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How to Replace the Fuel Filter on a Duramax 6.6 Turbo Diesel

by Thomas West; Updated November 07, 2017

Items you will need

  • Fuel filter wrench

  • Drain pan

  • Water separator wrench

  • Replacement fuel filter kit

  • Flat-head screwdriver

The 6.6 liter Duramax diesel engine is manufactured by General Motors and has been used in the Chevrolet and GMC trucks since 2001. Still in production as of 2010, the Duramax is an eight-cylinder, turbocharged engine that is optional to those needing more power and torque than offered by the standard gasoline engine available for these truck models. The Duramax fuel filter is located in the engine compartment, and it ensures that clean fuel is supplied to the fuel injection system.

Open the hood and locate the fuel filter on the passenger's side of the engine bay, near the firewall. Allow the engine to cool down, if it has been running.

Depress the two release tabs on the wiring connector located on the water separator mounted on the bottom of the fuel filter. Pull the wire downward and out of the water separator.

Place the jaws of a filter wrench around the fuel filter. Turn the wrench in a counterclockwise direction to loosen the filter from the mounting. Remove the wrench and finish twisting off the filter by hand. Lower the filter straight down and let it rest on the frame rail.

Grasp the edges of the plastic passenger side wheel well liner from outside the vehicle, behind the front wheel, and pull it downward. Reach in the opening and remove the filter from the frame rail. Empty the fuel from the filter into a drain pan.

Remove the white, plastic water separator from the bottom of the fuel filter with a special wrench available from auto parts stores. Remove the old O-ring from the separator and push on a new one from your new fuel filter kit. Thread the separator onto the bottom of the new fuel filter and tighten it with the special tool.

Remove the old filter gasket and place a new one from your fuel filter kit into the same position. Place the filter in an upright position on the frame rail through the opening in the wheel well liner. Push the liner back into position until it snaps into place.

Reach down and pick up the filter from the engine compartment and raise it to the filter mounting surface. Thread the filter into place by hand, then tighten it with the filter wrench. Push the water separator connector back into the wiring harness connector until it locks into place.

Loosen the black bleeder screw on top of the fuel filter housing with a flat-head screwdriver three turns. Pump the round pump handle on top of the filter housing until fuel starts to seep from the bleeder screw. Tighten the screw. Start the engine and check for leaks. Tighten the filter further with the filter wrench, if necessary. Close the hood.

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