18SP745 – EPA07/10 Three-Filter Fuel
System DD15/16 Severe Duty High Pressure Fuel Rail
Feed Lines Service Kit (P/N: 23539998)

PERSONAL INJURY
All parts provided within this kit MUST be installed in the proper locations, and
MUST be fastened to the specified torque. Failure to properly torque
hardware/components will result in failure of a high pressure fuel feed line, resulting
in possible fire and/or personal injury.

PERSONAL INJURY
All parts provided with this kit, and those they are replacing on the engine, function
as a complete system and are single-use items. The old parts cannot be reused.
Reusing parts or failing to use all new parts contained in the kit may result in the
failure of high pressure fuel lines, possibly resulting in a fire.

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NOTICE: Failure to follow these instructions will result in catastrophic damage to
the engine and will not be covered under warranty.
KIT DESCRIPTION
This service kit includes all the parts needed to replace high pressure fuel rail feed lines,
mounting bracket, P-clips, bolt-on Vibration Dampers and mounting hardware. Use this kit
when any of these parts are loosened, removed or missing from the engine.
KIT CONTENTS
Service kit P/N: 23539998 contains all the parts needed to replace severe duty high
pressure fuel rail feed lines on three-filter EPA07/10 DD15/16 engines.
Part No.
A4720781010
A4720703540
N000000007957
N910105008011
A4720701040
A0049902003
A4730700340
18SP745

Qty.
2
2
4
2
1
2
4
1

Description
High pressure fuel feed line
Solid P-Clip
Bolt M6x12mm
Bolt M8x20mm
Mounting bracket
E Torx Head P-clip Bolt M6X25mm
Bolt-on Vibration Dampers
Installation Instructions

18SP745. Page 2 of 12

Removal of Severe Duty High Pressure Fuel Rail Feed
Lines - Three-Filter System
Remove as follows:
NOTICE: The high pressure fuel rail feed lines, vibration dampers, P-clips, mounting
bracket and hardware are one-time use components and MUST be replaced any time they
are removed or loosened.

PERSONAL INJURY
To prevent the escape of high pressure fuel that can penetrate skin, ensure the engine
has been shut down for a minimum of 10 minutes before servicing any component
within the high pressure circuit. Residual high fuel pressure may be present within the
circuit.
1. Shut off the engine, apply parking brake, chock wheels, and perform any other
applicable safety steps.

ELECTRICAL SHOCK
To avoid injury from electrical shock, use care when disconnecting battery cables.
The magnetic switch studs are at battery voltage.
2. Disconnect the batteries.
3. Open the hood.
4. If necessary, remove the bumper. Refer to Original Equipment Manufacturer
(OEM) procedures.
5. If needed for access, remove the air cleaner. Refer to (OEM) procedures.
NOTE: Do not discard the return lines P-clip and bolt. They will be reused on the
installation of the high pressure fuel rail feed lines.

6. Remove the return lines P-clip bolt from the mounting bracket and save for re-use.
7. Remove and discard the two P-clip bolts from the mounting bracket.

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7. Remove and discard the mounting bracket bolts (2) from the intake manifold and
discard the mounting bracket (1).

1. Mounting bracket

4. High pressure fuel rail feed lines

2. Mounting bracket bolts

5. P-clips and E Torx bolts

3. Reused Return lines P-clip
NOTE: Hold the high pressure pump fitting with a 24 mm wrench when removing
high pressure fuel rail feed lines, If these fittings are loosened during high pressure
fuel rail feed line removal, re-torque the fittings to 75 N·m (55 lb·ft).
8. Remove and discard the high pressure fuel rail feed lines (4), P-clips (5), and
vibration dampers as an assembly from the fuel rail and high pressure fuel pump.
See graphic above.
9. Remove and discard the mounting bracket bolts (2) from the intake manifold and
discard the mounting bracket (1). See graphic above.

18SP745. Page 4 of 12

Installation of Severe Duty High Pressure Fuel Rail Feed
Lines - Three-Filter System
Install as follows:
NOTICE: The high pressure fuel rail feed lines, vibration dampers, P-clips,
mounting bracket and hardware are one-time use components and MUST be replaced
any time they are removed or loosened.
NOTE: DO NOT install bolts and fittings using power tools. All bolts and fittings
MUST be installed using hand tools.

PERSONAL INJURY
All hardware/components MUST be installed in the proper locations, and MUST be
fastened to the specified torque. Failure to properly torque hardware/components will
result in failure of a high pressure fuel feed line, resulting in possible fire and/or
personal injury.
1. Clean the sealing area inside the high pressure fuel pump outlet fittings using a
clean lint-free cloth.

2. Clean the sealing area inside the high pressure fuel rail using a clean lint-free cloth.
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NOTE: A new P-clip MUST be installed onto the high pressure fuel rail feed lines
with the lower P-clip plate (1) inserted into the P-clip window (2); see graphic below.

18SP745. Page 6 of 12

3. Before installing the lines, loosely install both of the new P-clips and four bolt-on
vibration dampers onto the high pressure fuel rail feed lines as shown in the graphic
below. Start the threads of the bolt-on vibration damper bolts but do not tighten.

4. Position the rear high pressure fuel rail feed line into the fuel rail and the high
pressure fuel pump. Do not start the threads of the fuel line nuts at this point.
5. Position the front high pressure fuel rail feed line into the fuel rail and the high
pressure fuel pump. Do not start the threads of the fuel line nuts at this point.

