Checking the crankcase breather

When the engine is running, overpressure in the cylinders forces small amounts of gases past the piston rings into the crankcase. Oil vapours also form in the crankcase. These gases are fed back to the engine for combustion through the intake air system.

1.4 L engine: the gases exit through connection - 1 - and flow through a screen - 5 -, which prevents a flashback from the throttle body. When the throttle valve is open, the gases are drawn in through connection - 3 -.

When the throttle valve is closed, the gases are fed to the engine at idle in precisely metered quantities through hose - 2 - and a calibrated bore - 4 -.

1.6 L engine: 1 - flame trap, 2 - part-load hose, 3 - idle hose, 4 - intake hose, 5 - calibrated bore, 6 - throttle body.

Note: the other engines have a system similar to the one shown.

As part of regular maintenance, visually check the hoses for leaks.

• Check the hoses for porosity by bending them. Check that the hoses are correctly seated on their connection stubs by pulling on the hoses.

  Replace porous hoses.