Fuel Rail: Service and Repair

13 53 158 Removing And Installing/Replacing High-Pressure Rail (N53, N54, N54T)


Special tools required:







WARNING:
Observe warning on cylinder head cover.
Disconnect negative battery terminal (risk of fire due to short circuit on removal).
Electric fuel pump starts up automatically each time door is opened.
Carry out installation work on fuel system only with coolant temperature below 40 °C.







IMPORTANT:
Wear full face guard and protective gloves.
Fuel can emerge spontaneously at high speed when the high pressure line is released.







IMPORTANT:
Adhere to conditions of absolute cleanliness when working on the high-pressure fuel system.
Introduced contaminants can cause malfunctions in the system.

- Do not allow any dirt particles or foreign bodies to get into the system.
- Remove all traces of dirt contamination before removing lines or separate components.
- Use only fluff-free cloths.
- Seal all fuel system openings with protective caps or plugs.







IMPORTANT:
When working on the oil, coolant or fuel circuit, you must protect the alternator against dirt contamination.
Cover alternator with suitable materials.
Failure to comply with this procedure may result in an alternator malfunction.







Necessary preliminary tasks:
- Disconnect pressure lines.
- N54 only:
Remove intake silencer housing.







Recycling:
Fuel escapes when fuel lines are detached.
Catch and dispose of escaping fuel.
Observe country-specific waste disposal regulations.







Unlock connector (1) and remove.
Pull the connector holder off the high pressure rail.
Remove all holders for the wiring harness from the high pressure rail.







Unlock connector (1) and remove.
Slacken nut (2).
Release screws (3) and remove high-pressure rail (4).







Installation of high pressure rail:
The installation of the high pressure rail is described separately from removal.







Install high pressure rail (4) while manually tightening screws (3) and nut (2).

NOTE:
- High pressure rail must still be displaceable on cylinder head.
- Nut (2) must be able to be screwed on easily by hand.

Push on connector for high pressure sensor (1).







Fitting pressure lines:
(Same procedure for all pressure lines)
Connect pressure line (1), tightening nuts hand-tight only in the process.

IMPORTANT:
Connect pressure line (1) without tension only.
To ensure distortion-free installation of the pressure line and to avoid damaging the thread, it must be possible for both nuts to be screwed on easily by hand.
If the nuts cannot be easily screwed on by hand, the injector must be turned into the installation position.

NOTE: Description of "Turning injector into installation position" in the following operation.







Only if one injector has to be turned into installation position:
- Release bolt a few turns until holding-down device (1) is slackened.
- Turn injector (2) in direction of arrow until nuts on pressure line can be easily screwed on by hand.
- To do so, engage spanner on hexagon head of injector (2) if necessary.
- Tighten nuts on pressure line hand-tight.

IMPORTANT:
Do not under any circumstances pull injector out of bore hole.
If the injector is pulled out of the bore hole, the PTFE sealing ring must be replaced.
Replacing PTFE sealing ring, refer to 13 53 310.







Tighten down screws (1).
Tightening torque 13 53 1AZ.
Tighten nut (2).
Tightening torque 13 53 7AZ.







Tighten down screw for hold-down device (1).
Tightening torque 13 53 5AZ .

NOTE: This operation is only necessary if one of the hold-down device has been slackened beforehand.







Adhere to tightening sequence:
- First tighten down nut (1) on injector.
- Then tighten down nut (2) on high-pressure rail.

When tightening nut (1) on injector, grip hexagon head of injector with wrench (3).
Tighten down nuts with special tool 37 1 151.
Tightening torque 13 53 8AZ .

Assemble engine.
Check fuel system for tightness.
Check function of DME.