"Speak to town mechanic" is an objective in the Story Mission Plan B in Borderlands 2
Walkthrough
Head for the Mechanic's shop which is the first big building you see. You can go in through either of the shutter doors in the front or go around to the side door on the right. Go inside and to the floor to meet the Mechanic: Scooter. Talk with him to get things moving. He will give you 4 pieces of Eridium as well.
