Note: Both new and remanufactured cylinder heads are available from Audi dealers. Special tools are required to disassemble and inspect the head, and the necessary components are not always available for sale. Therefore, it is probably more practical to buy a remanufactured head than to sort it out yourself.
Disassembly
1. Remove the head from the cylinder block as described in Section 1A.
2. Remove injectors and glow plugs (see Sections 3A And 4B).
3. Where available, see Section 2 and remove the coolant outlet elbow together with the gasket/O-ring (see illustrations).
4. Where available, unscrew the coolant sensor and oil pressure sensor from the cylinder head.
5. Store related components together after removal in labeled containers to avoid confusion during installation and install each group of parts exactly in the same place (see illustration). Random installation of components will accelerate their wear. Note that cylinder #1 is located at the front end of the engine.
6. Make sure the camshaft bearing caps have the manufacturer's identification marks. If this is not the case, mark them yourself with a marking tool or punch.
7. Remove the camshaft bearing caps as described below.
8. Loosen the nuts of bearing caps #2 and #4, then bearing caps #1 and #3 (see illustration). Work in a diagonal sequence, turning the nuts half a turn at a time, remove the nuts, then remove the bearing caps. Store the covers in the order they were removed and mark the correct orientation of each.
6.8 Cylinder head components
1 - Nut
2 - Pin
3 - Bearing caps
4 - Camshaft
5 — Hydraulic pusher
6 - Valve crackers
7 — The top support of a spring of the valve
8 - Outer valve spring
9 - Internal valve spring
11 — Maslosemny cap of a valve stem
12 - valve guide
13 - Rear oil seal
14 - Nozzle
15 - Heat shield
16 - glow plug
17 - Cylinder head
18 - Valves
19 - Front oil seal
Note: The camshaft bearing caps are numbered 1 to 4 from the timing belt end.
9. Remove the oil seal from the front end of the camshaft - it must be replaced. On the 3D engine, also remove the rear camshaft oil seal.
10. Carefully lift the camshaft out of the cylinder head, keeping it in a horizontal position so as not to damage the cams and bearing journals. Remove the oil seal from the front end of the shaft.
Engine 1T
11. Unscrew the nuts of the bearing caps No. 2 and No. 4, then the bearing caps No. 1 and No. 3. Loosen the nuts in a diagonal sequence, turning them half a turn at a time, remove the nuts, then remove the bearing caps (see illustrations). Store the covers in the order they were removed, marking the orientation of each.
Note: The camshaft bearing caps are numbered 1 to 4 starting from the toothed belt end.
12. Remove the front and rear camshaft oil seals and discard them - they must be replaced.
13. Carefully lift the camshaft off the cylinder head, keeping it horizontal so as not to damage the cams and bearing journals (see illustration).
14. Remove the hydraulic tappets from the guides and store them with the valve contact face down to prevent oil spillage (see illustration). Mark the tappet of each valve, as they must be installed on the same valves during assembly. A messy installation will greatly accelerate wear.
All engines
15. Turn the cylinder head on its side. Using a special puller, compress each of the valve springs in turn and remove the crackers. If the spring seat is jammed, tap on the upper leg of the puller with a hammer (see illustration).
16. Remove the puller and remove the upper spring seat, the valve spring itself and its lower seat (see illustrations).
Note: Depending on the engine, the valves may have concentric double springs or single springs.
17. Using pliers or a special tool, remove the valve stem oil seal. Remove the valve from the cylinder head gasket side. Repeat this step for the remaining valves (see illustrations).
Cleaning
18. Using a suitable solvent, clean the oily residue from the cylinder head, paying particular attention to the camshaft bearings, hydraulic tappet holes, valve guides and oil grooves. Scrape off all traces of the old gasket from the contact surfaces, being careful not to damage the soft metal. Turn the head over and, using a blunt tool, scrape off the carbon deposits from the combustion chambers and the edges of the holes. Finally, wash the head with solvent to remove any remaining dirt.
19. Clean the valve heads and stems using a soft wire brush. If the carbon layer is too thick, first scrape off the main part of it with a blunt instrument, and then use a wire brush.
20. Thoroughly clean the rest of the components using solvent and allow them to dry. Throw away the seals - they must be replaced.
Inspection
cylinder head
Note: On diesel engines, the cylinder head and its components cannot be remanufactured (although the valves can be lapped). If the head is damaged or worn beyond the limits specified in the Specifications, replace it.
