High Pitched whine at cold start up. lasts about 30-45 seconds. Not affected by engine speed. After engine warmed up does not re-occur unless engine cools off say half hour or so. Seems to be located on front driver side. Did find info about replacement of the air emissions pump on a chev that seems to most look like it, but have not confirmed that it is characterized by a high pitched whine at startup as indicated above.
how to test emissions air pump and replace on 2001 Cadillac DeVille
Most likely drive belt//tensioner or driven componet, have your mechanic remove the belt to see if that makes it stop, may need to let him/her keep it a while.
agree with wetry