Air Supply Unit, Servicing

Air supply unit, servicing

Assembly overview
^ The gray piston ring, installed before VIN WVGLG77L05D072104, is replaced by the brown piston ring.





1- Air supply unit, upper part
^ With cylinder head
2- Torx(R) bolts T30
^ Always replace
^ 5 Nm
3- Bracket
^ For air line
4- Seal
^ Always replace
5- Piston ring
^ Replace
^ Observe notes
6- Air supply unit, lower part

Piston ring, replacing

Special tools, testers and auxiliary items required





^ Torque Wrench VAG1410

Observe notes.

CAUTION!
^ Do not clean air supply unit using chemical cleaning agent or high-pressure cleaner.
^ Clean air supply unit using lint-free rag.
^ Make absolutely sure that no dirt enters the open air lines/air line connections, connectors and electrical connections.

Removing piston ring
- Remove air supply unit without solenoid valve block.





- Disengage connector - arrow - and disconnect it.





- Remove cable - 1 - from clip - arrow -.





- Remove bolts - arrows -.





- Remove cylinder head from piston and lay aside both components next to another.

Note: Make absolutely sure that the air line - 1 - is not damaged.





- Remove gasket - 1 - and clean contact surface on cylinder head.
- Pull piston - 2 - in - direction of arrow - toward TDC (Top Dead Center).
- Remove piston ring - 3 - from piston - 2 - without equipment, e.g. screwdriver.

Installing piston ring





- Place new piston ring onto piston, gap - arrow A - on piston ring must point toward outside.

Note:
^ Gap - arrow A - and anti-twist mechanism - arrow B - must align.
^ Piston ring is properly installed if anti-twist mechanism is visible in gap on piston ring - arrow C -.
^ Make sure not to overstretch piston ring.
^ Check piston ring play, piston ring must be able to be easily turned in both directions within anti-twist mechanism in gap of piston ring - arrow C - while doing so.





- Insert new gasket - 1 -.
- Push piston - 2 - with piston ring - 3 - opposite to - direction of arrow - toward BDC (Bottom Dead Center).





- Assemble upper and lower part, piston - 1 - must slip into cylinder head - 2 - while doing so.

Tab - arrow A - must be inserted into recess - arrow B -. They serve as an anti-twist mechanism.





- Retainers - 1 - must be positioned between upper part and lower part and at white markings of air line - arrows -.





- Tighten bolts - arrows - to tightening torque.





- Clip cable - 1 - in clip - arrow -.





- Connect connector - arrow -.
- Install air supply unit.

Tightening torque: