Why is my car making a rattling sound around the crankshaft area? on 1998 Nissan Sentra

When I rear up the engine the sound is not present but when it go to a normal idle the sound comes back.

by in Miami Beach, FL on April 28, 2013
2 answers
ANSWER by on April 29, 2013
1- Have 'entire' drive belt systems checked, can remove belts, one at a time, to see if noise stops. 2- Possible cat. converter rattle.
ANSWER by on April 29, 2013
agre with wetry or poss frt crank pulley falling apart