In a garage environment, you can disassemble, flush, inspect, reassemble the cylinder head and take it to the dealer's car service center or to specialized valve repair shops.
In the service center or specialized workshops, the following types of work are performed: removing springs and valves, grinding or replacing valves and guide bushings, checking and replacing springs, circlips and crackers (as needed), replacement of valve stem seals, replacement of valve parts, checking the height of the spring in a free state. If the deviation from flatness exceeds the norm, the cylinder head must be ground.
After the inspection and repair of the valves and their parts by experienced personnel, the cylinder head is completely restored. Before installing the cylinder head, flush it again to remove abrasive residue from grinding the head or lapping the valves. If possible, blow out all channels and openings with compressed air.
Valve grinding
If the chamfers of the valves and seats have slight wear or new valves are installed on non-worn seats, then the valves must be lapped to the seats. The lapping operation is performed as follows.
Apply a small amount of coarse abrasive paste to the face of the seat. Insert the valve into the guide sleeve and, turning and pressing the valve, lap it against the seat. To perform this work, you will need a device in the form of a tube with a piece of rubber hose inserted inside. Lapping can also be done with an electric drill by inserting this device into the chuck. While lapping, periodically raise the valve to check the result and redistribute the lapping material.
When a smooth, continuous band forms on the valve head or seat bevel, remove any remaining coarse abrasive paste and continue lapping with fine paste.
After lapping all valves to the seats, thoroughly wash the lapped areas with kerosene to remove abrasive residues, wipe with a rag and, if possible, blow with compressed air. Abrasive residues in the cylinder head can cause increased wear on parts.
It should be noted that with excessive grinding of old valves, the location of the belt may be disturbed and become unacceptable. If new valves are lapped onto old seats, excessive lapping can lead to «pockets».