Answer: (1) Cause analysis.
1) The intake valve is not closed tightly or is stuck;
2) The check valve is leaking;
3) The heavy vehicle is shut down;
4) The oil fine separator is damaged;
5) The pressure maintenance valve is leaking;
6) The discharge valve is not discharging.
(2) Elimination method.
1) Repair the intake valve and replace it if necessary;
2) After disassembly, check whether the valve plate and valve seat are worn, and replace them if worn;
3) Check whether the intake valve is stuck, disassemble and clean it, and add lubricating grease;
4) Replace the oil fine separator;
5) Repair and replace it if necessary;
6) Check the discharge valve and replace it if necessary.
