Changing a Fuel Filter on a GM 6.5 Diesel

Glow Plug Article
Fuel Bowl Drain Light

This is the new filter design. It's a WIX 33976 or Hastings FF943

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1998 H1 - The Fuel filter is on the right and the fuel pump is on the left.

 

Showing the Long and Short Alignment Slots.

 

Notice the slots in the fuel Bowl and the O-ring seal

• Turn the engine off
• On 1999's and newer: Loosen the two screws that hold the CTIS compressor in place.
• On 1999's and newer: Move the CTIS compressor forward towards the radiators to give yourself room. The silver cylinder with a black round cap in the center is the fuel filter assembly.
• Clean up the area surrounding the filter and retaining ring.
• Unscrew the black cap that encircles the entire assembly. If it's really tough to turn just use a strap wrench or an oil filter wrench. If it still won't loosen use a screwdriver and a hammer to tap the retaining ring in a counter clockwise direction to loosen it a bit.
• Clean off all the dirt on the retaining ring and filter housing threads.
• Coat the retaining ring threads with grease.
• Remove the old fuel filter by grabbing the white tabs and pulling directly up and out. Make sure you remove the old O-ring. If you put the new filter in on top of the old O-ring it will leak.
• Look at the new fuel filter. There's one wide alignment slot on the filter that fits over the wide 'tooth' on the canister filter holder. These must be lined up.
• Slowly put the fuel filter in by pushing it straight down. It doesn't turn or twist, just goes straight in. Remember to line the tooth and the slot up. If you pull it out and put it in a couple of times it's possible to screwup the black sealing O ring. You will usually have to get another new filter.
• Screw on the retaining ring and tighten it with your hand, not a wrench. The ring seems to cross thread easily.
• Loosen the very top black air purge cap 1/4 turn and turn on the key for 10 seconds or until you see fuel coming out the hole in the cap. This will purge the air and allow the fuel bowl to fill with fuel.
• Start the engine and check for leaks. Realize you can have leaks from the front fuel line going into the injector pump and the lines going into the bottom of the  fuel filter housing. 

Seal on the fuel filter. - Grease the threads on the retaining ring.