How To Install or Replace a Conventional MIG Welding Liner

NOTE: For MIG guns equipped with 'Direct Plug-Ins', Bernard™, or Euro connector, the procedure is the same. On Miller® style guns, the liner is held captive by a guide cap which must be removed and replaced when changing the liner.


NOTE: Ensure the power supply is off and the gun is removed from the feeder before proceeding.

  • Remove the nozzle, contact tip and gas diffuser.
  • If the power pin uses a liner set screw, loosen the set screw using a 5/64 inch Allen wrench.
  • If the power pin is a thread-in liner type, using a 10-mm wrench, turn the thread-in liner collet counterclockwise until the liner is free from the power pin.
  • With the gun straightened, grip the conduit liner with pliers and remove.


  • Feed the replacement liner through the gun using short strokes to avoid kinking. Twist the liner clockwise if necessary.
  • If the power pin uses a liner set screw:
    • Seat the liner retainer with o-ring to shoulder inside the bore of the power pin.
    • Secure by tightening the liner set screw. Do no overtighten.
  • If the power pin is the thread-in type:
    • Using a 10-mm wrench, turn thread-in liner collet in a clockwise direction and tighten in the power pin.


  • Push the liner back into the gun and hold in place.
  • Using the Liner Gauge, trim the conduit liner with a 3/4" (20 mm) stick out.
  • NOTE: When using 154 or 454-1 retaining heads, trim the conduit liner with a 1/2" (13 mm) stick out.
  • Remove any burr that may obstruct wire feed, especially on flat wire type conduit liner.
  • Replace the nozzle, contact tip and gas diffuser onto the neck.