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

MODEL 204, 207

Fig 1: Checking Brake Booster

Courtesy of MERCEDES-BENZ USA

MODIFICATION NOTES

16.9.09

Value modified: Bleed screw to brake caliper

Model 204 except model 204.077/277/9 Model 207

*BA42.10-P-1003-10J

	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
1	Eliminate the vacuum in brake booster (A7/7)	To do this, press the brake pedal several times with the engine switched off.
2	Open engine hood and raise to vertical position	Model 204
2	Open engine hood and raise to vertical position	Type 207	AR88.40-P-1000EW
3	Connect vacuum tester (030) to brake booster (A7/7) with test connection (031)		AR43.10-P-0024-01V
		Test specifications for brake booster	*BE43.10-P-1001-01F
		Test specifications for brake booster	*BE43.10-P-1002-01F
			Figure
			Figure
4	Connect pressure tester (051) with connection fitting to brake caliper	Use the correct connection fitting (pitch, taper etc.), otherwise leakage and measurement errors will occur.
4			*BA42.10-P-1003-10J
5	Attach pedal force meter (060) to brake pedal
6	Start engine and by opening the throttle produce a vacuum of 0.75 to 0.8 bar	If this vacuum is not reached or it drops immediately, the seal between the brake booster (A7/7) and master brake cylinder may be damaged or the check valve (17) in the vacuum line (8) may be defective: ↓
		Check non-return valve.	AR43.10-P-0023CW
		Remove/install master brake cylinder, replace gasket: Model 204	AR42.10-P-0300CW
		Model 207	AR42.10-P-0300EW
7	Apply the specified force to the brake pedal and read off the line pressure on the pressure tester (051)	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. The measured value must be within the value range.
7		Brake pipe line pressure	*BE43.10-P-1003-01F
8	Detach vacuum tester (030) with test connection (031) from brake booster (A7/7)
9	Detach pressure tester (051) with connection fitting from brake caliper
10	Remove pedal force meter (060)
11	Bleed brake system	Only bleed the brake caliper to which the pressure tester (051) was connected.
		Model 204	AR42.10-P-0010CW
		Model 207	AR42.10-P-0010EW
	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
12	Check brake system for leaks		AR42.10-P-0100-01V

PNEUMATIC BRAKE BOOSTER TEST SPECIFICATIONS

Number	Designation					Model 204	Model 207
BE43.10-P-1001-01F	Brake booster dia.			-	mm	203/203	203/203
BE43.10-P-1001-01F	Brake booster dia.			-	inches	8/8	8/8
BE43.10-P-1002-01F	Boost factor					≈5, 6	v5, 6
BE43.10-P-1003-01F	Brake pipe line pressure	Intake manifold vacuum 0.75...0.8 bar	Force on brake pedal	50 N	bar	16.7...23.7	16.7...23.7
				100 N	bar	33.3...42.9	33.3...42.9
				150n	bar	49.8...61.4	49.8...61.4
				200n	bar	66.3...79.8	66.3...79.8
				250n	bar	82.9...98.3	82.9...98.3

FRONT AXLE BRAKE CALIPER

Number	Designation		Model 204 except model 204.077/277/377/9	Model 204.077/277/377	Model 204.9
BA42.10-P-1003-10J	Bleed screw to brake caliper	Nm	14	14	14

FRONT AXLE BRAKE CALIPER

Number	Designation		Model 207
BA42.10-P-1003-10J	Bleed screw to brake caliper	Nm	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