Work on the gas distribution mechanism (Audi Q7-4L-D)

Caution: After installing the camshafts, wait at least 30 minutes before starting the engine to allow the hydraulic lifters to settle. Otherwise, the valves may hit the pistons.

1. The installation details of the timing components are shown in the illustration using the example of the left cylinder head.



2. Processing of valves and their seats, except for lapping, is not permitted.

3. When working with the timing belt, arrange the removed parts so that they can then be installed in their original places.

Replacing camshaft seals

4. Remove the fuel injection pump drive toothed belt (see Chapter 4) and the camshaft gear(see paragraphs 9-10 of Section 11).

5. Unscrew the inner part of puller #2085 three turns from the outer part so that it is flush with the outer part, then unscrew the inner part 3 turns and lock with the knurled bolt.

6. Lubricate the threaded head of the puller and, pressing hard, screw it into the seal as far as possible (see illustration).



Loosen the knurled bolt and remove the seal by rotating the inner part of the puller. Clamp the puller in a vice and remove the seal.

7. Clean the mating and sealing surfaces. Press the new oil seal onto the camshaft until it stops using the T10053 bushing and the M10x1.25x40 bolt (arrow in the illustration).





8. Install the camshaft timing gear and timing belt.

Removal and installation the camshafts of the left cylinder head

Note: Special tools are required to install the camshafts.

9. Remove the left upper timing chain from the camshafts (see Section 9).

10. On BUG/BUN engines, remove the upper section of the intake manifold (see Chapter 4).

11. Remove the fuel injection pump drive toothed belt (see Chapter 4) and the camshaft gear (see paragraphs 9-10 of Section 11).

12. Remove the left cylinder head cover (see Section 11).

13. On CASA/CASB engines, loosen the union nut (1 in the illustration) high pressure fuel line, unscrew the bolts (arrows) and remove the fuel distribution line from the left cylinder head.



14. Loosen the camshaft bed fasteners in the following sequence: (18-1 in the illustration).





Completely remove the fasteners and carefully remove the bed and shafts, avoiding damage to the rocker arms and hydraulic lifters. If necessary, remove the rocker arms and hydraulic lifters.

15. Make sure that the axle bearings in the shaft bed are not damaged.

16. Seal the holes to prevent dirt from entering the lubrication system and remove any remaining sealant from the cylinder head and shaft bed. Use a plastic drill brush attachment. Clean mating surfaces from oil and grease. Lubricate the working surfaces of both camshafts.

17. Assemble the T40094 tool by inserting the -/2 support into position "A" and the -/1 support into position "D" (see illustration).



18. Place the exhaust shaft (1 in the illustration) into the T40094/1 and -/2 supports and turn it so that it can be locked at TDC with the locking device (arrow).





Install the T40096 device onto the shaft teeth so that the two levers of this device sit on the two halves of the gear (one lever for each half). Secure the T40096 tool with a knurled bolt so that the tooth surfaces are aligned.

19. Place the intake shaft (2 in the illustration) into the T40094 device, aligning the centering pin (3) with the cutout.



Move the exhaust shaft (1) towards the intake shaft in the direction of the arrows until the gears engage. Make sure the semi-circular recesses in both camshafts are facing outward.

20. Install the camshafts on their bed (1 in the illustration).



All bearings must fit onto the shafts. Install the T40095 tool onto the camshafts (align the bracket arms as required and tighten the knurled nuts (2)). Create tension on the camshafts by tightening the knurled nuts (3).

21. Make sure that the centering pins are present in the cylinder head (see illustration).



22. Turn the camshaft bed over and apply a bead of sealant to its clean mating surface as shown in the illustration.



The sealant should completely fill the groove and protrude 1.5-2.0 mm. After applying the sealant, the bed should be installed within 5 minutes.

Note: For clarity, the bed is shown without camshafts.

23. Make sure all rocker arms are in contact with the valves and hydraulic lifters. Install the bed together with the shafts and devices T40095 and -96 on the cylinder head and tighten the bolts/nuts in the sequence (1-18 in illustration 12.14). Tighten the fasteners by hand first, so that the bed is in full contact with the cylinder head. After this, tighten the fasteners to 9 Nm.

24. Remove tools T40095 and -96, replace the camshaft oil seal (see the relevant subsection above) and install the remaining parts.

Removal and installation the camshafts of the right cylinder head

Note: Special tools are required to install the camshafts.

