The reason for abnormal noise in the hoist is mostly due to air entering the hydraulic system. If there is no abnormal noise at the beginning of use and noise appears after three months of use, check the level of hydraulic oil in the hydraulic oil tank. If it is above the minimum required level, add the same specification of hydraulic oil to the top of the tank. Otherwise, contact your nearest service provider to troubleshoot the problem. If there is abnormal noise from the beginning of use, check the installation of the suction pipe for compliance with the installation requirements in the diagram below.