21. Carefully inspect the head for damage. Pay special attention to areas adjacent to valve seats and spark plugs. If the cracks found in this area are no wider than 0.5 mm, the manufacturers claim that the cylinder head can not be changed. Otherwise, the head must be replaced.
22. Valve seats that are not too deeply burned can be repaired by lapping the valves against them as described later in this Section. Heavily worn or damaged saddles can be re-sharpened, but this work should be left to a specialist.
23. Check up a head of the block of cylinders on deformation, using an edge of a ruler and a set of probes. Take a measurement on the contact surfaces of the intake and exhaust manifolds (longitudinally). Take several measurements across the seating surface of the head (see illustration). Compare the measurement results with the data given in the Specifications. On petrol engines, the head can be reground.
24. Measure the height of the cylinder head (head seat to valve cover gasket). The minimum height is specified in the Specifications (where defined by the manufacturer).
camshaft
25. Inspect the cams and camshaft journals for signs of wear. Their surfaces should be smooth and dull gleam. Scratches, pitting and polished areas indicate wear, which now, after the destruction of the outer reinforced layer, will occur even faster. Be sure to replace worn components.
Note: If signs of wear are found on the working surface of the cams, also inspect the corresponding pushers, they are probably also worn.
26. Where available, inspect the distributor drive gear for damage and signs of wear. Excessive chain slack caused by worn gear teeth will knock the ignition timing off.
27. If the treated surfaces of the camshaft have slightly changed color or even turned blue, the shaft has probably overheated, possibly due to a lack or poor quality of lubricant. Overheating could lead to deformation of the shaft. To check this, place the camshaft between two V-shaped bearings and use a micrometer to measure the runout of its center journal. If it exceeds the value given in the Specifications, replace the camshaft.
28. To measure the camshaft end play, temporarily install the camshaft into the cylinder head, then the outer bearing caps, and tighten the mounting nuts with Stage 1 torque (see specs). Attach a micrometer to the end of the cylinder head facing the toothed belt and align the gauge probe with the camshaft axle. Move the camshaft along the axis until it stops in one direction, then rest the micrometer probe against the end of the shaft and reset the device. Move the camshaft as far as possible in the opposite direction and record the readings of the device. Check the result by moving the shaft to its original position (see illustration).
Note: The hydraulic tappets must be removed for this measurement.
29. Compare the result with the data given in the Specifications. Excessive end play is unlikely to be caused by wear on just one of the components, so the camshaft, cylinder head, and bearing caps will most likely need to be replaced.
30. Measure the operating clearance of the camshaft bearing. One Method (micrometers or internal/external calipers required) is to measure the diameter of the journals of the camshaft bearings and the diameter of the holes formed by the bearing caps and the cylinder head. The difference between these two measurements is the operating clearance of the bearings.
31. Second (and more accurate) the method consists in using a special Plastigage tool. The tool consists of a scale and plastic threads of round cross section. Proceed as follows.
32. Make sure that the running surfaces of the bearings in the cylinder head, on the camshaft and covers are completely clean and dry. Place the camshaft in the cylinder head.
33. Place a piece of Plastigage thread on each of the camshaft bearing journals.
34. Install the bearing caps and progressively tighten the mounting nuts to the specified torque. This will flatten the Plastigage thread.
Note: Where tightening is done in multiple steps, tighten the nuts only up to the first step. Do not rotate the camshaft until the bearing caps are removed - this will distort the measurement results.
35. Unscrew the nuts and carefully remove the bearing caps so as not to press on the Plastigage thread, which should remain on the camshaft.
36. Attach the scale supplied with the tool to the neck of each bearing, and compare the width of the flattened threads with it. The operating clearance of the bearing is indicated on the scale.
37. Compare the measurement results with the data given in the Specifications; if the operating clearance of any of the bearings is out of tolerance, the camshaft and cylinder head must be replaced.
38. Finally, remove the camshaft and wash off all traces of Plastigage from it and the bearing caps.
Note: On all engines described, the valve heads cannot be reground, although they can be ground.
39. Inspect each valve for signs of wear. Check valve stems for gouges and scratches. Measure their diameter at several points with a micrometer to make sure it is the same throughout the length of the stem (see illustration).
40. Valve heads must not be cracked, severely corroded or burnt. Note that light pitting can be removed by grinding the valve.
41. Check that the end surface of the valve stem is not corroded or worn, which would indicate a faulty hydraulic tappet or incorrect valve clearance adjustment.
42. Insert each valve into the corresponding guide in the cylinder head (the end of the valve stem should be flush with the top of the guide) and rest the micrometer probe against the edge of the valve head. Move the valve horizontally and measure the maximum lateral displacement of the stem in the guide (see illustration).
