Crankcase ventilation system
The function of the crankcase ventilation system is to reduce the emission of unburned hydrocarbons in the gases escaping into the crankcase, and to minimize the formation of oil sludge.
On HCS engines, the system consists of a vented oil fill head (with compound filter) and a hose connecting the engine breather valve to the back of the air filter housing.
On CVH engines, a closed crankcase ventilation system is used, the function of which is basically the same as for HCS engines, but the ventilation hose is connected directly to the cylinder head cover. A separate filter is installed in the hose to the head cover.
The systems installed on the Endura-E and PTE engines are similar to those used on the HES and CVH engines, but with a different hose layout to connect the remote air filter and fuel injection system.
On Zetec and Zetec-E engines, the main components of the crankcase ventilation system are the oil separator mounted on the front side of the cylinder block and the Positive Crankcase Ventilation (PCV), that is, a set of valves located at the upper left end of the separator.
The connection consists of a crankcase ventilation tube and two flexible hoses connecting the PCV valve to the fitting on the left front end of the intake manifold, and a crankcase ventilation hose connecting the cylinder head cover to the air filter housing.
On HCS engines, remove and inspect the oil filler cap to make sure it is in good condition and not contaminated.
With the air filter element removed, wipe down the housing, and on Zetec engines, remove the small filter from its slot in the rear right corner of the housing. If the filter is contaminated with thickened oil, it must be cleaned in an appropriate solvent, dried and reinstalled (see fig. 1.30).
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