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Crankcase Ventilation Systems - Domestic: Maintenance: Notes

NOTE: An engine may idle slow or rough due to clogged ventilator valve or system; therefore never adjust carburetor idle without first checking valve and system.
If the ventilator valve or system becomes clogged, all crankcase ventilation will stop and serious engine damage could result.
Although the following manufacturers' service procedures give specific intervals, it is recommended the crankcase ventilation system be checked more frequently if vehicles are operated under severe conditions (extreme dust, prolonged idling, trailer hauling or short trips in cold weather).