What are the reasons why a truck air pump cannot pump air?
3 Answers
Truck air pump cannot pump air for reasons including: softening of the built-in elastic piece in the air pump, blockage in the air pump pipeline, air leakage in one of the four circuits, etc. Below is a detailed introduction to these reasons: Softening of the built-in elastic piece in the air pump: After long-term use, the built-in elastic piece in the air pump loses its elasticity, leading to softening and inability to function properly. This results in the failure to establish effective air pressure during pumping. Blockage in the air pump pipeline: If there is a blockage in the air pump pipeline, it hinders the smooth flow of air, naturally making it impossible to pump air. Air leakage in one of the four circuits: This situation is relatively common. Due to air leakage, there is a loss of air pressure, which can be judged by sound.
I've been repairing trucks for over a decade and often encounter situations where the air pump fails to build pressure, primarily due to issues with the air compressor. It could be that the piston rings inside have aged and worn out, causing poor sealing which affects pressure buildup. Alternatively, there might be leaks in the system—check the air hose connections, dryer, or brake chambers; soapy water can help identify small bubbles. A loose belt in the drive section can also reduce compressor efficiency. I recommend starting with simple troubleshooting steps like replacing blown fuses or cleaning the air filter. If the air pump is noisy and overheats during operation, there's an 80% chance the compressor's own seals are damaged. Don't forget to check if the pressure regulator valve is stuck—if that part fails, it will result in weak air pressure. Insufficient air pressure can lead to brake failure, which is extremely dangerous, so it's crucial to get it professionally inspected immediately. Delaying until nighttime when the truck can't be driven would be disastrous. Regularly checking the system pressure gauge monthly can help prevent such failures.
I've been a truck driver for twenty years and have encountered the air compressor failing to pump air several times. Once on the road, the compressor suddenly stopped working, and it turned out the drive belt had snapped—replacing it solved the problem. Another time, there was an air leak in the system due to a small fitting that had aged and developed a hole; a temporary fix with tape got me to the repair shop. In cold winter temperatures, the air compressor is prone to freezing and clogging, but warming up the vehicle usually resolves it. I advise new drivers not to overlook maintenance of the braking system. A slow air pump directly affects brake response time, and once the air pressure drops below 6 kg, the brake pedal becomes stiff, which is extremely dangerous on highways. A simple check: after starting the engine, listen to the compressor—if there's a clicking sound but the pressure doesn't rise, it might indicate a system leak or a stuck valve. Make it a habit to inspect the dryer and filter monthly to prevent blockages.
