A: To ensure efficient operation of the PCV system, clean hoses and check the PCV valve as stated in the service schedule. Determine where the PCV valve is located in gasoline engines by checking for a valve cover. Start the engine, disconnecting the hose from the cover and doing vacuum test. If you feel a vacuum, it means that your system is functioning properly. If not, check for vacuum in the hose. Replace the valve if there is only a vacuum in the hose and not at its head end or inlet. It should be changed if there is no vacuum in the hose at all. Reviewing for blocked or broken hoses should be carried out where no suction exists along with inside drain tube assembly. Examine grommet for damage replacing it if necessary. Using solvent to cleanse the pipe, uncover damage while assessing it for wear and tear before installing another one.