Action
The closed crankcase ventilation system is used on all HONDA vehicles. This system returns unburned fuel (those. leaking through the piston rings) into the intake manifold for combustion along with the air/fuel mixture. The oiler cap is sealed, air is removed from the top of the crankcase to the intake manifold through a valve with a blocked hole.
This valve (PCV valve) regulates the flow of air into the collector depending on the degree of vacuum in the collector. When the throttle is wide enough open, the PCV opens to maximize flow, however at idle, when the manifold suction action is at its maximum, the PCV valve reduces flow as the need for recirculation of the mixture entering the engine is reduced. The recirculation system depends on the tightness of its connections. Air leaks anywhere in the valve cover, cylinder head gasket, oil sump, dipstick location, air intake ducts in the oiler cap, or vacuum hoses can cause the air/fuel mixture to supersaturate with air and reduce recirculation efficiency. A wrongly connected hose will cause the manifold to fill with oil, stop the engine and/or leak oil.
Testing and Troubleshooting
The PCV valve is easily checked by running the engine at normal idle (engine warm-up mode). Lightly press your finger against the open end of the valve. A whistle should be heard. If there is no whistling, remove the valve from the valve cover or separators, place a finger on the open end of the valve. You should hear a whistle and feel the vacuum.
If there is no vacuum, check the connected hoses and connections. If they are open, then the valve is faulty. With the engine off, completely remove the valve. Shake it to listen for the rattling of the plunger inside the valve. If rattling is not heard, then the plunger is jammed (probably oil soot) and the valve should be replaced. Never operate the engine without a PCV or with a clogged hose.
DO NOT attempt to blow out the valve: gasoline vapors and sediment on the valve are harmful to health.