Sprockets and chain tensioners — removal, inspection and installation (BMW 3 Series E46)

Camshaft Sprockets

1. Removal, inspection and installation of sprockets is described in paragraph 7 as part of the secondary chain removal and installation procedure.

Crankshaft sprocket

Removal

2. The camshaft drive sprocket is combined with the oil pump drive sprocket. On some models, the sprocket may be pressed onto the crankshaft nose.

3. Remove the primary chain as described in paragraph 7.

4. Remove the sprocket from the nose of the crankshaft. If the sprocket is pressed onto the shaft, use a three-jaw puller. To cover the threaded hole for the hub mounting bolt in the center of the shaft, temporarily screw a bolt into the hole. Remember which side of the sprocket faces outward so that you can install it correctly later,

5. After removing the sprocket, check whether the key is holding well on the shaft nose. If not, remove it and save it.

Inspection

6. Inspection of sprockets is described in paragraph 7.

Installation

7. Insert the key into the shaft groove (if the key has been removed).

8. Place the sprocket on the shaft nose. If the sprocket was installed using a press fit, heat it to 150°C before installing the sprocket. Do not exceed this temperature, otherwise the sprocket material will lose its strength characteristics.

9. After heating the sprocket, align its groove with the key and press the sprocket onto the shaft using a pipe of suitable diameter.

Warning! If the sprocket has been heated, be careful - the metal may remain hot for a long time.

10. Install the primary chain as described in paragraph 7.

Secondary Target Tensioner

Removal

11. Remove the secondary chain as described in paragraph 7.

12. Remove the bolts and tensioner housing from the cylinder head (see fig. 7.28).

13. Pull out the locking rod that held the plunger in the depressed position, remove the plunger and spring (Fig. 8.13).

Inspection

14. Inspect the tensioner and replace it if necessary. Inspect the plunger and its bore for wear and damage. Inspect the tensioner spring and check its condition. Inspect the working surface of the tensioner shoe for wear. Replace worn or damaged parts.

15. When installing the plunger, keep in mind that after the tensioner is installed in place, the cutout in the plunger should be facing the right side of the engine.

Installation

16. Install the tensioner in place and securely tighten its mounting bolts.

17. Insert a rod or drill to secure the tensioner in the depressed position.

18. Install the secondary circuit as described in paragraph 7.

Primary tensioner

19. The removal and installation of the tensioner is described in paragraph 7 as part of the primary chain removal and installation procedure.