Mercury 3S4Z-6A666-MB Valve Assembly

The crankcase emission control system, also known as positive crankcase ventilation (PCV), consists of hoses connecting the crankcase to the air cleaner or intake manifold. Some engines have oil separator units located at the left-hand end or front of the engine. The system requires regular checking for blockages and damage to the hoses, valve, and oil separator. To remove the PCV valve, trace the ventilation hose to the valve and disconnect it. The valve can then be pulled out. If the hose is damaged, the thermostat housing may need to be removed for access. Wash the valve in a suitable solvent and ensure all passages are clear. Check the hoses for damage, especially at the ends, and inspect the condition of the O-ring if present. Installation is the reverse of removal, ensuring secure and correct hose installation. The oil separator is located behind the exhaust manifold and catalytic converter on the front of the engine block. Access requires removing the manifold and converter. Disconnect the hose or remove the PCV valve. The separator is secured by three bolts, which should be unscrewed to remove the separator and recover the gasket. If not already done, remove the PCV valve from the separator and wash the separator with a suitable solvent. Ensure clear passages and use a new gasket when reinstalling the separator, tightening the bolts securely.