1. Having removed the cylinder head as previously described, the valves can be removed as follows. The valves are deeply inserted into the top of the cylinder head and therefore require a valve spring puller with long claws to remove them. One method is to use a tube about the same diameter as the valve spring cover and long enough. To remove the valve locks, cut a groove in the pipe on each side so that three-quarters of a circle remains.
2. Prepare a pallet with holes according to the number of valves and appropriately marked so that each valve and associated parts can be stored separately as it is removed. Inlet valves - No. 2-4-5-7, exhaust valves - No. 1-3-6-8, numbered from the drive timing belt.
3. Compress each valve spring until the valve locks are removed (photo). Remove the valve locks, release and remove the spring extractor.
4. Remove valve spring cover, inner and outer springs and valve (photo). It is good practice to store the valve springs so that they are oriented the way they were before removal when installing.
5. Remove and discard valve stem seals, then remove valve spring seat (photo).
6. Check the condition of the valve heads for pitting and burnt spots, pay special attention to the exhaust valve heads (photo). Also check the valve seats. If there is slight pitting on the valve and seat, it can be removed by sanding the seat and infusion valve. Otherwise it will be necessary to replace the valve and grind off the valve seat. Do not grind the valve head.
7. If the valve seat is worn off, it is important to determine the maximum amount of metal that can be removed from the seat. If more than this is removed, the hydraulic tappets will not function properly. Insert the valve into the guide and press firmly against the seat. Now measure the distance from the end of the valve stem to the top surface of the cylinder head (pic. 1.4). The minimum allowable distance is 33.80 mm for intake valves and 34.10 mm for exhaust valves. Now, before grinding the seat, it is possible to calculate the maximum amount of metal to be removed. If the valve seat is excessively worn and grinding is not possible, the cylinder head must be replaced.
8. Lapping of valves is performed as follows. Apply a small amount of lapping paste around the contact surface of the valve or seat, insert the valve into the guide. Place a vacuum lapping tool on the valve head and grind the valve with a semi-rotary motion. When resistance is felt, remove the valve, rotate and repeat until a uniform matt gray surface is obtained over the entire head and valve seat bearing surface area.
9. Clean all carbon from the valve head and valve stem. Carefully remove any remaining paste, being careful not to leave any in the channels or guide bushings. Wipe the valves and seats with a kerosene-soaked rag and then with a clean, dry rag.
10. Completely clean the cylinder head, then check its distortion by placing the edge of the ruler in several places, in the longitudinal, transverse and diagonal directions and measuring the gap under it with feeler gauges (photo). If the clearance exceeds the limit given in the Specifications, consult an Audi dealer before replacing the head. When regrinding, the height of the cylinder head must not be less than the minimum value given in the Specifications.
11. Examine the cylinder head for cracks. If there are small cracks between the valve seats or at the bottom of the spark plug holes, no more than 0.5 mm wide, the head can be reused, but the cylinder head cannot be restored or new valve seat inserts installed.
12. Check the condition of the valve guides. Clean the guide first, then insert the new valve stem into the guide. Due to the different diameter of the valve stems, check that only the intake valve is used to check the intake valve guides, and the exhaust valve is used for the exhaust valve guides. With the end of the valve stem level with the top of the valve guide, measure the total lateral movement of the valve head rim. If the offset exceeds the maximum value given in the Specifications, it is necessary to install new guides, but this is a job for the Audi dealer or a specialist, as this requires special equipment.
13. To install the valves, lubricate the valve stem and insert the valve into the guide.
14. Position the valve spring seat on the guide.
15. Position the special plastic sleeve on the end of the valve stem, then lower the new valve stem seal into the oil and slide it over the valve stem onto the guide. If the plastic sleeve is not available, wrap thin tape around the top of the valve stem so that it covers the notch for the valve locks. This will prevent damage to the valve stem seal. Remove the sleeve or band after installing the cap. To install the cap on the guide, you can use the socket and a light mallet (photo).
16. Install the inner and outer valve springs, then the valve spring cover. The springs on any valve should only be replaced in pairs.
17. Install the puller and compress the spring just enough to install the valve locks. If the spring is pressed more than necessary, there is a risk of damage to the valve stem seal.
18. Install the valve locks, slightly release the spring remover and check that the valve locks are properly positioned, then remove the compressor.
19. Hit the top of the valve stem with a hammer to check that the valve locks are properly seated.
20. Repeat the procedure for all valves.
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