Note. You can purchase both new and remanufactured cylinder heads. Keep in mind that special tools will be required for disassembly and inspection, and new parts will not always be in the store immediately. Thus, it may be more practical to purchase a remanufactured head than to disassemble, inspect and rebuild the old one.
Disassembly
1. Remove the cylinder head from the block as described in part A or B this chapter. Remove the camshaft sprocket as described in part A or B of this chapter.
2. On diesel models, remove the injectors and glow plugs (see chapters 4B or 5V).
3. If necessary, remove the cooling system outlet flange along with the gasket/O-ring.
4. On AHL engines, unscrew the temperature sensor from the cylinder head.
5. It is very important when removing the components to group them together and keep them together to facilitate installation. If they are installed in the wrong place, increased wear is possible. Lay out the groups of components in plastic bags - mark the containers, for example: No. 1 outlet, No. 2 inlet, etc. (pic. 6.5). Cylinder #1 is on the timing belt side.
6. On the covers of the camshaft bearings there are manufacturer's marks, if for some reason they are not visible, apply your own with a scriber when removing them.
7. The camshaft bearing caps are removed as follows.
Engines ADR, AFY, AEB, AJL
8. At the front of the camshaft, remove the Hall sensor, remove the bolt from the camshaft, remove the cone washer and the Hall sensor plate.
9. The automatic camshaft phase adjuster must be blocked before removal. Audi mechanics use special tool 3366 for this (pic. 6.9, a). You can make a similar DIY tool out of a threaded stud, nut, and a small metal plate to squeeze the regulator. For insurance, tie a homemade tool with a plastic tie (pic. 6.9, b, c).
10. Line up the chain and sprockets behind the arrows on the rear camshaft bearing caps and mark the sprocket chain. Please note that the distance between the two marks must be equal to 16 chain rollers. The mark on the exhaust camshaft is slightly offset towards the center of the cylinder head.
11. Loosen cap bolts 3 and 5, then 6 on both camshafts (pic. 6.11).
Pic. 6.11. Cylinder head components (engines ADR, AFY, AEB, AJL): 1. Camshaft sprocket bolt; 2. Camshaft sprocket; 3. Oil seal; 4. Cylinder head; 5. Oil seal; 6. Valve spring; 7. Upper valve spring seat; 8. Crackers; 9. Hydraulic pusher; 10. Intake camshaft; 11. Intake wheel support cover; 12. Front combined support cover; 13. Exhaust camshaft; 14. Support cover, exhaust camshaft; 15. A bolt of fastening of a cover of a support of a cam-shaft; 16. Drive chain; 17. Automatic camshaft phase adjuster; 18. Rubber seal; 19. Semicircular rubber seal; 20. Exhaust valve; 21. Inlet valve; 22. Oil seal; 23. Hall sensor ring; 24. Conical washer; 25. Ring bolt; 26. Hall sensor; 27. Hall sensor mounting bolt
Note: The caps are numbered from the back of the cylinder head, #6 is a combination cap that fits on both camshafts.
12. Turn away bolts of fastening of a regulator of a phase of a cam-shaft.
13. Gradually loosen cap screws 4 and 2 on both camshafts, remove both camshafts from the cylinder head together with the automatic chain tensioner (pic. 6.13).
14. Unhook the regulator from the chain and remove the chain from the camshaft sprockets. Remove seals from camshafts (pic. 6.14).
Engines ADP, AHL, 1Z, AFF, AFN, ANN, AHU
15. Loosen the nuts of the covers of supports 5, 1 and 3, then covers 2 and 4 (pic. 6.15). Loosen the nuts in a diagonal sequence half a turn per pass until they can be removed by hand. Keep the covers in the correct order for their installation.
Pic. 6.15. Cylinder head components (engines 1Z, AHU, ANN. AFN and AFF): 1. Camshaft support cover; 2. Nut; 3. Camshaft; 4. Key; 5. Camshaft sprocket bolt; 6. Hydraulic pusher; 7. Upper valve spring seat; 8. Valve spring; 9. Valve stem seals; 10. Lower valve spring seat; 11. Guide sleeve; 12. Valves; 13. Semicircular seal; 14. Camshaft oil seal; 15. Cylinder head casting
Note: The covers are numbered 1 to 5 starting from the timing belt.
16. Remove the oil seal from the camshaft and discard it, a new one is required for installation (pic. 6.16).
17. Carefully remove the camshaft from the cylinder head, holding it horizontally by the ends so as not to damage the bearings.
