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'98 Nissan 200 SX

The brake pedal has a lot of drift. With the engine running, I hear a double click sound when I step on the pedal and release it. With the engine off, I hear a noise similar to a fart or a cow mooing when I depress the pedal. When I pump the pedal it tightens up. I had to add a little brake fluid to the reservoir. I can’t see any leaks. What’s going on, and how can I fix it myself?

The click is probably the brake light switch. If the brake fluid level got too low there could be air in the system, which would need to be bled. A vacuum leak or a bad brake booster are also possibilities.

Thanks for the info. How can I discover a vacuum leak or determine if the booster(master cylinder?)is faulty?