Pic. 20.1, a. On all engines, a fresh air inlet hose connects the intake air line to a duct on the cylinder head cover, through which fresh air is drawn into the crankcase (this is a V6 model, but 4-cylinder models use a similar hose)
Pic. 20.1, b. On four-cylinder engines, the PCV valve is located on the rear right corner of the cylinder head cover and the crankcase ventilation hose (PCV hose) connects the PCV valve to the intake manifold on the back of the engine
Pic. 20.1, c. On V6 engines, the PCV valve is located on the rear right corner of the rear cylinder head cover and the crankcase ventilation hose (PCV hose) connects the PCV valve to the fitting on the underside of the manifold (In this picture, the manifold is disconnected and lifted up so that you can see where it connects to the manifold)
2. When the engine is running at idle and with a partial throttle opening, the vacuum in the intake manifold is high. Blow-by gases and vapors exit the crankcase through the PCV valve and crankcase ventilation hose (also known as PCV hose) into the intake manifold. High vacuum in the intake manifold also causes fresh air from the intake duct or air filter housing to be drawn through the fresh air intake hose into the crankcase.
3. There are no scheduled service intervals for the PCV valve or PCV system hoses. But over time, the PCV system can become less efficient as the amount of oil sludge builds up inside the PCV valve and hoses. One of the signs of a blocked system is leakage through the seals. When the blow-by gases cannot escape, the pressure in the lower zone increases, and eventually this leads to leakage through the crankshaft seals. Therefore, every time you change the oil filter, air filter, fuel filter, spark plugs, etc. it is recommended to disconnect the PCV hoses and inspect them. If the hoses are clogged, remove and clean them. If they are cracked, torn or otherwise damaged, replace them.
4. Checking and replacing the PCV valve is covered in chapter 1.