After the valve and seat grinding, check the seal methods are:

     ① air checks issued: the pressure applied to 490kPa, the pressure should not be lower 10s;

     ② crossed method: valve work surface, each about 10mm with a soft pencil to draw a line, and then match the seat reciprocating rotary valve 1/4 turn, draw the line as to seal off are good .

     ③ oil coating method: In the valve work surface, coated with red lead oil, the pressure in the valve seat to match the rotation a little, look at the prints valve seat, if there was no interruption for good sealing.

     ④ pouring kerosene law: the valve and valve springs installed in the intake and exhaust hang doused with kerosene and kerosene shall be observed within 3min after valve leakage is qualified.