All engines
18. Remove the hydraulic pushers and lay them upside down so that oil does not leak out (pic. 6.18). It is recommended to keep the tappets immersed in oil for the duration of the head repair. Remember the installation of each pusher in order to install them in their places during assembly to avoid increased wear.
19. Turn the head over and lay on its side. valve spring compressor ("cracker") squeeze them one at a time to take out the crackers. If the top plate "burned", hit the top heel of the compressor with a hammer (covered with a rag so that the crackers would not suddenly scatter), to free her (pic. 6.19, a, b).
Note: On 20-valve engines, the opening to access the intake valves is much smaller than the exhaust valves - the standard compressor may be too large If the Audi/VAG tool is not accessible. can be made homemade from a suitable nut, washer and metal bars welded together (pic. 6.19, a, b).
20. Release the compressor and remove the spring seat, valve spring (gasoline engines) or twin valve spring (diesel engines) (pic. 6.20, a, b).
21. Pliers or a special puller (convenient collet) pull the caps off the guide bushings, then (on diesel engines) remove the lower spring seat. Remove the valve from the valve seat side. Repeat the procedure for the rest of the valves (pic. 6.21, a-c).
Cleaning
22. Scrape off all traces of the old gasket from the cylinder head. Scrape off any carbon deposits from the combustion chambers and passages, being careful not to scratch them. Do not use sandpaper coarser than 100, then wash the head thoroughly with kerosene or other suitable solvent.
23. Scrape off any deposits from the valves. To facilitate the work, you can use a round wire brush with an electric or pneumatic drive.
24. If the head is very. dirty, it needs to be washed with steam. After washing is complete, dry the head thoroughly, making sure all oil and water passages are clean. Throw away the seals - new ones are required for assembly.
Examination
Cylinder head
Note: Valves and cylinder head cannot be repaired on diesel engines (valves can only be ground in, defective components are replaced with new ones.
25. Carefully inspect the head for cracks, visible signs of coolant leaks and other damage. Pay special attention to the areas around the valve seats and spark plug holes. If cracks are found between the valve seats, Audi claims that the head can be used if the cracks are no more than 0.6 mm wide. If more serious damage is found, the head must be replaced.
26. Minor seat burns can be removed by lapping the valves as described below. Serious burnouts of the saddle require their milling, however, this work should be entrusted to specialists.
27. Using a steel ruler and a set of flat probes, inspect the head for the absence of curvature of the connector surface with the block in several places (pic. 6.27). Compare the obtained measurements with the data given in Specifications. On gasoline engines, if necessary, the head can be ground without going beyond height specified in Specifications.
28. Minimum allowable head heights are given in Specifications.
Camshaft
29. Inspect the cams and camshaft bearing journals for obvious wear. Their surfaces should look smooth and semi-shiny. Examine any surfaces that appear excessively shiny - they may be worn. There should be no scratches, burrs, etc. If the hardened surface of the camshaft is worn, further wear will avalanche. A worn camshaft must be replaced.
Note: If the tops of the cams are worn, inspect their corresponding tappets - they may also be worn.
30. If provided, inspect the distributor drive gear. Excessive play in the drive indicates a worn gear and leads to incorrect ignition timing.
31. If there are discolorations on the friction surfaces of the camshaft, there may have been overheating in these places, most likely due to a lack of sufficient lubrication. Overheating can cause the shaft to bend - lay the shaft on prisms and check its runout in the central journal. If the beat exceeds the allowable specifications, the shaft must be replaced.
32. To measure the axial clearance of the camshaft, install the camshaft in the cylinder head, install the first and last support caps, tighten their fastening nuts to the prescribed torque for the first stage. Rest the leg of the dial indicator against the end of the shaft from the side of the timing belt, securing the device on the head. Move the camshaft all the way to one end and reset the scale. Now move the camshaft all the way to the other end of the head and read the indicator. Move the shaft again until it stops and make sure the dial is set to zero (pic. 6.32).
Note: When measuring, there should be no pushers in the head.
33. Compare the received data with the Specifications. If the gap is increased, both the camshaft and the cylinder head may be to blame. Worn parts must be replaced.
34. Now you need to measure the clearance in the camshaft bearings. The first method is hard to reach (due to the cost of the tool), is as follows. Without installing the camshaft, install the covers of all supports, then measure all the inner diameters of the bearings of the supports with an inside gauge. The next stage is the measurement of all diameters of the shaft journals with a verified micrometer. Subtracting the second results from the first results will give the value of the gap in each neck.
