Checking the wastegate (B235R, B205L/R)

If the basic charge pressure cannot be adjusted, check the wastegate as follows:

1. Detach and move aside the bypass pipe with valve.
   Fig 1: Detaching And Moving Bypass Pipe With Valve

   
2. Remove the exhaust manifold heat shield. The heat shield is fastened with a nut and two clips underneath.
3. Undo the nuts securing the front exhaust system to the turbocharger.
   IMPORTANT: The flexible bellows on the front part of the exhaust system must not be exerted to bending over 5° from its neutral position, i.e. if the front exhaust system is left hanging, it must not be bent more than by its own weight.

   If the pipe is strained too much there may be permanent deformation of its components. This may cause noise, leaks, and finally breakage.

   NOTE: Lubricate the nuts with engine oil, for example, and undo them carefully.
4. Remove the locking clip and unhook the pushrod from the valve operating arm.
   Fig 2: Removing Locking Clip And Unhooking Pushrod From Valve Operating Arm

   
5. Visually check the flap valve contact with the turbine housing. Be especially observant for carbonization, etc.
6. Check that the arm moves easily.
7. Hook on the pushrod and fit the locking clip.
   Fig 3: Hooking On Pushrod And Fit Locking Clip

   
8. Fit the front exhaust system to the turbocharger. Lubricate the studs with Molykote 1000, part no. 30 20 971.
   Fig 4: Fitting Front Exhaust System To Turbocharger

   

   Tightening torque: 24 Nm (17.7 lbf ft) 

   IMPORTANT: The nuts must be tightened alternately when fitting the front exhaust pipe to the turbocharger so that the flange is not deformed. The flange must not be in contact with the turbocharger connecting flange.
9. Fit the heat shield.
10. Fit the bypass valve with pipe. Fit a new O -ring coated with acid-free petroleum jelly.

    Tightening torque: 8 Nm (5.9 lbf ft)