How do you check your brake booster on your 1987 Volvo 240?

To check the brake booster on your 1987 Volvo 240, start by turning off the engine and pumping the brake pedal several times to deplete any residual vacuum. Then, hold the brake pedal down and start the engine; the pedal should drop slightly as the booster engages. If it doesn't drop or you hear a hissing noise, the brake booster may be faulty. Additionally, inspect the vacuum hose for any cracks or leaks that could affect performance.