25. Remove the right upper timing chain from the camshafts (see Section 9).

26. Remove the right cylinder head cover (see Section 11).

27. For CASA/CASB engines, perform the steps described in paragraphs 28-30. For BUG/BUN engines, proceed to paragraph 31.

28. Disconnect the feed (1 in illustration 4.27) and return (2) fuel lines from the air intake chamber dividing panel.

Note: Fuel may remain hot for some time after the engine is turned off. When disconnecting fuel lines, wrap the connection with a thick layer of cloth and slowly disconnect.

29. Remove the union nuts (1 and 2 in illustration 11.43), unscrew the bolts and move the fuel distribution line to the side without disconnecting the fuel hoses.

30. Remove the wiring (arrow in illustration 11.39) to the side.

31. Loosen the camshaft bed fasteners in the following sequence: (17-1 in the illustration).



Completely remove the fasteners and carefully remove the bed and shafts, avoiding damage to the rocker arms and hydraulic lifters. If necessary, remove the rocker arms and hydraulic lifters.

32. Follow the steps described in paragraphs 15-16.

33. Assemble the T40094 tool by inserting the -/2 support into position "B" and the -/1 support into position "C" (see illustration 12.17).

34. Place the exhaust shaft (1 in the illustration) into the T40094/1 and -/2 supports and turn it so that it can be locked at TDC with the locking device (arrow).



35. Place the intake shaft (2 in the illustration) into the T40094 device, aligning the centering protrusion (3) with the shaft groove.



Install the T40096 tool onto the teeth of the intake shaft so that the two arms of this tool sit on the two halves of the gear (one lever for each half). Secure the T40096 tool with a knurled bolt so that the tooth surfaces are aligned. Move the exhaust shaft (1) towards the intake shaft in the direction of the arrows until the gears engage. Make sure the semi-circular recesses in both camshafts are facing outward.

36. Install the camshafts on their bed (1 in the illustration).



All bearings must fit onto the shafts. Install the T40095 tool onto the camshafts (align the bracket arms as required and tighten the knurled nuts (2)). Apply tension to the camshafts by tightening the knurled nuts (3). Make sure the centering pins are present in the cylinder head (see illustration 12.21)

37. Turn the camshaft bed over and apply a bead of sealant to its clean mating surface as shown in the illustration. The sealant should completely fill the groove and protrude 1.5-2.0 mm. After applying the sealant, the bed should be installed within 5 minutes.

Note: For clarity, the bed is shown without camshafts.

38. Make sure all rocker arms are in contact with the valves and hydraulic lifters. Install the bed together with the shafts and devices T40095 and -96 on the cylinder head and tighten the bolts/nuts in the sequence (1-17 in illustration 12.31). Tighten the fasteners by hand first, so that the bed is in full contact with the cylinder head. After this, tighten the fasteners to 9 Nm.

39. Remove tools T40095 and -96, replace the camshaft oil seal (see the relevant subsection above) and the front sealing plug in the right cylinder head. Install the remaining parts.

Checking hydraulic compensators

Note: Maintenance of hydraulic compensators is not provided. Valve noise immediately after starting the engine does not indicate a malfunction.

40. Start the engine and wait until the coolant temperature rises to approximately 80°C. Increase the engine speed to 2500 rpm for approximately 2 minutes. If necessary, take a test drive.

41. If after this the hydraulic lifters continue to make noise, determine which of them are faulty, as described below.

42. Remove the cover of the corresponding cylinder head (see Section 11).

43. Insert the guide pin with a smaller diameter (2 in illustration 4.73a) into the T40058 adapter. Using this adapter, turn the crankshaft clockwise (see illustration 4.73b), so that the cam for the hydraulic compensator being tested is facing upwards.

44. Press on the rocker arm (see illustration) and determine the gap between the cam and the hydraulic compensator: if it is possible to insert a 0.20 mm thick feeler gauge into this gap, replace the hydraulic compensator (see the subsection "Removing and installing camshafts" above).



45. After checking, install the cylinder head cover.

Replacing valve stem seals

46. To replace the valve stem seals, remove the camshafts and rocker arms with hydraulic compensators (see the relevant subsection above).

47. Set the piston of the corresponding cylinder to BDC and remove the glow plugs (see Chapter 5).

48. Use the tools shown in the illustration to compress the valve spring.



To prevent the valve from falling into the cylinder, supply air to it through the spark plug hole under a pressure of at least 6 bar (if the work is performed without removing the cylinder head).

49. When installing valve stem seals, use the plastic bushings included in the kit.

(Information obtained from this resource: AUDImanual)