The units are designed in such a way as to provide quick and easy installation that at the same time results in a “non-removable” unit. This is made possible by a combination of locating systems including special snap-off screws and adaptors with locking pins that secure the unit onto the existing filler neck of the vehicle. The purpose of this design is to prevent drilling and riveting wherever possible.

1a-bayonet-type-1-01                1a-bayonet-type-2-01

Step 1. Remove the existing cap and detach chain at filler neck.

Step 2. Remove the plastic sleeve.

1abayonet-type-3-01                1a-bayonet-type-4-01

Step 3. Fit the Diesel Guard unit into the filler neck and turn and lock in place.

Step 4. Finger tighten the bolts.

1a-bayonet-type-5-01                1a-bayonet-type-6-01

Step 5. Tighten the bolts evenly with a socket spanner (8mm) one turn at a time until the heads break off.

Step 6. Re-attach the chain and cap.

2b-bayonet-double-1-01                2b-bayonet-double-2-01

Step 1. Remove the cap.

Step 2. Insert the Diesel Guard’s bottom lugs into the filler.


2b-bayonet-double-3-01               2b-bayonet-double-4-01

Step 3. Turn the Diesel Guard unit a quarter turn and let the top lugs into the filler.

Step 4. Turn the Diesel Guard unit another quarter turn until you can see the bottom lugs through the round hole in the top plate.

2b-bayonet-double-5-01               2b-bayonet-double-6-01

Step 5. Insert the snap off bolts carefully through the round hole and line up with the thread in the bottom lugs and bit by bit tighten until they snap off.

Step 6. Attach the cable supplied around the neck and crimp in place with the ferrule supplied. Thread on the cap supplied.


3c-metal-tank-1-01                3c-metal-tank-2-01

Step 1. Place the Diesel guard mechanism into the filler neck.

Step 2. Screw the adapter supplied into the filler neck. Make sure that the DG is secure and cannot move – use a filter strap if necessary.

3c-metal-tank-3-01                3c-metal-tank-4-01

Step 3. Insert the three dowel pins supplied into the holes in the adapter.

Step 4. Take a flat punch and knock the 3 dowel pins in until they are flush

4d-ex-plastic-tank-1-01                4d-ex-plastic-tank-2-01

Step 1. Remove the cap and filter.

Step 2. Place the Diesel Guard into the filler neck.

4d-ex-plastic-tank-3-01                4d-ex-plastic-tank-4-01

Step 3. Screw the adapter onto the filler neck. Make sure that the Diesel Guard in the filler cannot move.

Step 4. Screw the snap-off bolt into the thread on the side of the adapter and turn until it breaks off.


Step 5. Replace the cap.

5e-int-metal-plastic-1-01                5e-int-metal-plastic-2-01

Step 1. Remove the cap

Step 2. Fit the Diesel Guard into the filler neck and screw in until tight. Do not over tighten.

5e-int-metal-plastic-3-01                5e-int-metal-plastic-4-01

Step 3. Use a flat punch and hammer to knock in the 3 pins or wedges supplied – a little at a time.

Step 4. Knock the pins or wedges in until they are flush.

Step 1: Unbolt the existing filler neck and remove from the tank.

Step2: Place the Diesel Guard into the hole in the tank, lining up the holes.

Step 3: Bolt the Diesel Guard onto the tank by alternating the normal bolts with the snap-off bolts.

Step 4: Fit the cap supplied.

7g-freightliner-1-01                7g-freightliner-2-01

Step 1. Remove the cap and factory fitted aluminum sleeve.

Step 2. Put a screwdriver into the ring and pull on the cap – levering the screwdriver to remove the cap and chain.

7g-freightliner-3-01                7g-freightliner-4-01

Step 3. Pull the cap until the ring on the end of the chain appears in the neck.

Step 4. Manipulate the aluminum sleeve with a screwdriver and pliers if necessary.

7g-freightliner-5-01                7g-freightliner-6-01

Step 5. Remove the aluminum sleeve.

Step 6. Open the security legs of the Diesel Guard with a screwdriver.

7g-freightliner-7-01                7g-freightliner-8-01

Step 7. Pull the slide out and push quickly into the filler neck.

Step 8. The unit should lock into place and look like this.

8h-taperloch-1-01                8h-taperlock-2-01

Step 1. Take the Diesel Guard apart.                                  Step 2. Take the diesel cap off.

8h-taperlock-3-01                8h-taperlock-4-01

Step 3. Put the locking ring (1) over the filler neck. Make sure the wide end of the OD is facing up.

