Step 3 · Mount the Air Gap Body
Unpack your new dishwasher air gap kit. From above the counter, feed the threaded body of the air gap through the hole you just drilled. Some kits rely on a rubber gasket for sealing, while others recommend a small bead of plumber's putty under the flange. If using putty, roll a small amount into a snake and wrap it around the underside of the air gap's top flange before inserting it. From underneath the sink, slide the rubber washer and then the metal friction washer onto the threaded body. Thread on the large mounting nut and hand-tighten it. From the top, align the air gap so the decorative cover will face the desired direction, then use channel-lock pliers or an adjustable wrench to give the mounting nut a final quarter-turn to secure it firmly. Do not over-tighten. Wipe away any excess putty.