Crankcase Emission Control System

Crankcase Emission Control System
The concentration of hydrocarbons in the crankcase of an engine is much greater than that in the vehicle's exhaust system. In order to prevent the emission of these hydrocarbons into the atmosphere, crankcase emission control systems are employed and are a standard legal requirement.

The crankcase ventilation system is an integral pant of the air supply to the engine combustion chambers and it is often overlooked when diagnosing problems associated with engine performance. A blocked ventilation pipe or filter or excessive air leak into the inlet system through a damaged pipe or a leaking gasket can affect the air:fuel mixture, performance and efficiency of the engine. Periodically check the ventilation hoses are not cracked and that they are securely fitted to form airtight connections at their relevant ports.

The purpose of the crankcase ventilation system is to ensure that any noxious gas generated in the engine crankcase is rendered harmless by complete burning of the fuel in the combustion chamber. Burning the crankcase vapours in a controlled manner decreases the HC pollutants that could be emitted and helps to prevent the development of sludge in the engine oil as well as increasing fuel economy.

A spiral oil separator is located in the stub pipe to the ventilation hose on the right hand cylinder head rocker cover, where oil is separated and returned to the cylinder head. The rubber ventilation hose from the right hand rocker cover is routed to a port on the right hand side of the inlet manifold plenum chamber where the returned gases mix with the fresh inlet air passing through the throttle butterfly valve. The stub pipe on the left hand rocker cover does not contain an oil separator, and the ventilation hose is routed to the throttle body housing at the air inlet side of the butterfly valve. The ventilation hoses are attached to the stub pipe by metal band clamps.