Loud tapping noise from car engine

The engine of a car (Toyota carina 1999 model) an 1800cc 7A4E engine made loud tapping noises. on performing a visual check I noticed that the pulley belts were turning by themselves (like a millimeter a second when the sound was being made. on trying to start the engine the battery was low and what seemed apparent to me was that the engine had been trying to turn itself, even though it was off!. on jump starting the engine turned on smoothly and has done approx. 20km after the incident. what would be the cause of the noise, and what are its probable consequences.
Asked Feb 08, 2010
your car may have jumped time. get a mec. to check it just to be safe.
Answered Feb 16, 2010

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