Renewing O-rings for unit injector: VW Touareg I 4.9 TDI (AYH, BKW, BLE, BWF, …)
Step-by-step renewing O-rings for unit injector for the VW Touareg I 4.9 TDI: 16 steps. What to remove, in what order, and what to check after.
Unit injectors on the Touareg I (7LA) with the AYH, BKW, BLE and BWF diesel engines carry three O-rings of different thickness, and leaking rings show up as fuel in the oil or hard starting. Renewing them means the injector comes out first; the rest is careful bench work. The old rings are levered out without scoring the grooves, the heat shield seal and clip are removed, and the seats are cleaned. Each new ring then goes on over its own assembly sleeve, T10056/1, /2 and /3, upper thick ring first, centre thin ring next, lower ring last. Success depends on using the sleeves rather than rolling rings over the edges, and on keeping each ring in the correct groove without twist.
🧭 Before you start
With the unit injector removed, prise out the old O-rings without damaging the seats, take off the heat shield seal and clip, and clean the grooves thoroughly. Fit the upper, centre and lower O-rings in turn using sleeves T10056/1, T10056/2 and T10056/3, removing each sleeve after use. Fit a new heat shield seal with its clip and reinstall the injector.
Fits: VW Touareg I (7L, 2002–2010)
Don't miss
- Always fit the O-rings with assembly sleeves T10056; without them the rings are easily cut.
- Ring thickness reduces towards the nozzle; check each ring goes in its correct groove.
- Do not let O-rings roll or twist as they slide on.
- Inspect the ring seats for burrs before fitting new rings.
- Renew the heat shield seal together with its securing clip.
Written for this job from the workshop steps below · TorqFix editorial.
📋 Procedure
- Remove unit injector .
- Lever old O-rings very carefully out of unit injector.
- Pay particular attention to ensure that seat of O-ring is not damaged by burrs. [Note: Always use assembly sleeves T10056 to fit the O-rings. There is a danger of damaging the O-rings if the sleeves are not used.Gradual introduction of O-rings without different coloured markings. Note the correct allocation of O-rings to grooves: the thickness of the rings reduces towards injector nozzle:Prevent O-rings from rolling when sliding them on. The O-rings must not be twisted in their seats in unit injector.]
- Pull heat shield seal off together with securing clip.
- Clean seating surfaces for O-rings on unit injector very carefully.
- Place assembly sleeve T10056/1 onto stop on unit injector.
- Push the upper, thicker O-ring carefully onto assembly sleeve and into seat on unit injector.
- Remove assembly sleeve.
- Place assembly sleeve T10056/2 onto stop on unit injector.
- Slide the centre, thinner O-ring carefully onto assembly sleeve and into seat on unit injector.
- Remove assembly sleeve.
- Place assembly sleeve T10056/3 onto stop on unit injector.
- Push the lower O-ring carefully onto the assembly sleeve and into the seat of the unit injector.
- Remove assembly sleeve.
- Fit new heat shield seal together with securing clip.
- Install unit injector .
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
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The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.