Attention! Modification of the cylinder head is not allowed.
Attention! When dismantling the vacuum pump, turn it in the direction of the arrow, after unscrewing the bolts 1 (see sidebar in Figure 4.0).
Withdrawal
1. Disconnect the wire terminal «masses» (-) from the negative pole of the battery.
2. Drain the coolant.
3. Remove the front bumper (see relevant chapter).
4. Set the front cross member to the service position (see paragraphs 3.1-3.6).
5. Remove the timing belt from the camshaft gears (see relevant chapter).
6. Remove the gears from the camshafts.
7. Remove intake manifold (see relevant chapter).
Right cylinder head
8. Unscrew the mounting bolts (see arrows in illustration) and remove the right rear of the timing gear cover.
![](https://www.audimanual.ru/img/a6/2783.jpg)
4.8/ Unscrew the mounting bolts (see arrows) and remove the right rear of the timing gear cover
9. Unscrew the mounting bolts and detach the dipstick guide tube by pushing it up.
10. Disconnect from a head of the block of cylinders an exhaust manifold with a connecting pipe.
11. Unscrew the mounting bolts (see arrows in illustration) and remove the turbocharger heat shield.
![](https://www.audimanual.ru/img/a6/2784.jpg)
4.11. Unscrew the fastening bolts (see arrows) and remove the turbocharger heat shield
12. Unscrew union nuts and disconnect fuel lines of a high pressure from fuel atomizers, previously having designated fuel lines.
13. Disconnect the hoses of the turbocharger and the mechanical exhaust gas recirculation valve (see arrows in illustration).
![](https://www.audimanual.ru/img/a6/2785.jpg)
4.13. Disconnect the hoses of the turbocharger and the mechanical EGR valve (see arrows)
14. Remove the clamps (see arrows in illustration) and disconnect the air duct if the air filter has not been removed before.
![](https://www.audimanual.ru/img/a6/2786.jpg)
4.14. Remove fastening clamps (see arrows) and disconnect the duct
15. Disconnect plugs 1, 2 and 3, as well as plug 4 of the injection pump and plug 5 of the coolant temperature sensor (see illustration).
![](https://www.audimanual.ru/img/a6/2787.jpg)
4.15. Disconnect plugs 1, 2 and 3, as well as plug 4 of the injection pump and plug 5 of the coolant temperature sensor
16. Disconnect the glow plug power plugs and move the wiring harness away from the work area.
17. Disconnect the plug (see arrow in illustration), located on the right engine mount and move the wiring harness away from the work area.
![](https://www.audimanual.ru/img/a6/2788.jpg)
4.17. Disconnect the plug (see arrow), located on the right engine mount and move the wiring harness away from the work area
18. Release the plug (see arrow in illustration) injector needle stroke sensor from the holder and disconnect it.
![](https://www.audimanual.ru/img/a6/2789.jpg)
4.18. Release the plug (see arrow) injector needle stroke sensor from the holder and disconnect it
19. Disconnect the oil line from the turbocharger by unscrewing nut 1, and the oil line from the cylinder block by unscrewing nut 2 (see illustration).
![](https://www.audimanual.ru/img/a6/2790.jpg)
4.19. Disconnect the oil line from the turbocharger by unscrewing nut 1, and the oil line from the cylinder block by unscrewing nut 2
20. Unscrew bolts 2 and 3 and move hose 1 of the cooling system away from the place of work (see arrow in illustration).
![](https://www.audimanual.ru/img/a6/2791.jpg)
4.20. Unscrew bolts 2 and 3 and move hose 1 of the cooling system away from the place of work (see arrow)
21. Disconnect the fuel return line 1 from the fuel injectors and move the common fuel return line away from the job site (see illustration).
![](https://www.audimanual.ru/img/a6/2792.jpg)
4.21. Disconnect the fuel return line 1 from the fuel injectors and move the common fuel return line away from the work area
22. Unscrew the fastening nuts (see arrows in illustration 4.21) and remove the cylinder head cover.
23. Unscrew bolts of fastening of the right head of the block of cylinders in the sequence specified in an illustration, and remove a head. Lay the removed cylinder head on a soft pad so as not to damage the injectors and glow plugs.
![](https://www.audimanual.ru/img/a6/2793.jpg)
4.23. Unscrew bolts of fastening of the right head of the block of cylinders in the specified sequence
Left cylinder head
24. Unscrew the mounting bolts (see arrows in illustration) and remove the top 2, right 1 and left 3 parts of the rear timing cover.
![](https://www.audimanual.ru/img/a6/2794.jpg)
4.24. Unscrew the fastening bolts (see arrows) and remove the top 2, right 1 and left 3 parts of the rear timing cover
25. Remove the clamps (see arrows in illustration), unscrew bolts 1 and 2 of fastening and remove the pipeline of system of cooling.
![](https://www.audimanual.ru/img/a6/2795.jpg)
4.25. Remove fastening clamps (see arrows), unscrew bolts 1 and 2 of fastening and remove the pipeline of the cooling system
26. Cars with AFB, AKN engine. Disconnect from an exhaust manifold a reception pipe with the catalyst and remove an exhaust manifold together with a connecting pipe.
27. Cars with AFB, AKN engine. Disconnect the air pipe from the turbocharger.
28. Vehicles with AKE, AYM, BAU, BCZ, BDG, WON, BFC engines. Remove the pre-catalyst, then disconnect the exhaust pipe with the catalyst from the exhaust manifold and remove the exhaust manifold together with the connecting pipe.
29. Disconnect the plug 1 of the air conditioning compressor control valve (see illustration) and move the wiring harness away from the work area.