Step 4. Place the tapered ring (2) over the filler neck.

8h-taperlock-5-01               8h-taperlock-6-01

Step 5. Push it down so that approximately 5mm of the filler neck stands out.

Step 6. Insert the sieve section into the filler neck. Make sure that the slotted section faces down and the blank section is up.

8h-taperlock-7-01                8h-taperlock-8-01

Step 7. Place the body (3) into the sieve.

Step 8. Put the snap off bolt through the body and attach it to the locking ring.

8h-taperlock-9-01                8h-taperlock-10-01

Step 9. Follow step 8 for all 4 bolts.

Step 10. Finger tighten the bolts little by little on each one.

8h-taperlock-11-01             8h-taperlock-12-01

Step 11. Tighten with a 12mm spanner little by little one each until the heads snap off.

Step 12. Loop the wire cable around the filler neck and then crimp the ferrul so that the loop cannot come over the Diesel Guard.

9I step 1-01                9I step2-01

Step 1. Remove the cap.

Step 2. Insert the Diesel Guard into the filler neck.

9I step3-01               9I step4-01

Step 3. Place the adaptor over the filler neck.

Step 4. Drill the adaptor into the tank.

9I step5-01                9I step 6-01

Step 5. Pop rivet the adaptor onto the tank one at a time.

Step 6. Screw the cap onto the adaptor.

10J step 1-01          10J step 2-01

Step 1. Remove the cap.

Step 2. Remove the two circlips & mesh basket if still there.

10J step 3-01          10J step 4-01

Step 3. Remove the circlip supplied off the diesel Guard unit.

Step 4. Close the circlip provided so that it will fit down the filler neck. Tie a piece of cotton around the circlip and attach to your finger in case you drop it.

10J step 5-01          10J step 6-01

Step 5. Push the circlip into either of the two grooves.

Step 6. Slide the wedge provided into the gap in the circlip. Tap the wedge until the top of the wedge is almost level with the top of the filler neck.


10J step 7-01          10J step 8-01

Step 7. Open the security legs with a screwdriver.

Step 8. Pull out the slide, lock into place. Line the wedge up with the recess in the top plate and push quickly into place. See fitted Diesel Guard unit below.

10J step 9-01

Step 9: Installed.

11K step 1-01          11K step 2-01

Step 1. Remove the cap.

Step 2. Place the two half circles under the lip of the filler neck.

11K Step 3-01          11K Step 4-01

Step 3. Place the Diesel Guard over the filler and the 2 half circles.

Step 4. Line the holes up and tighten the snap off bolts a bit at a time until they break off.


12L Step 1-01               12L Step 2-01

Step: Remove the cap.

Step 2:  Insert the Diesel Guard, making sure the lugs are hidden.

12L Step 3-01               12L Step 4-01

Step 3: Open lugs out and finger tighten all the sliding bolts.

Step 4: Screw in the bolt closest to the sliding bolt until just tightened.

12L Step 5-01               12L Step 6-01

Step 5: Finger tighten the remaining bolts.

Step 6: Snap off all bolt heads.

12L Step 7-01

Step 7: Replace the cap.

13M Step 1-01               13M Step 2-01

Step 1: Remove the cap.

Step 2:  Insert the Diesel Guard.

13M Step 3-01              13M Step 4-01

Step 3: Place the adaptor onto the filler neck.

Step 4:  Slide the first half of the split ring under the Diesel Guard, lining up the holes.

13M Step 5-01               13M Step 6-01

Step 5: Insert the first 3 snap-off screws and tighten.

Step 6: Repeat steps 3 and 4 for second half of split ring.

13M Step 7-01

Step 7: Screw the cap onto the adaptor and tighten the wire loop.

DG0119: Weld on taking all necessary precautions.

DG0506: Weld on taking all necessary precautions, or pop rivet on through the holes in the collar.

DG0118: Refer to fitting instructions 1A and 6F with some adaptation.

DG0511: Weld on taking all necessary precautions.

15O Step 1-01               15O Step 2-01

Step 1: Remove cap and two bolts on either side of the filler neck.

Step 2: Insert the Diesel Guard.

15O Step 3-01               15O Step 4-01

Step 3: Place the adaptor onto the filler neck.

Step 4: Slide the first half of the split ring under the Diesel Guard, lining up the holes.

15O Step 5-01

Step 5:  Screw the cap onto the adaptor and tighten the wire loop.