Checking and Adjusting Basic Boost Pressure

Checking and adjusting basic boost pressure







1 Remove the bypass pipe with valve, 1 screw on the turbo intake pipe and 1 hose clip on the turbo delivery pipe.

NOTE: There is an O-ring at the bypass pipe mounting on the compressor inlet.

2 Remove the exhaust manifold heat shield. The heat shield is attached with a nut and two clips on the underside.
3 Remove the operating arm clip using tool no. 83 94 538.







4 Grip the pushrod with a pair of pliers, tool no. 83 94 066 or similar. Undo the locknut using tool no. 83 94 520 or equivalent.
5 Hold the operating arm and detach the pushrod from the operating arm. Secure the arm as there is otherwise a risk that it will "jump."
6 Move the operating arm on the boost pressure control valve to the "Closed" position and adjust the end piece so that the pushrod can easily be fitted on the operating arm pin.
7 Detach the pushrod from the operating arm pin. Turn the end piece clockwise approx. 2 turns so that a prestress of 2 mm is obtained. Attach the push rod to the operating arm pin. Fit the locking ring.
8 Detach the hose from the diaphragm unit on the compressor.







9 Connect the pressure/vacuum pump, tool no. 30 14 883, to the diaphragm unit and pressure gauge, tool no. 83 93 514.
10 Carefully pump up a pressure so that the control rod moves and adjusts the boost pressure.
11 At the moment when the control rod begins to move, read the pressure indicated on the pressure gauge. The pressure should be at least 0.4 bar (but not abnormally high).
12 If the pressure is too low, shorten the rod additionally until 0.4 bar is achieved.







13 Remove the pushrod and coat the pin on the operating arm with Molykote 1000, part no. 30 20 971, or the equivalent.
14 Fit the pushrod and clip, grip the pushrod with slip-joint pliers and lock the nut.
15 Remove the pressure gauge and pump.
16 Reconnect the hose to the diaphragm unit.







17 Fit the heat shield, coat its stud with Molykote 1000, part no. 30 20 971 or the equivalent, and screw on the nut.
18 Grease the O-ring with non-acidic vaseline and fit the bypass pipe.
Tightening torque: 8 Nm (5.9 lbf ft)