35. The second method, more accurate, is to use a plastic measuring rod "Plastigauge". This method can be even more difficult to access - "Plastigauge" very difficult to acquire. But, the method is as follows.
36. Make sure that the shaft and bearing surfaces of the supports in the head are completely clean. Lay the camshaft on a dry head.
37. Lay the cut "Plastigauge" on the top of each neck, placing it parallel to the axis of the shaft.
38. Install the camshaft bearing caps into the head and tighten them sequentially in a diagonal sequence to the prescribed torque.
Note: If cap fasteners are to be tightened in multiple stages, tighten them to the first stage torque only. Do not rotate the camshaft while measuring. otherwise you will get incorrect results.
39. Unscrew the mounting nuts of the supports and carefully remove the covers vertically upwards so as not to disturb "Plastigauge". Flattened pieces of plastic should remain on the necks.
40. Attach the palette that comes with "Plastigauge" to the segments and measure their width - calculate the gap on the scale.
41. Compare the obtained measurements with the data given in Specifications. If the gap exceeds the allowable, the camshaft and cylinder head must be replaced.
42. On DOHC engines, clearances are measured on both camshafts.
43. Finally, remove the bearing caps and camshaft, remove any plastic residue that has stuck to it.
Valves and related components
Note: On all engines, valve discs cannot be machined, they can only be lapped.
44. Check the valves visually for wear. There should be no changes in the diameters of the rods, burrs and deep scratches on them. Using a micrometer, measure the diameter of the valve stem in several places along the entire length (pic. 6.44).
45. Valve plates should not have cracks, burnouts and deep sinks. Slight pitting on the work bevels can be removed by lapping during assembly as described below.
46. The heel of the valve stem must not have excessive wear and spalling of the metal; these defects are possible with faulty hydraulic pushers.
47. Insert the valve into your guide sleeve and fasten a dial gauge next to the poppet. Slide the valve out of the sleeve until its heel is flush with the end of the sleeve. Measure the valve swing in the sleeve (pic. 6.47).
48. If the measured result exceeds the data prescribed specifications, guide sleeve and valve are replaced together.
Note: The guide sleeves are pressed into the head and require a hydraulic press to remove them. This work is best entrusted to specialists in a suitably equipped workshop.
49. Measure the length of each spring with a caliper. Since the length of the springs specifications is not prescribed, the only way left is to compare the length of the old spring with the length of the new one. Note that valve springs are usually replaced during overhauls (pic. 6.49).
50. Check the squareness of the spring by setting it on a plane next to the corner (pic. 6.50). Replace curved springs.
Assembly
51. To obtain tightness in a valve / seat pair, it is necessary to grind the valves. This requires coarse and fine lapping pastes and a valve lapping tool - this can be either a collet tool or a suction cup tool. The drive can be either manual or mechanical.
52. Apply a little thin paste to the working bevel of the valve disc. Install the valve in your sleeve. Attach tool and twist "back and forth" lap the valve against your seat. Periodically raise the valve and rearrange, in the seat, so that the paste is distributed evenly (pic. 6.52).
53. Continue lapping until a uniform dull strip appears not only on the valve, but also on the seat. Repeat the operation with the remaining valves.
54. If the valves and seats are so burned that they require coarse paste for grinding, remember to allow the valve stem heel to protrude above the guide sleeve - do not wipe the valve seat into dust. The required heights are given in Specifications at the beginning of the chapter. If the allowable dimensions are exceeded, the hydraulic pushers will not be able to work satisfactorily.
55. Having taken into account the above information, grind the valves first with a coarse paste. Rinse off the traces of the coarse paste and then rub in the fine paste until a smooth, slightly matt working surface of the bevel is achieved.
56. Once all valves have been lapped, remove all traces of lapping paste from the cylinder head and valves with solvent and dry thoroughly.
57. On diesel heads, first install the lower spring seat with a curved plane to the head (pic. 6.57).
58. Working with each valve in turn, lubricate the valve stems with clean engine oil and insert them into the guide bushings. Slide one of the protective plastic boots included in the valve stem seal kit over the valve stem to protect the valve stem during installation (pic. 6.58, a, b).
