Finding and correcting braking-system air leaks can keep you safe and in service
The basics
The air-brake system has three sections: the supply portion, the parking brake and the service brakes. The parking brake system has air pressure inside only when the parking brakes are released, while the service brakes have air only when applied.
Regular servicing of the air dryer helps prevent leaks by keeping the various system valves in good condition.
The most basic symptom of system leakage is a compressor that spends too much time running.
You’ll hear the compressor cut in and then hear an audible blast of air as it cuts out.
Another symptom is when you lose all pressure overnight with the engine off.
If you hear compressor cycling while sitting in traffic with a constant brake pressure, or when idling with parking brakes applied, the air-supply part of the system is leaking.
