Checking brake booster - AR43.10-P-0325T

MODEL 211, 219 with Adaptive Brake (ABR)

Fig 1: Checking Brake Booster

Courtesy of MERCEDES-BENZ USA

MODIFICATION NOTES

29.7.09	Value changed: bleed screw to brake caliper		*BA42.10-P-1002-10B
	Value changed: bleed screw to brake caliper		*BA42.10-P-1002-10H

	Checking
	Risk of poisoning caused by swallowing brake fluid. Risk of injury caused by brake fluid coming into contact with skin and eyes.	Only pour brake fluid into suitable and appropriately marked containers. Wear protective clothing and eye protection when handling brake fluid.	AS42.50-Z-0001-01A
	Brake fluid notes		AH42.50-P-0001-01A
	Notes on repairs to brake system		AH42.00-P-0003-01A
1	Operate the brake pedal several times when the engine is switched off	In order to reduce the vacuum in the brake booster (1).
2	Remove the left cover in the engine compartment
3	Connect vacuum tester (01) with test connection to brake booster (1)		AR43.10-P-0024-01V
		Brake booster diameter	*BE43.10-P-1001-01A
		Boost factor	*BE43.10-P-1002-01A
		Vacuum tester	Fig 2
		Test connection	Fig 3
4	Remove front wheel
	Remove/install wheels	Model 211	AP40.10-P-4050Z
	Remove/install wheels	Model 219	AP40.10-P-4050TX
5	Connect pressure tester (02) with connection fitting to brake caliper and bleed	Pressure testers (02) for hydraulic oil systems must not be used for systems with brake fluid otherwise the brake fluid is mixed with mineral oil which can lead to failure of the brake. Use the correct connection fitting (pitch, taper etc.), otherwise leakage and measurement errors will occur. Follow the manufacturer's operating instructions in order to avoid incorrect operation and measurement errors. Model 211:
		Bleed screw to brake caliper	*BA42.10-P-1002-10H
		Model 219:
		Bleed screw to brake caliper Pressure tester (hydraulic single/dual circuit brake systems)	*BA42.10-P-1002-10B
6	Connect pedal force measuring instrument (03) at brake pedal
6		Pedal force meter
7	Start engine and by opening the throttle produce a vacuum of 0.75 to 0.80 bar	If a vacuum is not attained or it drops immediately, the seal between the brake booster (1) and master brake cylinder may be damaged or the check valve (2) in the vacuum line (3) may be defective: ↓ Test check valve (2), if necessary replace vacuum line (3):
		Model 211 with engine 273	AR43.10-P-0355T
		Model 211 except engine 273 Model 219 with engine 156, 272, 273, 642 If check valve (2) is OK replace seal between brake booster (1) and master brake cylinder: ↓
		Remove/install master brake cylinder.	AR42.10-P-0300T
8	Apply the specified force to the brake pedal and read off the line pressure on the pressure tester (02)	In order to cover measurement errors (incorrect force on the brake pedal, incorrect vacuum) and scatter of the measuring devices, a tolerance of ±10 bar on the specified value is permissible.
8		Brake pipe line pressure	*BE43.10-P-1003-01A
9	Remove vacuum tester (01) from brake booster (1)	Vacuum tester	Fig 2
9	Remove vacuum tester (01) from brake booster (1)	Test connection	Fig 3
10	Disconnect pressure tester (02) with connection fitting from brake caliper
11	Remove pedal force meter (03) from brake pedal
12	Bleed brake system	Only bleed the brake caliper to which the pressure tester (02) was connected.	AR42.10-P-0010T
13	Mount front wheel
	Remove/install wheels	Model 211	AP40.10-P-4050Z
	Remove/install wheels	Model 219	AP40.10-P-4050TX
	Risk of accident caused by vehicle starting off by itself when engine is running. Risk of injury caused by contusions and burns during starting procedure or when working near the engine as it is running	Secure vehicle to prevent it from moving by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.	AS00.00-Z-0005-01A
14	Check brake system for leaks		AR42.10-P-0100-01V

PNEUMATIC BRAKE BOOSTER TEST SPECIFICATIONS

Number	Designation					Model 211 with ABR [Adaptive Brake]	Model 219 with ABR
BE43.10-P-1001-01A	Brake booster dia.			-	mm	203/228	203/228
BE43.10-P-1001-01A	Brake booster dia.			-	inches	8/9	8/9
BE43.10-P-1002-01A	Boost factor					7.0	7.0
BE43.10-P-1003-01A	Brake pipe line pressure	Intake pipe vacuum	Force on brake pedal	50 N	bar	28...45	28...45
		0.75...0.8 bar		100 N	bar	55...70	55...70
				150 N	bar	80...95	80...95
				200 N	bar	102...118	102...118
				250 N	bar	115...122	115...122

FRONT AXLE BRAKE CALIPER

Number	Designation		Model 211 except model 211.076/077/276/277	Model 211.076/077/276/277
BA42.10-P-1002-10H	Bleed screw to brake caliper	Nm	14	14

FRONT AXLE BRAKE CALIPER

Number	Designation		Model 219.372/376/377	Model 219.322/354/356/357/375
BA42.10-P-1002-10B	Bleed screw to brake caliper	Nm	14	14

Fig 2: Identifying Vacuum Tester (201 589 13 21 00)

Courtesy of MERCEDES-BENZ USA

Fig 3: Identifying Test Connection (168 589 08 63 00)

Courtesy of MERCEDES-BENZ USA