Inspection Using Simplified Tester

Required Special Tool: 

• MB992146: Booster test adapter installer

1. Before starting this inspection, remove the brake booster check valve from the vehicle and check its operation (Refer to MASTER CYLINDER ASSEMBLY AND BRAKE BOOSTER ASSEMBLY  ).
2. After checking, install the check valve to the vacuum hose and connect it to the vacuum gauge. Install the booster test adapter (Special tool: MB992146) to the brake booster and connect it to the vacuum gauge. Connect the pressure gauge and pedal depression gauge as shown in the figure. Bleed the pressure gauge and then perform the following tests:
   1. Airtightness test with no load

      Start the engine, and stop it when the vacuum gauge indicator has reached approximately -67 kPa (-9.7 psi). The result is judged as "Good" when the drop of the vacuum approximately 15 seconds after the engine was stopped is within -3.3 kPa (-0.5 psi).

   2. Airtightness test with load

      Start the engine and depress the brake pedal with 200 N (45 lb). Stop the engine when the vacuum gauge indicator reached approximately -67 kPa (-9.7 psi). The result is judged as "Good" when the drop of the vacuum approximately 15 seconds after the engine was stopped is within -3.3 kPa (-0.5 psi).

      When one or more of the above check results are judged as "No Good", the vacuum hose or brake booster is suspected faulty.

   3. Brake booster characteristics test
      Fig 1: Installing Check Valve To Vacuum Hose

      Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

   Perform this test after the above (1) and (2) were performed.

   1. Non-servo effect test

      With the engine stopped, make sure that the vacuum gauge reading is 0 kPa (0 psi). Depress the brake pedal with 100 N (22.5 lb) and 300 N (67.4 lb), and measure the fluid pressure generated.

      STANDARD VALUE SPECIFICATION
      
      

      Item	Pedal depression force
      	100 N (22.5 lb)	300 N (67.4 lb)
      Generated fluid pressure kPa (psi)	0 - 600 (0 - 87)	1,030 - 2,220 (14 9 - 322)

   2. Servo effect test

      Start the engine. Depress the brake pedal with 100 N (22.5 lb) and 300 N (67.4 lb) when the vacuum gauge indicator reached approximately -67 kPa (-9.7 psi), and measure the fluid pressure generated.

      STANDARD VALUE SPECIFICATION
      
      

      Item	Pedal depression force
      	100 N (22.5 lb)	300 N (67.4 lb)
      Generated fluid pressure kPa (psi)	6,570 - 8,330 (95 3 - 1,208)	10,370 - 11,560 (1, 504 - 1,677)