Pressure relief noises when brake pedal is released - AF42.46-P-1100AG

MODEL 230 except CODE (228) Stationary heater 

Damage code	Cause	Remedy
43 154 38	Micro-bubbles at valve seats in hydraulic unit can lead to cavitation and noises (noise when releasing brake pedal). The noises occur on the hydraulic unit; subjectively, however, they are heard in the vehicle as if they came from the right rear.	This remedy affects exclusively  noise complaints when releasing the brake pedal Other noises, e.g. when actuating the brake pedal, can not  be eliminated with this remedy.
	By using a threaded bolt, it is possible, beginning immediately, to install the modified bracket without removing the hydraulic unit. Please observe the modified parts ordering note!	IN THE INSTRUCTIONS DESCRIBED BELOW, ONLY THE BRACKET FOR THE SBC HYDRAULIC UNIT IS TO BE REPLACED. NEVER REPLACE THE SBC HYDRAULIC UNIT!
		1 Replace bracket for Sensotronic Brake Control (SBC) hydraulic unit.
		2 Lock vehicle globally. Leave locked during entire operation.
		3 Remove right air intake pipe.
		4 Remove vent line to radiator expansion tank.
		5 Remove retainers for hydraulic lines in area of SBC hydraulic unit.
		6 Loosen tie strap for electrical line on SBC bracket.
		7 Disconnect plug for SBC hydraulic unit.
		8 Lift SBC hydraulic unit slightly.
		9 Unscrew old SBC bracket from SBC hydraulic unit.
		10 Screw the short side of the threaded bolt (figure 2) included with the new bracket (figure 1) into the SBC hydraulic unit and tighten to approx. 12 Nm.
		11 Attach the new SBC bracket with collar nut (approx. 12 Nm).
		12 Position SBC hydraulic unit with bracket in rubber bushing on body.
		13 Install in the reverse order.

Figure 1 

SBC hydraulic unit bracket 

Fig 1: Identifying SBC Hydraulic Unit Bracket

Figure 2 

Threaded bolt 

Fig 2: Identifying Threaded Bolt