Steps to replace the valve seat

The maintenance of the valve seat is very important. Here are some simple steps to replace the valve seat:

Use a reamer to thin the valve seat or spot weld several solder joints on the inner side of the valve seat, tap the solder joints, and remove the valve seat.

• Measure the diameter of the seat ring hole and select a new seat ring according to the size of the diameter hole.
• In order to prevent loosening, the new seat ring and the seat hole should have an interference of 0.075-0.125mm.
• The valve seat ring material should be made of alloy materials with less plastic deformation and higher hardness at operating temperature, generally alloy cast iron, ductile iron, There are also alloy steels.
• Usually the hardness of the seat ring is slightly lower than the hardness of the valve working surface.

• The valve seat ring is usually inserted into the seat hole by cold shrinking method or heating method.
• The cold shrink method is to freeze the valve seat ring in liquid nitrogen to -195°C and then press the seat hole.
• The thermal expansion method is to heat the bearing hole of the seat ring to about 100°C, then oil the seat ring, and press the seat ring into the bearing hole quickly with soft metal.
• After the valve seat ring is inserted, the part higher than the plane of the cylinder block (cylinder head) should be smoothed.