Mechanical Air Recirculation Valve, Checking

Mechanical air recirculation valve, checking

Notes:
^ The mechanical air recirculation valve is located upstream of turbocharger. It is opened by vacuum via the recirculation valve for turbocharger-N249- when engine is on overrun, idling and partial load. This reduces charge air pressure upstream of throttle valve, thereby keeping turbocharger rotating at higher speed.
^ Check air recirculation valve if engine is not producing full power, or jerks when throttle is opened and closed.

Special tools and equipment





^ Vacuum hand pump VAG 1390





Test sequence
^ Connect vacuum pump VAG 1390 to air recirculation valve.
^ Operate vacuum hand pump.
^ Air recirculation valve should open -arrow
^ Operate air vent valve on vacuum pump after approximately 30 seconds.
^ Air recirculation valve should close -arrow
^ If air recirculation valve does not open and close as specified, or if valve plate does not seal properly when valve is closed:
^ Replace air recirculation valve and secure hose connections with hose clamps.