Emission control systems

EMISSION CONTROL SYSTEMS

The vehicle is fitted with various items of emission and evaporative control components to comply with emission regulation requirements.

Three control systems are used to reduce harmful emissions released into the atmosphere from the vehicle at all times, and under all conditions. These are:

1. Crankcase emission control
2. Exhaust emission control
3. Fuel vapour evaporative loss control

In many countries it is against the law for a vehicle owner or an unauthorised repair shop to modify or tamper with emission control equipment. In this event the vehicle owner and/or the repairer may be liable for prosecution.

The emission control system fitted to the vehicle is designed to keep the emissions within the legal limits provided that the engine is correctly maintained and is in good mechanical condition.

Crankcase emission control system - ’K’ & ’T’ series

Gases from the crankcase are drawn into throttle housing to be burnt in the combustion chambers with the fuel mixture. The system provides effective emission control while the engine is running under all circumstances.

’K’ Series

Clean air is drawn into the crankcase through a pipe connected to the air cleaner side of the throttle housing. Crankcase gases and clean air are then drawn via a pipe, through a filter in the camshaft cover, into the manifold side of the throttle housing and consumed in the combustion chambers. This pipe incorporates a restrictor to prevent engine oil being drawn into the inlet manifold by the substantially greater manifold depression.

’T’ Series

There are two breather pipes connected to the throttle housing; one either side of the throttle disc. When the engine is running with the throttle disc open, both pipes are subject to manifold depression and draw crankcase fumes into the manifold. When the throttle disc is closed, only the pipe on the inlet manifold side of the disc is subject to manifold depression. This pipe incorporates a restrictor to prevent engine oil being drawn into the engine by the substantially greater manifold depression.

Crankcase emission control system - ’D’ series

Gases from the crankcase are drawn into the inlet manifold to be burnt in the combustion chambers with the fuel mixture. The system provides effective emission control while the engine is running under all circumstances.

Clean air is drawn into the crankcase via a pipe connected to the air intake hose and camshaft cover. Crankcase gases are drawn from the crankcase via a separator and Positive Crankcase Ventilation (PCV) valve into the inlet manifold. The PCV valve contains a spring loaded plunger. When the engine is running, the plunger in the PCV valve lifts in proportion to inlet manifold vacuum and crankcase gases are drawn via a hose into the inlet manifold to be consumed in the combustion chambers.