideas on what could be wrong?

Hi there,

This is a bit hard to diagnose from what you have reported. If the noise is there in park or neutral and constant with engine speed (or there abouts) I would be looking at an engine driven accessory or engine mechanical problem, if there when driving only it will be a transmission or drive line problem.
Start looking there.

Mark (mhpautos)