Removal and Replacement
Fuel System Assembly Overview
• Hoses are secured with spring-type clips.
• Pliers for spring clamps (VAS 6362) or Hose clamp pliers (VAS 6340) are recommended for installing spring clamps.
CAUTION!
• Follow the safety precautions when working on the diesel direct injection system. Refer to --> [ Safety Precautions ] Safety Precautions.
• Observe rules for cleanliness. Refer to --> [ Clean Working Conditions ] Clean Working Conditions.
Always follow these instructions before and during work.
Follow the points below to avoid running the high pressure fuel pump dry and to start the engine quickly after replacing the components:
• If fuel system components between the fuel tank and high pressure fuel pump are removed or replaced, perform a basic setting "Transfer Fuel Pump, Checking" to bleed the fuel system.
• If a fuel pump, fuel line or fuel filter was removed or replaced, perform the basic setting "Transfer Fuel Pump, checking" 1 time before starting the engine for the first time.
• If the high pressure fuel pump was removed or replaced, perform the basic setting "Transfer Fuel Pump, Checking" 3 times before starting the engine for the first time.
1 Protective Strip
• For rail element (high pressure reservoir) --> [ 7 Rail Element (High Pressure Reservoir) ] and high pressure lines --> [ 5 High Pressure Lines ]
2 Fuel Return Lines
• With pressure retaining valve --> [ 8 Pressure Retention Valve ] [1][2]Diagrams
• Do not disassemble fuel return lines. They can only be replaced completely with the pressure retaining valve.
• After replacing, run the engine at idle for approximately 2 minutes to bleed the fuel system, then check the fuel return lines for leaks.
• Refer to --> [ Pressure Retention Valve in Fuel Return Line, Checking ] Testing and Inspection.
3 8 Nm
4 Fuel Return Line
• Blue or with blue marking
• Ensure seated tightly
• From fuel filter --> [ 7 Fuel Return Line ] Fuel Filter Assembly Overview
5 High Pressure Lines
• Between rail element (high pressure reservoir) --> [ 7 Rail Element (High Pressure Reservoir) ] and fuel injector --> [ 20 Injection Unit (Piezo Injector) ]
• Do not interchange
• When installing, the fuel injectors --> [ 20 Injection Unit (Piezo Injector) ] and high pressure lines may only be installed on the same cylinder as before.
• Do not change the angles of the high pressure lines
• Install without tension
• Tightening specification: 25 Nm
6 Fuel Pressure Regulator Valve (N276)
• Removing and installing, refer to --> [ Fuel Pressure Regulator Valve ] Service and Repair.
• Tightening specification: 80Nm
7 Rail Element (High Pressure Reservoir)
8 Fuel Temperature Sensor (G81)
9 Fuel Supply Line
• Ensure seated tightly
• Between fuel temperature sensor (G81) --> [ 8 ] and high pressure fuel pump --> [ 10 Fuel High Pressure Pump ]
10 Fuel High Pressure Pump
• With fuel metering valve (N290) --> [ 1 ] [1][2]Diagrams
• Removing and installing, refer to --> [ High Pressure Fuel Pump ] High Pressure Fuel Pump.
• The fuel system must always be filled after replacing (never run dry). Refer to --> [ Fuel System, Filling ] Fuel System, Filling.
11 20 Nm
12 Bracket
• For fuel temperature sensor (G81) --> [ 8 ]
13 Fuel Supply Line
• White or with white markings
• Ensure seated tightly
• From auxiliary fuel pump (V393)
• Removing and Installing --> [ Auxiliary Fuel Pump ] Auxiliary Fuel Pump.
14 Fuel Pressure Sensor (G247), 100 Nm
• Removing and installing, refer to --> [ Fuel Pressure Sensor ] Service and Repair.
15 22 Nm
16 Tensioning Bracket
• Replace
• Note installation position --> [ Tensioning Bracket Installation Position ]
17 10 Nm
18 Injection Unit Cover
19 5 Nm
20 Injection Unit (Piezo Injector)
• Replace the following components and seals or O-rings each time they are removed: Tensioning bracket, copper disc, fuel injector duct O-ring and fuel injector return line O-ring.
• Replace the following components and seals or O-rings when replacing the fuel injector: Tensioning bracket, injection line, copper disc, fuel injector duct O-ring and fuel injector return line O-ring.
• When installing, the fuel injectors --> [ 5 High Pressure Lines ] and high pressure lines may only be installed on the same cylinder as before.
• Removing and installing, refer to --> [ Fuel Injection Unit ] Service and Repair
21 High Pressure Lines, 25 Nm
• Between high pressure fuel pump --> [ 10 Fuel High Pressure Pump ] and rail element (high pressure reservoir) --> [ 7 Rail Element (High Pressure Reservoir) ]
• Do not change angles of the high pressure line.
• Install without tension
Tensioning Bracket Installation Position
