XJ-6 L6-4.2L (1983)
Vacuum Brake Booster: Testing and Inspection
The following tests on the vacuum system should only be performed if the hydraulic system is in satisfactory condition.
1.
Raise and support front of vehicle. Be sure one wheel will rotate freely.
2.
Start engine and allow vacuum to accumulate.
3.
Apply brake pedal several times. Be sure wheel is free to rotate immediately after pedal is released.
4.
If brakes bind, booster is faulty.
5.
With engine running, apply brake pedal several times and check operation of pedal.
6.
If response is sluggish, check condition of vacuum hoses and booster unit air filter.
7.
Allow vacuum to build up, then switch off engine and operate brake pedal.
8.
Pedal should be vacuum assisted for approximately three applications. Any less indicates a leaking vacuum system or an inoperative check valve.
9.
With engine switched off, operate brake pedal several times to evacuate any vacuum left in system.
10.
While maintaining light pressure on brake pedal, start engine. If booster unit is operating correctly, pedal will fall under existing pressure.
11.
If pedal remains stationary, there is a leak in the vacuum system.
12.
With engine running, apply and hold brake pedal. Switch engine OFF. If pedal rises against foot pressure, booster is faulty.
