Front Door Latch: Service and Repair

51 21 090 - Removing and installing/replacing door lock in left or right front door





Special tools required:
- 51 2 190 51 2 190 Door Lock Tensioner





Necessary preliminary tasks:
- Remove door window glass Service and Repair
- Release power window unit Service and Repair in rear area only





Disconnect Bowden cable at bottom (1) and top (3) from door lock (2).

Important!
Bowden cable must be correctly located in mounts on door lock (2).
Seal (4) must be correctly positioned on Bowden cable.

Note:
The operations for "Removing Bowden cable from door lock" end here.





Unlock plug connection (1) at lugs (2) and detach from door lock (3).
Unclip locking rod (4) from door lock (3).





Important!
Do not damage door lock seal during removal.

Release screws (1).

Remove door lock (2) from inside.

Important!
To avoid leaking and electrical malfunction:
Pull door lock (2) with special tool into corner (3), see Figs. R51 3381 and R51 7594.





Driver's door only:

Installation:
Insert inside door lock (1) correctly into paddle (2) of lock cylinder (3).





Installation:
Seal (1) on door lock (2) must not be damaged.





Installation:
- Install door lock and insert screws (1), do not tighten down.
- Slide special tool 51 2 190 51 2 190 Door Lock Tensioner into opened rotary latch until latch engages in first stage.





Installation:
- Pretension door lock (1) with knurled screw (2) until special tool 51 2 190 51 2 190 Door Lock Tensioner just contacts corner points (3).

Important!
To tension door lock (1), it is only permitted to turn knurled screw (2) by a further 1 to 1.5 turns (max.) (risk of damage).
Door lock seal must rest uniformly on inner door plate (water ingress).

- Tighten down door lock screws, tightening torque 51 21 1AZ 51 21 Front Door Locks.