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The first refinement in crankcase ventilation was the road draught tube. This is a pipe running from the crankcase (or the valve cover on an overhead valve engine) down to a downwards-facing open end located in the vehicle's slipstream. When the vehicle is moving, airflow across the open end of the tube creates suction (a "draught" or draft ...
During normal operation of a car engine, some vapors from the cylinder pass by the piston rings and down into the crankcase. Without ventilation this can pressurize the crankcase and cause issues such as lack of piston ring sealing and damaged oil seals. To avoid this, manufacturers created a crankcase ventilation system. Originally this was ...
The first effort at controlling pollution from automobiles was the PCV (positive crankcase ventilation) system. This draws crankcase fumes heavy in unburned hydrocarbons – a precursor to photochemical smog – into the engine's intake tract so they are burned rather than released unburned from the crankcase into the atmosphere. Positive ...
A crankcase is the housing in a piston engine that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, resulting in the fuel/air mixture passing through the crankcase before entering the cylinder(s). This design of the engine does ...
This is known as a positive crankcase ventilation system, in which the gases are burned with the fuel/air mixture. The intake manifold has historically been manufactured from aluminium or cast iron, but use of composite plastic materials is gaining popularity (e.g. most Chrysler 4-cylinders, Ford Zetec 2.0, Duratec 2.0 and 2.3, and GM's Ecotec ...
This mixture can also cause problems with components such as swirl flaps, where fitted. (These problems, which effectively take the form of an undesirable positive-feedback loop, will worsen as the engine ages. For example, as the piston rings progressively wear out, more crankcase oil will get into the exhaust stream.
The CVH is known for producing excessive sludge if the service schedule is ignored or if poor quality oil is used. The cause is the design of the crankcase ventilation circuit, which Ford revised several times over the engine's lifetime but never completely cured. Due to this, camshaft and tappet wear problems are common.
Failure to use the correct specification oil has been known to cause PCV (positive crankcase ventilation), VVT (variable valve timing) system, gasket and sealing system, and other internal combustion component premature clogging and other failures. Some of the additives in those specs are designed to aid in keeping systems lubricated and clean.