![](https://www.audimanual.ru/img/a6/2796.jpg)
4.29. Disconnect the plug 1 of the air conditioning compressor control valve and move the wiring harness away from the place of work
30. Disconnect the plug (see arrow in illustration) intake manifold air pressure sensor, release from the holder and move the wiring harness away from the place of work.
![](https://www.audimanual.ru/img/a6/2797.jpg)
4.30. Disconnect the plug (see arrow) intake manifold air pressure sensor
31. Disconnect the glow plug power plugs, then disconnect the injection pump plug.
32. Vehicles with ARV, AKE, AKN, AYM, BAU, BCZ, BFC engines. Unscrew the mounting bolts and remove the mechanical valve 1 of the exhaust gas recirculation system (see illustration).
![](https://www.audimanual.ru/img/a6/2798.jpg)
4.32. Unscrew the mounting bolts and remove the mechanical valve 1 of the exhaust gas recirculation system. Vehicles with AFB, AKE, AKN, AYM, BAU, BCZ, BFC engine
33. Vehicles with AFB, AKE, AKN, AYM, BAU, BCZ, BFC engines. Remove clamps 1 and 2 of fastening and disconnect the hoses of the cooling system from the nozzles by unscrewing the bolt 3 (see illustration).
![](https://www.audimanual.ru/img/a6/2799.jpg)
4.33. Remove fastening clamps 1 and 2 and disconnect the cooling system hoses from the pipes by unscrewing bolt 3. Cars with AGV, AKE, AKN, AYM, BAU, BCZ, BFC engines
Attention! Illustration 4.33 shows the cooling system hoses with the engine removed.
34. Remove the bolt (see arrow in illustration) and disconnect from a head of the block of cylinders a branch pipe of system of cooling.
![](https://www.audimanual.ru/img/a6/2800.jpg)
4.34. unscrew the bolt (see arrow) and disconnect the cooling system pipe from the cylinder head
35. Disconnect the fuel return lines 1 from the fuel injectors and move the common fuel line away from the work site (see illustration).
![](https://www.audimanual.ru/img/a6/2801.jpg)
4.35. Disconnect the fuel return lines 1 from the fuel injectors and move the common fuel line away from the work area
36. Unscrew the nuts (see arrows in illustration 4.35) fixing the cover of the left cylinder head and remove the cover.
37. Unscrew bolts of fastening of a head of the block of cylinders in the sequence specified in an illustration, and remove a head from the block. Place the removed cylinder head on a soft pad so as not to damage the glow plugs and fuel injectors.
![](https://www.audimanual.ru/img/a6/2802.jpg)
4.37. Remove the cylinder head bolts in the sequence shown and remove the cylinder head from the block
Installation
Installation of a head of the block of cylinders is made in sequence, return to removal.
38. Check up a condition of a head of the block of cylinders and be convinced of absence of cracks and gouges.
39. Clean the threads of the holes for the cylinder head bolts. These holes must be free of oil or other contaminants. If necessary, blow out the holes with compressed air or clean with a screwdriver wrapped in rags that absorb liquid. Oil can be collected from the holes with a grease gun. If this is not done, then when the mounting bolts are screwed in, excess pressure will be created in the holes, which can lead to a rupture of the cylinder block or an incorrect tightening torque of the bolts.
40. Remove the remnants of the old seal from the surface of the cylinder block and head using a plastic scraper. Keep dirt and seal residues out of the cylinder bores. Close the cylinder bores with rags.
Attention! Cleaning of sealing surfaces with a metal brush or other metal tool is not allowed.
41. Check the cylinder head for distortion, deformation or warpage using a feeler gauge and steel ruler (see illustration). The maximum allowable warping of the head should not exceed 0.1 mm. Modification of the cylinder head is not allowed.
![](https://www.audimanual.ru/img/a6/2803.jpg)
4.41. Check the cylinder head for warping, deformation, or warping with a steel ruler
42. Inspect the removed cylinder head gasket and, if the pistons, connecting rods or crankshaft have not been replaced, install a new gasket of the same thickness as the previous one (see illustration). Marking inscription «Oben/Top» on the gasket, when laying it, it must be directed upwards, towards the cylinder head.
![](https://www.audimanual.ru/img/a6/2804.jpg)
4.42. Cylinder Head Gasket: 1 - marking holes; 2 - article number according to the spare parts catalog; 3 - manufacturer's code/marking
43. Cylinder head gasket (see illustration 4.42) can have up to three marking holes, depending on the thickness, which, in turn, depends on the protrusion of the pistons. Measure the protrusion of the pistons from the cylinder block using special tools to select the correct thickness of the head gasket (see illustration). To do this, turn the crankshaft and alternately set the pistons to TDC. Piston protrusion is calculated as the average of the measurement results at two points.
![](https://www.audimanual.ru/img/a6/2805.jpg)
4.43. Measure the protrusion of the pistons from the cylinder block to find the correct head gasket thickness
Piston protrusion, mm | Number of marking holes on the gasket |
0,39-0,49 | 1 |
0,49-0,54 | 2 |
0,54-0,65 | 3 |
Attention! The maximum protrusion difference between two adjacent pistons must not exceed 0.10 mm.
Attention! A new cylinder head gasket must be removed from the packaging immediately before installation.
44 Tighten the cylinder head bolts in several passes in the sequence shown in the illustration:
- 1st pass - tighten the bolts with a force of 35 Nm;
- 2nd pass - tighten the bolts to 60 Nm;
- 3rd pass - tighten the bolts by 90°;
- 4th pass - Tighten the bolts 90°.
![](https://www.audimanual.ru/img/a6/2806.jpg)
4.44. Tighten the cylinder head bolts in several passes in the sequence shown
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