Mechanical Air Recirculation Valve, Checking

Mechanical Air Recirculation Valve, Checking

NOTE:
- The mechanical air recirculation valve is located upstream of turbocharger. It is opened by vacuum via the Recirculating valve for turbocharger N249 when the 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 the mechanical air recirculation valve if the engine is not producing full power or if it jerks when the throttle is opened and closed.

Special tools, testers and auxiliary items required







- Vacuum hand pump VAG1390

Work sequence







- Connect vacuum pump VAG1390 to air recirculation valve.
- Operate vacuum hand pump.
- Air recirculation valve should open - arrow -.
- Operate air vent valve on vacuum pump after approx. 30 seconds.
- Air recirculation valve should close - arrow - .

If the mechanical air recirculation valve does not open and close as specified, or if the valve plate does not seal properly when the valve is closed:
- Replace mechanical air recirculation valve and secure hose connections with hose clamps.