18SP745. Page 7 of 12

6. Install a new mounting bracket (1) and two new mounting bracket bolts (2) to the
fuel rail clamp. Hand-tighten the mounting bracket bolts all the way until the
bracket and bolts are flush. Do not torque at this time.

8. Ensure the rear high pressure fuel rail feed line is in place so that the P-clip
mounting hole lines up with the bracket nut. Do not apply excessive to any
components in the high pressure fuel rail feed lines kit during their loose assembly.
9. Install a new E Torx rear P-clip bolt hand tight. Do not torque at this time.
10. Hand-tighten the rear high pressure fuel rail feed line starting with the rail side nut,
and then the nut at the high pressure fuel pump.
NOTICE: After torqueing each fuel line nut, P-clip bolt, mounting bracket bolt,
vibration damper bolt and return line triple-clip bolt, mark the fittings and fasteners
with a paint pen. Draw a paint pen line on the fitting, fastener and adjacent metal as
shown in the photograph below. The photograph shows a two-filter system, the threefilter system is similar.

18SP745. Page 8 of 12

PERSONAL INJURY
All parts provided within this kit MUST be installed in the proper locations, and
MUST be fastened to the specified torque. Failure to properly torque
hardware/components will result in failure of a high pressure fuel feed line, resulting
in possible fire and/or personal injury.
11. Using fuel line socket W314589010300 or a commercially available 19 mm fuel
line socket, torque the rear high pressure fuel rail feed line nuts to 40 N·m (30 lb·ft)
starting with the rail side nut, and then the nut at the high pressure fuel pump. Using
a paint pen, draw a paint line on the torqued fuel line nut and adjacent metal, as
shown in the photograph above.
12. Ensure the front high pressure fuel rail feed line is in place so that the P-clip
mounting hole lines up with the bracket nut. Do not apply excessive force to any
components in the high pressure fuel rail feed lines kit during their loose assembly.
13. Install a new E Torx front P-clip bolt hand tight. Do not torque at this time.
14. Hand-tighten the front high pressure fuel rail feed line starting with the rail side nut,
and then the nut at the high pressure fuel pump.
15. Using fuel line socket W314589010300 or a commercially available 19 mm fuel
line socket, torque the front high pressure fuel rail feed line nuts to 40 N·m (30
lb·ft) starting with the rail side nut, and then the nut at the high pressure fuel pump.
Using a paint pen, draw a paint line on the torqued fuel line nut and adjacent metal,
as shown in the photograph above.

18SP745. Page 9 of 12

NOTE: New P-clips (1) MUST be installed perpendicular to the bracket (2) and
parallel with each other. Hold P-clips in place during tightening to avoid rotating the
P-Clips.

16. Torque the two new high pressure fuel rail feed line E Torx P-clip bolts to 14 N·m
(124 lb·in.). Using a paint pen, draw a paint line on the torqued bolt head and
adjacent metal, as shown in the notice after step 10.
17. Torque the two new mounting bracket bolts to 30 N·m (22 lb·ft). Using a paint pen,
draw a paint line on the torqued bolt head and the adjacent metal, as shown in the
notice after step 10.
18. Install the bolt for the amplification, needle, and pressure limiting valve return line
triple-clip. Torque to 14 N·m (124 lb·in.). Using a paint pen, draw a paint line on
the torqued bolt head and adjacent metal, as shown in the notice after step 10.
NOTE: Install the bolt-on vibration dampers with adequate clearance to surrounding
objects to ensure contact cannot be made with any components other than the high
pressure fuel rail feed lines.
19. Ensure the four bolt-on vibration dampers (1) are positioned properly on the straight
sections of the high pressure fuel rail feed line, parallel to the engine as shown in
the graphic below.

18SP745. Page 10 of 12

20. Once correctly positioned, torque the four bolts of the bolt-on vibration dampers to
14 N·m (124 lb·in.) starting with the front top vibration damper and the rear lower
vibration damper. Once all four are torqued, use a paint pen to draw a line on the
bolt head and adjacent metal.
21. Inspect all components of the high pressure fuel rail feed line kit to make sure all
fittings and fasteners have been properly installed, torqued and marked with a paint
pen. Have the lead hand or supervisor review the installation and sign off on the
repair order to ensure that all components were properly torqued and painted.
22. If removed for clearance, install the air cleaner. Refer to Original Equipment
Manufacturer (OEM) procedures.

ELECTRICAL SHOCK
To avoid injury from electrical shock, use care when disconnecting battery cables.
The magnetic switch studs are at battery voltage.
21. Connect the batteries.

18SP745. Page 11 of 12

22. Prime the fuel system. Refer to section "Priming the Fuel System - Three-Filter
System" .
23. Perform the Rail Pressure Bleed-Off test using DiagnosticLink® to verify that there
are no leaks.
24. If leaks are found, locate the leak’s source and repair, as necessary.
25. If necessary, install the bumper. Refer to Original Equipment Manufacturer (OEM)
procedures.
26. Close the hood.

13400 Outer Drive, West, Detroit Michigan 48239-4001
Telephone: 313-592-5000
WWW.DEMANDDETROIT.COM

Specifications are subject to change without notice. Detroit Diesel Corporation is registered to ISO 9001:2008.
Copyright © Detroit Diesel Corporation. All rights reserved. Detroit™ is a brand of Detroit Diesel Corporation,
a Daimler company.
18SP745. 2009 As technical advances continue, specifications will change. Printed in U.S.A.

18SP745. Page 12 of 12