Disassembly
1. Remove the cylinder head.
2. Unscrew and remove the intake and exhaust manifolds.
3. Remove camshafts and hydraulic tappets.
4. Compress the valve springs in order with a special tool and remove the crackers securing the upper thrust plate of the spring.
5. Remove the top plate.
6. Remove the upper and lower valve springs, being careful not to damage the valve stem
7. Remove the valve from the cylinder head from the combustion chamber side.
8. Remove the oil seals.
9. Remove the lower valve spring cap.
10. Locate the valve kits in plastic bags and label them for installation.
Cleaning and checking
1. Clean the traces of the old gasket and sealant from the cylinder head.
2. Clean carbon deposits from the combustion chamber and cylinders, then wash the cylinder head with an appropriate solvent.
3. Clean the channels in the cylinder head with a wire brush.
4. Carefully inspect the head for cracks or other damage. If there are cracks in the head, the head must be replaced.
5. Using a metal ruler and feeler gauge, check the flatness of the head mating surface.
6. Valve seats with signs of wear or burning must be processed with the obligatory preservation of angles and chamfers. If the valve seat needs to be machined, determine the maximum amount of metal that can be removed. If excessive metal is removed, hydraulic tappets will not work properly.
7. Insert the valve into the guide and press it against the valve seat.
8. Measure the distance from the end of the valve stem to the top surface of the cylinder head. The minimum allowable distance is 33.8 mm for intake valves and 34.1 mm for exhaust valves. If the valve seat is excessively worn, machining is unacceptable and the cylinder head must be replaced.
9. After any treatment of valve seats, they must be lapped.
10. Check the inside diameters of the valve guides. If the values exceed the maximum allowable value, the valve guides must be replaced by a specialist workshop.
Warning: Replacing a guide also requires regrinding the corresponding valve seat.
11. Check each valve seat for pitting, burns, cracks, and general wear.
12. If the condition of the valve is satisfactory, then measure the diameter of the valve stem at several points using a micrometer. Any significant difference in valve stem measurements obtained indicates stem wear. In this case, the valve must be replaced.
13. If the valves are in a satisfactory condition, then it is necessary to grind them. The valves should only be lapped with a fine-grained polishing paste. Lubricate the surface of the valve seat with a small amount of paste and install the valve in the appropriate seat. Firmly press the rubber suction cup against the valve disc and rotate the valve to one side or the other.
14. After the end of the lapping process, thoroughly clean all parts from dirt and paste. Check valve seat and poppet. A solid opaque ring should be visible on both parts, which indicates the width of the valve chamfer.
15. Check the valve springs for wear and tear, and measure their free length. If possible, compare each of the existing springs with the new spring.
16. Install the springs on a flat horizontal surface and check for deviations from the horizontal position. If at least one of the springs is damaged, then completely replace all the springs in the kit.
17. Check the condition of the valve cotters, as well as the location of the cotters on the valve. If there are any defects, damaged parts must be replaced. The oil seals must be replaced each time they are removed.
18. Check valve train parts and hydraulic tappets.
Assembly
1. Before assembling the cylinder head, clean it thoroughly.
2. Lubricate the valve stems and guides with clean engine oil and insert the valves into the head.
3. Install the lower valve spring cap.
4. Wipe the top of the valve stem free of engine oil.
5. Install a plastic sleeve or wrap the cracker grooves in the top of the valve with a piece of adhesive tape to protect the sealing edges of the valve stem seals from damage when they are installed.
6. Lubricate the valve stem seal with fresh engine oil and, using a pipe mandrel, install on the valve guide.
7. Remove adhesive tape from valve stem.
8. Press the oil seal into place.
9. Install the springs and upper spring plate.
10. While maintaining the valve in the closed position, compress the valve spring with a special tool and install the crackers. Slowly remove the valve spring compressor.
Repeat the operation on the remaining valves.
11. Finally, hit the end of each valve stem with a plastic or copper mallet to open the valve slightly and place all of the valve parts in place.
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