Mechanical Air Recirculation Valve, Checking

Mechanical air recirculation valve, checking

Note:
^ The mechanical air recirculation valve is upstream of the exhaust turbocharger. It is opened via vacuum by the recirculating valve for turbocharger -N249- under conditions of overrun, idling and partial load. This reduces the charge pressure upstream of the throttle valve. A high turbocharger speed is thus maintained.
^ Check the air recirculation valve if the engine is not producing full power, or jerking when the throttle is opened and closed.

Special tools and equipment





^ Hand vacuum pump V.A.G 1390





Test sequence
^ Attach vacuum pump V.A.G 1390 to air recirculation valve.
^ Actuate hand vacuum pump.
- Air recirculation valve should open - arrow-

^ Operate air vent valve on vacuum pump after about 30 seconds.
- Air recirculation valve should close - arrow-

If the 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 air recirculation valve and attach hose connections with hose clamps.