The cost of replacing a Serpentine belt is typically between $100 and $200. The part cost can range from $20 to $50, and the labor costs are between $75 to $120. The actual cost of replacing the part will depend on the time it will take for the. 10. Apr 6, 2013. #9. The previous owner of my 1946 South Bend Model C (9") had installed a serpentine belt, rib side in, stitched with picture hanging wire. When I acquired it, last fall, I noted that the wire fell apart from fatigue. Still, when I first installed it, that's what I used, 'cause it was there.