When I did my 3L swap, the timing cover with both the idler and tensioner pulley were left out in the rain for a while. When I got the car running both pulleys were extremely loud.
Replacing both pulleys, it was perfect.
Tony
1998 SVT Contour (B/MB) #542 3L
1998 SVT Contour (SF/MB) #1266 parts car
2000 SVT Contour (SF/MB) #1533 3L swap to begin!