Fig. 20.1, a. On all engines, a fresh air intake hose connects the air intake manifold to a branch pipe on the cylinder head cover through which fresh air is drawn into the engine crankcase (this is a V6 model, but the 4 cylinder models use a similar hose)
Figure 20.1, b. On four-cylinder engines, the PCV valve is located on the right rear corner of the cylinder head cover, and the crankcase ventilation system hose (PCV hose) connects the PCV valve to the intake manifold on the rear side of the engine
Figure 20.1, B. On V6 engines, the PCV valve is located at the right rear corner of the rear cylinder head cover, and the crankcase ventilation system hose (PCV hose) connects the PCV valve to a branch pipe on the underside of the manifold (In this picture the manifold is disconnected and lifted up so that the connection to the manifold can be seen)
2. When the engine is idling and partially throttled, the vacuum in the intake manifold is high. Crankcase gases and vapors exit the engine crankcase through the PCV valve and the crankcase ventilation hose (also known as PCV hose) into the intake manifold. The strong vacuum in the intake manifold also causes fresh air to be drawn from the intake air duct or air cleaner housing through the fresh air intake hose into the engine crankcase.
3. There are no scheduled service intervals for the PCV valve or PCV hoses. However, over time, the PCV system can become less effective as the amount of oil sludge inside the valve and PCV hoses increases. One sign of a clogged system is leaking seals. When blow-by gases cannot escape, the pressure in the lower area increases, eventually causing the crankshaft seals to leak. Therefore, it is recommended that you disconnect the PCV hoses and inspect them whenever you change the oil filter, air filter, fuel filter, spark plugs, etc. 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.