477755 Replacing vacuum line for brake booster (section at engine)
WM 477755 Replacing vacuum line for brake booster (section at engine)
Tools
Information
Removal and installation instructions relate to the vacuum line (vacuum hose/vacuum line assembly) -1- in the engine compartment.
The vacuum line (vacuum hose/vacuum line assembly) -1- is secured on one side at the tandem pump of the left camshaft (with two M6 Torx screws) and is fitted on the other side at the connection point (plug-in coupling) -2- for the brake-booster vacuum line on the vehicle side.
Brake-booster vacuum line (section at engine)
Preliminary work
1. Remove air cleaner housing -3- and pressure pipe -4- (-> 24251900 Removing and installing air cleaner housing). The instructions for removing the air cleaner housing -3- also covers removing the pressure pipe -4-.
Air cleaner housing and pressure pipe
Component overview
Component overview
Removing vacuum line
1. Pull adapter -2b- - or hose piece if an adapter -2b- is not used - together with the thin vacuum line out of the branch piece of the vacuum line -1-.
Disconnect vacuum line -1- from the vacuum line on the vehicle side in area -2- at the plug-in coupling. To do this, remove the retainer -2a- and pull the vacuum line out of the plug-in coupling while releasing it at the same time.
Vacuum line connections
2. Release vacuum line -1- from combination holder -3- (open combination holder -3- ).
3. Unclip lines from the retaining clip -4-.
4. Remove vacuum line -1- at the tandem pump -7-. To do this, loosen the two Torx screws -5 and 6- (Torx E10) -from the underside when the vehicle is raised-. Counter at the hexagon on the combination screw behind it (behind the holder) when loosening the Torx screw -5-. You only need to counter if a combination screw is fitted under the holder (introduced only in the current model series).
Press vacuum line -1- out of the tandem pump -7-.
Vacuum line at tandem pump
5. Lower the lifting platform and remove vacuum line (take it out of the engine compartment). Important: Before removing the vacuum line, take note of the installation position between the various hoses and lines for subsequent installation!
Installing vacuum line
1. Fit a new retaining clip -4- at the correct position -see illustration- on the new vacuum line -1-. Use the correct vacuum line -1- as per Spare Parts Catalogue.
Fitting cable holder
2. Fit new vacuum line -1- (feed it from the engine compartment towards the tandem pump). Do not pull the protection cap off the new vacuum line -1- (at the connection point to the tandem pump) yet (danger of soiling). Observe the installation position between the various hoses and lines!
Vacuum line connections
2.1. Fit the vacuum line -1- into the plug-in coupling on the vacuum line on the vehicle side in area -2-. Fit retainer -2a-.
2.2. Check that adapter -2b- - if one is fitted - is at the correct position (installation position). A hose piece is often used instead of the adapter -2b-.
The following applies if the adapter -2b- is fitted:
Position of adapter
The adapter -2b- is fitted correctly in the connection and is at the correct installation position if both longitudinal bars on the adapter -2b- (can be checked both visually and by touch) are located on the side of the thin vacuum hose.
CAUTION
Be careful when pulling the adapter off the pressure line: More time and effort is involved if the adapter is pulled off the vacuum line without countering it.
- If you do not counter at the vacuum line, the vacuum line can become loose at the change-over valve (installed between the intake system and rear wall of body). This prevents wastegate control. As a result:
- The throttle valve may become damaged.
- The vehicle jerks slightly when the accelerator is released.
- Check Engine light comes on/fault code P2181 appears in the DME fault memory (Tiptronic only).
-> Pull the adapter off the vacuum line while countering using sufficient force.
-> Do not kink or bend the vacuum line.
If not installed at the correct position, pull the adapter -2b- out of the thin vacuum line, turn it around and slide it on to the thin vacuum line with the longitudinal bar side first.
2.3. Insert adapter -2b- or hose piece (if no adapter -2b- is used) into the vacuum line -1-.
Vacuum line connections
3. Raise the lifting platform. Fit vacuum line correctly at the tandem pump. Replace the two micro-encapsulated (self-locking) fastening screws -5 and 6- whenever they have been loosened.
Vacuum line at tandem pump
3.1. Pull protection cap off the new vacuum line. Coat O-ring lightly with engine oil and insert new vacuum line -1- into the tandem pump. Caution: Risk of damaging O-rings!
3.2. Screw in new micro-encapsulated (self-locking) fastening screws -5 and 6- and tighten to 10 Nm (7.5 ftlb.). Counter at the hexagon on the combination screw behind it (behind the holder) when tightening the Torx screw -5-. You only need to counter if a combination screw is fitted under the holder (introduced only in the current model series). Observe position (fastening point) for short screw -5- and long screw -6-.
4. Secure vacuum line -1- to the combination holder -3-.
Clip line into the retaining clip -4-.
Vacuum line connections
Subsequent work
1. Install pressure pipe -4- and air cleaner housing -3-. The instructions for installing the air cleaner housing -3- also covers installing the pressure pipe -4-. -> 24251900 Removing and installing air cleaner housing.
Air cleaner housing and pressure pipe
2. Check vacuum using tester 9160/1.
2.1. Tester 9160/1 (pressure gauge) must be connected. To do this, pull the adapter -2b- (or hose piece if an adapter -2b- is not used) together with the thin vacuum line out of the branch piece -2- of the vacuum line -1-.
Checking the vacuum
2.2. Tester 9160/1 must be connected (plugged in) to the branch piece -2-.
2.3. Start the engine and allow it to idle (engine speed is 650. 750 rpm/ambient temperature is 20°. 25° C). After a waiting time of approx. 10 seconds, read off the existing vacuum on the pressure gauge. Minimum value: 650 mbar.
2.4. Then remove the tester 9160/1 and re-connect the adapter -2b- (or hose piece, if no adapter -2b- is used) to the branch piece -2-.