Checking the wastegate

Warning

Be careful if the car is warm. The coolant is hot and there is a risk of burns from the intake manifold.

If the basic charging pressure cannot be adjusted then check the wastegate as follows:

Undo the hose clip on the turbocharger pressure pipe and bend the bypass pipe aside.

Remove the exhaust manifold heat shield. The heat shield is attached with a nut and two clips on the underside.

Undo the three nuts securing the front exhaust system to the turbo unit.

Important
The flexible bellows on the front of the exhaust system must not be bent more than 7 from its neutral line, which means that it must not be bent more than by its own weight when the front exhaust system is left hanging.
If the load on the pipe is too excessive the components will be permanently deformed. This can cause noise, leaks and, eventually, breakage.

Remove the locking ring and unhook the pushrod from the valve control arm, use special tool 83 94 538.

Observe whether the flap valve abuts firmly against the turbine housing. Check for carbon deposits, etc.

Check that the arm moves easily.

Refit the circlip and hook on the pushrod.

Fit the front exhaust system to the turbo. Lubricate the studs with Molykote 1000 (part no. 30 20 271).

Tightening torque: 25 Nm (18.4 lbf ft)

Important
When fitting the front exhaust system to the turbo, the nuts should be tightened alternately to avoid distorting the flange. The flange must not abut against the turbo connection flange.

Fit the heat shield.

10.

Mount the charge air bypass valve with pipe. Fit a new O-ring, lubricated with non-acidic vaseline.

Tightening torque: 8 Nm (5.9 lbf ft)