Acura RL. Manual - part 378

BRAKE BOOSTER TEST

FUNCTIONAL TEST

1. With the engine stopped, press the brake pedal several times to deplete the vacuum reservoir, then

press the brake pedal hard, and hold it for 15 seconds. If the brake pedal sinks, either the master
cylinder is bypassing brake fluid internally, or the brake system (master cylinder, lines, modulator, or
caliper) is leaking.

2. Start the engine with the brake pedal pressed. If the pedal sinks slightly, the vacuum booster is

operating normally. If the brake pedal height does not vary, the booster or check valve is faulty.

3. With the engine running, press the brake pedal lightly and shift the transmission to the D position.

Apply just enough pressure to hold back automatic transmission creep. If the brake pedal sinks more
than 10 mm (3/8 in.) in 3 minutes, the master cylinder is faulty. A slight change in brake pedal height
when the A/C compressor cycles on and off is normal. (The A/C compressor load changes the vacuum
available to the booster.)

LEAK TEST

1. Press the brake pedal with the engine running, then turn OFF the engine. The brake pedal height

should not vary while pressed for 30 seconds. If the pedal height rises, go to step 6. If the pedal does
not rise, or varies go to step 2.

Fig. 36: Identifying Master Cylinder Components
Courtesy of AMERICAN HONDA MOTOR CO., INC.

2007 Acura RL

2005-08 BRAKES Conventional Brake Components - RL

Friday, June 05, 2009 3:00:06 PM

Page 25

2. Start the engine, and let it idle for 30 seconds. Turn the engine off, and wait 30 seconds. Press the

brake pedal several times using normal pressure. When the brake pedal is first pressed, it should be
low. On consecutive applications, the brake pedal height should gradually rise. Does the pedal rise on
each consecutive application? If it rises the booster is OK. If it does not, go to step 3.

3. Disconnect the brake booster vacuum hose (check valve built-in) (A) at the booster side.

Fig. 37: Identifying Brake Booster Vacuum Hose
Courtesy of AMERICAN HONDA MOTOR CO., INC.

4. Start the engine, and let it idle. There should be vacuum available. If no vacuum is available, the

check valve is not working properly. Replace the brake booster vacuum hose and check valve, and
retest. If vacuum is found, go to step 5.

5. Reconnect the vacuum hose to the brake booster.

6. Start the engine, and then pinch the brake booster vacuum hose between the check valve and the

booster.

7. Turn the engine off, and wait 30 seconds. Press the brake pedal several times using normal pressure.

When the brake pedal is first pressed, it should be low. On consecutive applications, the brake pedal
height should gradually rise.



If the pedal position does not rise, inspect the seal between the master cylinder and booster. If
the seal is OK, replace the brake booster.



If the brake pedal position varies, replace the brake booster vacuum hose/check valve assembly.

BRAKE BOOSTER PUSHROD CLEARANCE ADJUSTMENT

Special Tools Required

Booster piston holder 070AB-SJA0100

NOTE:



Brake booster pushrod-to-piston clearance must be checked and
readjusted before installing the master cylinder.



The master cylinder assembly comes with the specific plate that
adjusts the clearance between the brake booster and the specific
master cylinder piston.



Every time you change the master cylinder; use only the enclosed plate
to check the brake booster pushrod clearance.

2007 Acura RL

2005-08 BRAKES Conventional Brake Components - RL

Friday, June 05, 2009 3:00:06 PM

Page 26

1. Measure the clearance between the plate (A), supplied with master cylinder, and the brake booster

pushrod (B). Make sure that the enclosed plate touches contacting, surface (C) between the master
cylinder and brake booster. If there is a gap between the tip of the plate and the pushrod (D) or a gap
between the contacting surface and the plate (E), go to step 2.

Fig. 39: Measuring Clearance Between Plate And Brake Booster Pushrod
Courtesy of AMERICAN HONDA MOTOR CO., INC.



Do not use anything other than the enclosed plate to check the
clearance. Make sure to discard the plate supplied with master cylinder
after its use.



Brake booster has to be on the vehicle before the adjustment.



If the brake booster pushrod and yoke were removed as an assembly,
measure the pushrod reference valve (A), and adjust the yoke as
needed before installing the brake booster. In some situations, install
the yoke after installing the brake booster, then adjust the brake pedal
height.

Fig. 38: Adjusting Brake Pedal Height With Torque Specifications
Courtesy of AMERICAN HONDA MOTOR CO., INC.

2007 Acura RL

2005-08 BRAKES Conventional Brake Components - RL

Friday, June 05, 2009 3:00:06 PM

Page 27

2. Use the special tool to hold the nut, and turn the 6 mm pushrod (A) clockwise or counterclockwise to

adjust the pushrod inward or outward.

Fig. 40: Turning Pushrod
Courtesy of AMERICAN HONDA MOTOR CO., INC.

3. Install the master cylinder (see MASTER CYLINDER REPLACEMENT ).

BRAKE BOOSTER REPLACEMENT

1. Remove the master cylinder (see MASTER CYLINDER REPLACEMENT ).

2. Disconnect the vacuum hose (A) from the brake booster (B).

Fig. 41: Identifying Vacuum Hose And Brake Booster
Courtesy of AMERICAN HONDA MOTOR CO., INC.

3. Remove the engine wire harness (A) from the harness brackets (B), and move the engine wire harness

aside.

2007 Acura RL

2005-08 BRAKES Conventional Brake Components - RL

Friday, June 05, 2009 3:00:06 PM

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