REPLACEMENT OF ORIGINAL
CANISTER-TYPE PRIMARY FUEL FILTER AND HEAD
WITH NEW SPIN-ON FUEL FILTER HEAD AND FILTER
ON AN M35A2 TRUCK

Why do it in the first place ?

The new filter head makes filter changes quick and easy.  Disassembly of the old canister units is no longer necessary.  You simply spin off the old filter and spin on on a new filter.  That's it.

Step by step instructions

It is best to work on the fuel system after the truck has been standing still for some time so that the fuel lines are not under pressure.

1.  Collect tools needed: 
  • 9/16" and 3/4" open ended wrenches,
  • one or two pairs of locking pliers,
  • a small container for reusable parts,
  • safety goggles,
  • a jar to catch fuel,
  • a larger container (pizza size recommended) to catch dripping fuel,
  • a pair of gloves.
2.  Put on safety goggles when you work under the truck so that dirt, oil, fuel, clumps of once caught underbrush, or even some of your tools will not fall off and into your eyes.
3.  Hold the jar under the primary fuel filter canister.  Open the valve (shown on the right in the picture) and allow the fuel to run out and into the jar. 

This step helps avoid spillage when you remove that filter canister later.

When the dripping stops, close the valve, close the jar and put it aside.  I do not suggest you put the dirty fuel from the dirty filter canister back into your tank.

4.  Disconnect both fuel lines from the inlet and the outlet of the old head by turning the nuts that are farthest from the filter head. 

The closer nuts are part of the filter and are not to be removed.  The elbow remains on the filter head.

In the picture, the fuel lines have been separated from the filter head and pulled out.

5.  Pull both fuel lines all the way out.

6.  Apply locking pliers to one of the nuts on the bolts that attach the head to the frame.

7.  Open engine hood. 

Secure hood.

 
8.  Looking down through the open engine hood, check to which nut you applied the locking pliers.

Loosen and remove the corresponding bolt.  Be sure to collect the bolt, nut and washers and store them in the small parts container.

9.  Apply locking pliers to the other nut on the frame.

10.  Loosen and remove the corresponding bolt from atop. 

Be sure to collect the bolt, nut and washers and store them in the small parts container.

11.  Carefully protect the now loose ground wire.

12.  Pull the old head and filter canister from the frame. 

If you emptied the filter earlier as suggested, you won't have to worry about spillage as you remove the filter and head now.

13.  Clean your work area if necessary.  Remove grease, paint chips, dirt from the frame.

Make sure no sharp objects remain on the ground where you work.

14.  From top of the engine, slip the end of the ground wire and washer over the bolt.

15.  Insert that bolt into the hole of the new filter head.

16.  Align the holes and push the bolt through the frame from above.

17.  From under the truck, screw on the nut and apply the locking pliers.

On my truck, one bolt also secured a clamp (shown on the far right in the picture) to the frame.

18.  From atop, tighten the bolt firmly.

19.  From under the truck, screw on the other nut and apply the locking pliers.

20.  From atop, tighten that other bolt firmly.

21.  Remove the pliers and check if the new head is properly secured.  If it is loose, tighten the bolts again.

22.  Check your parts container.  It should be empty now.

23.  Reconnect both fuel lines.  You may have to pull them a bit to align them properly with the filter inlet and outlet.

I had a gap of about a half an inch on one side.  (Look at the fuel line on the right side of the new head.)

24.  Tighten both fuel lines.

25.  Wipe off the bottom of the new head if necessary.  It must be clean.

26.  Open the filter pack.  It should contain
  • the head (shown in front of the filter unit),
  • one filter ready for spin-on installation and
  • one gasket.

27.  From below, slip the gasket over the threaded center of the head.  Push it all the way up.

28.  Wipe a little clean diesel over the gasket that is on the filter.

29.  Spin the new filter on.

30.  When you feel that the filter makes contact with the head, turn it another 1/2 to 3/4 revolution.

31.  Collect your tools from under the truck.

32.  Position the large container under the secondary and final fuel filters.

33.  Put on your gloves before you bleed your fuel system.

34.  Open the bleeder valve, or both valves if you have two.

35.  Turn the power switch (accessory switch) on.  The fuel pump will now pump fuel through the tubes into the new filter and beyond.  At first, diesel will come out of the valve, then diesel and air.  Wait until all the air has escaped. 

36.  When you see 100% fuel and no more air come through, turn the power switch (accessory switch) off.

37.  Close the valve.

38.  Check for leaks in the system.  Fix if necessary.

39.  Turn the power (accessory) switch back on and start the engine.

40.  While the engine is running, check for leaks again.  Fix is necessary.

41.  Next, you can also bleed at the injectors.  I skipped that step.

42.  Put a replacement filter into the truck.  You should always have a spare filter handy.

The filter I removed from the truck.

Three pictures of the new filter kit.

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