Fuel Delivery and Air Induction: Service and Repair

AH07.16-P-0002-01SM Notes About Common-Rail Components



Model 906 with engine 642.896/898/992/ 993, 651.955/956/957


The following procedures and notes must be observed for removal/installation of common-rail components.
- Carefully clean the working area on engine and required tools before beginning removal of common-rail components to be free of dirt and fluid.
- Arrange access to the working area through removal of disturbing engine attached parts.
- Do not eat, drink or smoke.
- Only use tools to loosen and tighten fasteners and high-pressure lines. All other assembly or disassembly procedures must be performed by hand and without an aid.
- Close off opened connections using suitable caps.
- Keep the container for assembly aid materials clean and seal or cover if not used.
- Mount sealing ring while moist (use assembly or engine oil). For vacuum and water hose use assembly aid material Palatinol N or soap water; for leak oil line use assembly aid material Palatinol N or diesel fuel.
- Remove cap by hand and only immediately before assembly.
- Do not bend high-pressure lines and install unstressed.
- Observe assembly note from manufacturer and specified tightening torques.
- Disassembly of common-rail components is not permissible. In the case of failure, completely replace the respective components with the exception of the fuel distribution rail.
- When replacing common-rail components use the caps from the new part on the removed part as soon as the new part is built-in.
- Do not lay any objects on the common-rail components; there is danger of unnoticed damage.
- After installing common-rail components, all connections are to be checked for leak tightness and the leak oil line possibly by hand for tight seating.

When observing the detailed procedures common-rail components, apart from high-pressure lines on some engines, can be installed a number of times. Nevertheless, avoid unnecessary disassembly. Sealing rings and stretch bolts must always be replaced.

Before starting the engine after assembly operations on the fuel system after driving until the fuel tank is empty the following should be observed:
- adequate filling of the fuel filter housing
- do not bleed the fuel system at the high-pressure connection
- if necessary actuate the starter for a long time without a break

For a running engine and within the first 30 s after switching off, no assembly operation should be conducted on the fuel system.
There is a danger of fuel escaping under high pressure. The engine should be run for a few minutes at a middle rotational speed for the subsequent leak test and then switched off again. Visually inspect the fuel system afterwards for leak tightness. In the case of leaks despite a correct tightening torque the common-rail components involved should be replaced.