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Checking air recirculation valve for turbocharger N249 > < Effects of leaks

A4 Mk1

Checking mechanical air recirculation valve
Checking mechanical air recirculation valve
  Note
t  The mechanical air recirculation valve is located upstream of the turbocharger. It is opened by vacuum from the air recirculation valve for turbocharger -N249- when the engine is on overrun or under part load or when idling. This dissipates the charge pressure upstream of the throttle valve and maintains a higher turbocharger speed.
t  Check air recirculation valve in the event of loss of power or load change jolts.
Special tools and workshop equipment required
   
t  Hand-operated vacuum pump -VAS 6213-
  W00-10259
Procedure
–  Connect hand-operated vacuum pump to air recirculation valve.
–  Operate hand-operated vacuum pump to produce a vacuum
l  Air recirculation valve should open -arrow-
–  Operate vent valve on hand-operated vacuum pump after approx. 30 seconds.
l  Air recirculation valve should close -arrow-.
–  Renew the air recirculation valve if it does not open and close as specified, or if the valve plate does not seal properly when the valve is closed.
  Note
Secure all hose connections with the correct type of hose clips (same as original equipment) → Parts catalogue.
  V21-0074

Checking air recirculation valve for turbocharger N249 > < Effects of leaks