Mercury D9DZ-6A666-A Valve Assembly

You can Select Your Vehicle to check if D9DZ-6A666-A fits your vehicle.

Hydrocarbon emissions are reduced by the Positive Crankcase Ventilation (PCV) system which scavenges crankcase vapors, passes them through the air cleaner, and mixes them with blow-by gases before redirecting them back to the intake manifold through a PCV valve. The main components of the PCV system are, fresh air filtered inlet, vacuum hoses connecting these two components with the engine and EECS system, and PCV valve. The flow is restricted when there is high intake manifold vacuum so as to maintain idle quality, this is achieved by using PCV valve. When abnormal operating conditions occur, the system allows excessive amounts of blow-by gases to pass back into the air cleaner through the crankcase vent tube for normal combustion.

PCV systems universally incorporate a PCV valve mounted in the valve cover or intake manifold, connected to the main intake manifold vacuum port via a sizable vacuum hose.

The PCV valve can be checked by pulling it out of the rocker arm cover and shaking it. If it rattles, it can be reinstalled. If it doesn't rattle, it's likely clogged with deposits and should be replaced.

The hose between the valve and the intake manifold should be removed and cleaned with solvent. After cleaning, the hose should be inspected for damage, wear, and deterioration. If necessary, a new PCV valve should be installed.

The PCV valve restricts the flow when the intake manifold vacuum is high, which helps maintain idle quality.

During abnormal operating conditions, excessive amounts of blow-by gases are allowed to flow back through the crankcase vent tube into the air cleaner to be consumed by normal combustion.

The PCV valve is located in the valve cover.

Clean the hoses and check the PCV valve at the intervals recommended in the maintenance schedule.

Install the clean PCV system hose and ensure that the PCV valve and hose are secure.