43. If the measurement result exceeds the data given in the Specifications, the valve and its guide sleeve should be replaced.
Note: The valve guides are pressed into the cylinder head and require a hydraulic press to remove them.
44. Using a caliper, measure the free length of each of the valve springs. Manufacturers do not provide any data, and the only way to determine if the spring is weakened is to compare its free length with the length of a new component (see illustration).
45. Set each spring on a flat surface, and check them for deformation using a corner (see illustration). If any of the springs are damaged, deformed or weakened (its free length is less than the free length of the new spring), replace it.
Assembly
46. To achieve a tight fit of the valves to the seats, it is necessary to grind them. This will require coarse and fine-grained grinding paste and a special tool - a mechanical (rubber suction cup) or electrically driven.
47. Apply a small amount of fine grinding paste to the seat contact surface of the valve head. Turn the cylinder head upside down with the combustion chambers up and insert the valve into its corresponding guide. Attach a grinding tool to the valve head and, rotating the valve back and forth a half turn, grind its head, lapping it against the seat. Raise the valve periodically to redistribute the paste (see illustration).
48. Continue lapping until the valve/seat contact surfaces are dull grey. Repeat the procedure for the remaining valves.
49. If the valves and their seats are badly corroded, use a coarse grinding paste first. Please note that the Specifications give the maximum length of the part of the valve stem protruding from the guide bushing. If this part of the stem lengthens excessively due to grinding (valve seat is deeper), the hydraulic tappets may not work properly.
50. Proceed as above, continuing sanding until the contact surfaces are evenly dull in color. Wash off the coarse paste with solvent and repeat the procedure using a fine-grained compound.
51. When all valves are lapped, remove all traces of grinding paste from the cylinder head and valves using a solvent and allow them to dry.
52. Turn the head on the side wall. Install the lower spring seat with the convex side into the cylinder head (see illustration).
53. Lubricate the valve stem with clean engine oil and insert it into the guide. Install one of the protective plastic bushings sold with new valve stem seals on the end of the stem - it will protect the cap from damage during installation (see illustrations). Repeat for the remaining valves.
54. Dip a new valve stem seal in clean engine oil and carefully slide it over the valve into the guide sleeve. Use a suitable socket or tool to drive the cap into position (see illustrations). Remove the protective sleeve.
55. Install the valve springs (see illustration). Make sure the springs are properly seated on the lower supports.
56. Install the upper spring seats, then, using a puller, compress the springs so that the upper seat is below the cotter grooves in the valve stem. Install the valve cotters, using a drop of lubricant to hold them in the grooves (see illustrations). Gradually release the pressure of the spring remover, making sure that the cotters do not move.
57. Repeat this step for the remaining valves. To adjust the position of the components after installation, tap the stem end of each valve with a mallet, covering the stem with a block of wood to protect it from damage. Check again that the valve cotters are blocked by the upper spring seat.
58. Lubricate the side surfaces of the hydraulic tappets with clean engine oil and install the tappets in working position in the cylinder head. Push them down until they touch the valves, then lubricate the contact surfaces of the camshaft cams (see illustration).
59. Lubricate the bearing surfaces of the bearings on the camshaft and in the cylinder head with clean engine oil (see illustration).
60. Gently lower the camshaft into the cylinder head, making sure the cam faces for cylinder no. are facing up. Support the shaft ends to prevent damage to the cams and journals.
61. Dip new seals in engine oil, then install them on the front and rear ends of the camshaft. Make sure the seal is oriented with the closed face outward and do not damage the lip of the seal.
62. Lubricate the contact surfaces of the bearing cap No. 4 with sealant (see illustration).
63. Lubricate the upper surfaces of the camshaft bearing journals with oil, then install the bearing caps No. 2 and No. 4 (see illustration). Make sure that the covers are oriented correctly and each is installed in its original place, then gradually tighten the mounting bolts with the tightening torque regulated by the Specifications. To avoid misalignment of the camshaft, first install the #2 bearing cap, then press the camshaft and install the #4 bearing cap.
64. Lubricate the contact surfaces of bearing cap #1 with sealant, then install caps #1 and #3 and progressively tighten the nuts to the specified torque.
65. Where available, install a coolant temperature sensor and an oil pressure sensor in the cylinder head.
66. Where necessary, install the coolant outlet elbow with a new gasket/O-ring as described in Section 2 (see illustration).
67. Install injectors and glow plugs (see Sections 3A And 4B).
68. Install the cylinder head (see Section 1A).
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