59. Immerse a new valve stem seal in clean engine oil, place it over the valve stem and push the guide bushing through. Using a head or a special mandrel, press the cap onto the sleeve (pic. 6.59). Remove the protective cover.
60. Put on the valve (nye) spring on valve stem (pic. 6.60). On diesel engines, check that the springs are correctly installed in the lower seat.
61. Install the top seats on the spring. Using a spring compressor, compress them to install the cotters, lock them into the grooves on the valve stems. Lubricate with a drop of grease to facilitate fixing the crackers (pic. 6.61). Slowly release the compressor, make sure the crackers are set correctly. If the crackers are installed correctly, they should close.
62. Repeat the process for the rest of the valves. To securely fix the crackers after setting them, lightly tap the legs of the valve stems with a hammer through a soft metal spacer so as not to damage the valves. Before setting the pushers, once again make sure that the crackers are fixed.
63. Lubricate the outside of the tappets with clean engine oil and install them in place. Push them in, twist slightly until they stop into the valves, then lubricate the surfaces in contact with the cams (pic. 6.63).
Engines ADR, AFY, AEB, AJL
54. Lay the rubber/metal gasket on the automatic phase adjuster along with the semi-circular seal (pic. 6.64, a, b) in front of the cylinder head. If no sealant is applied to the gasket, apply a small amount of suitable sealant to the indicated area (pic. 6.64).
55. Lubricate camshafts and bearings with clean engine oil.
66. Hook the chain onto the camshaft sprockets so that there are 16 rollers between the sprocket marks (pic. 6.66).Set the adjuster between the target arms and carefully lower the camshafts into place in the cylinder head, supporting the camshafts by the ends so as not to damage the journals and cams. Alternatively, you can place the camshafts with the chain in the cylinder head, then slightly lift the camshafts by the sprockets to install the regulator.
67. Camshaft seals can be installed already at this stage or later. Immerse new oil seals in clean engine oil and slide them over the front ends of the shafts. The seals are installed with closed surfaces facing outwards. Be careful not to damage the seal lips. Install the seals in their seats.
68. Install the regulator bolts and tighten them to the specified torque.
69. Lubricate the upper surfaces of the bearing journals and install covers #2 and #4 on both camshafts. Make sure that the covers are installed correctly and tighten their fastening bolts to the prescribed torque.
Application: The covers are numbered from the back of the engine guard.
70. Install covers No. 1 on both camshafts and gradually tighten the mounting bolts to the prescribed torque.
71. Remove the locking tool from the auto adjuster.
72. Apply a thin layer of sealant to the mating surface of the front combination cover and install it so that the oil seals are not warped (pic. 6.72). Gradually tighten the cover bolts to the specified torque.
73. Install caps #5 and progressively tighten bolts to specified torque.
74. Install the Hall sensor plate on the front end of the intake camshaft and tighten the bolt to the specified torque.
75. Install the Hall sensor and tighten the mounting bolt.
ADP engines. AHL, 1Z, AFF, AFN, ANN, AHU
76. Lubricate the camshaft and bearing surfaces in the cylinder head with clean engine oil (pic. 6.76).
77. Gently lower the camshaft into the cylinder head with the cams of the first cylinder up. When installing, hold the camshaft by the ends parallel to the head so as not to damage the bearing surfaces (pic. 6.77).
78. Dip a new oil seal in clean engine oil, install it on the front end of the camshaft with the closed surface out. Be careful not to damage the seal lips. Install the seal in the seat.
79. Support covers are numbered and have a docking ledge on one side. If the covers are installed correctly, the numbers on the covers should be readable from the exhaust side of the cylinder head and the tabs should be from the intake side of the cylinder head. Lubricate the upper surfaces of the camshaft bearing journals, then install the No. 2 and No. 4 caps. Make sure they are properly installed and gradually tighten the mounting bolts to the prescribed torque (pic. 6.79, a, b).
80. Lubricate the mating surfaces of cover No. 1 with sealant and install covers No. 1, 3 and 5 on the camshaft, gradually tightening their fastening nuts to the prescribed torque (pic. 6.80).
All engines
81. If provided, install temperature and emergency oil pressure sensors in the cylinder head.
82. If provided, install the cooling system outlet flange with a new gasket/O-ring (pic. 6.82).
83. On diesel engines, install injectors and glow plugs as described in chapters 4B and 5V.
84. Install the cylinder head as described in part A or B of this chapter. Install the camshaft sprocket as described in part A or B of this chapter.
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