Instructions for working on fuel system

To prevent the high-pressure fuel pump from running while it is empty and to ensure that the engine starts quickly after parts have been renewed, it is important to observe the following:

• If fuel system components between fuel tank and fuel highpressure pump are removed or renewed, initial fuel filling must be carried out.
• If a fuel pump, fuel line (between fuel tank and fuel high-pressure pump) or fuel filter is removed or renewed
• Fuel system must be bled before starting engine for first time.
• If the high-pressure fuel pump is removed or renewed, the fuel system must be bled before engine is started for the first time.
• Initial fuel filling procedure ⇒ 1.3 Filling/bleeding fuel system.
• Clean tools and workbench etc. before working on injection system.
• Thoroughly clean all unions and adjacent areas before disconnecting.
• When removing components, seal all open connections immediately with suitable, clean protective caps.
• Do not remove sealing caps from components until immediately prior to installation. Removed components should be kept in new, sealable plastic bags (use the original new part packaging if possible).
• Before installation, check injectors and their fitting location visually; they must be undamaged and free of lint. Ensure that the injector bore is clean. If necessary, clean the injector shaft using a clean cloth.
• Do not damage it (no sharp-edged tools!)
• If high-pressure lines are not renewed, they must be labelled on removal. High-pressure fuel lines must always be re-installed in their original positions (i.e. on the same cylinder).
• Whenever injectors are removed and installed, always renew the following components and seals/O-rings: “bolt for clamping piece”, “copper seal”, “O-ring for injector bore”.
• The following components must also be renewed when an injector is replaced: “bolt for clamping piece”
• Always fit new copper seals for the injectors. Check all new O- rings for damage before installing. Lubricate O-rings lightly with assembly oil or clean engine oil before installing.

• Take care not to damage the injectors when removing the old copper seals.
• Align high-pressure lines stress-free. First tighten all unions hand-tight and then tighten to torque.
• Never attempt to reshape high-pressure fuel lines.
• When working on any parts of the high-pressure fuel system, tools may only be used for loosening and tightening pipe unions. All other components must always be removed and installed by hand without using tools or other equipment.
• Disassembling individual common rail components is not permitted.
• The components should be replaced as complete units if faulty.
• Never attempt to bleed the common rail system by loosening high-pressure components after starting the engine.
• No assembly work may be carried out on the CR system while the engine is running. In particular, do not open/loosen the high-pressure lines.
• Loosened cable ties must be secured in the same position on installation.
• Cut cable ties must be renewed and secured in the same position on installation.
• When the fuel system is open: Do not work with compressed air. Do not move vehicle unless absolutely necessary.
• Also ensure that no diesel fuel comes into contact with the coolant hoses. Should this occur, the hoses must be cleaned immediately. Damaged hoses must be renewed.