GMC 19303069 PCV Valve

A PCV (Positive Crankcase Ventilation) system helps to reduce hydrocarbon emissions by passing fresh air through the crankcase, which picks up blow-by gases and then pulls them via the PCV valve into the throttle body or intake manifold where they are burned by the engine. The PCV system comprises of two hoses and a PCV valve that controls the flow of gases in relation to engine speed and manifold vacuum. On some newer models, an upper intake manifold is located over a "dirty air" tube that carries blow-by gases from the crankcase, through the PCV valve and into the throttle body. One hose brings in cool ambient air from outside through an air intake duct while another takes crankcase gases out of crankcase, through the PCV valve and into a throttle body. The PCSV system can be inspected for proper operation easily. Keep checking your PCV system, as carbon black and gunk deposited by blow-by gases will eventually clog up the "dirty" side system hose and inside of throttle body behind throttle plate as well as its valve. Common symptoms for a blocked or stuck PCV (positive crankcase ventilation) valve include rough idle, stalling or slow idle speed, oil leaks, oil in air cleaner or sludge in engine. Valves for Positive Crank Case Ventilation.