I ask the same question to GM and they told me that it is a cold motor piston slap and should go away once the motor is warmed up. The garage told me that it is normal and not to worry.
The loud tapping sound can be caused by a complete heating of the engine. Worn tappets can also cause the tapping sound.
There are several reasons that can cause your 1995 Buick Century to quit running. The most common reason is a lack of fuel. A bad fuel pump can cause the engine to quit running.
what will cause a transmission in a 1992 buick lasebre to shrudderas and stall engine
Stuck hydraulic lifter.
loose exhaust
where is the Kill start button on a buick century 2003?
after market oil filter have been known to cause engine noises in kia's
old fuel filter
A loose rocker arm for a valve mite be a easy fix with a valve adjustment
That might be the PCV pipe or some other vacuum leak. That will cause stalling.
Check the belts. The most common cause of squealing is a worn or loose belt on the front of the engine.
Valves tapping?