2. Remove the fan and shroud, all belts, pulleys and damper.
3. Unscrew the camshaft sprocket bolt (photo).
12.3 Unscrewing the sprocket bolt
4. Remove the sprocket.
Attention! The sprockets have R (right) and L (left) marks indicating which sprockets belong to which camshaft. If both sprockets are removed, do not mix them up (photo).
The publication is reprinted from this resource NISSANBOOK
12.4 Marks y and L on camshaft sprockets
5. Carefully remove the oil seal (photo). Press in a new oil seal (photo).
12.5a Removing the oil seal
12.5b Pressing in the oil seal (the same device is used as for the crankshaft seal)
12.6 Orientation of the sprocket when installing on the camshaft
1. Installation mark; 2. Index; 3. Groove; 4. To the front of the engine; 6. Install the sprockets with the R and L indices facing outward (photo); 7. Tighten the sprocket bolt. The remaining operations are performed in reverse order