Why is my espresso machine making a loud pumping or hissing sound?

A brief pumping sound can be normal when the machine first moves water through the system, but persistent loud noise or hissing can point to air in the appliance, a steam control issue or poor water flow. Manual espresso machines should be used with care because they heat water and produce pressure. If the sound is accompanied by leakage, burning smells or unstable operation, stop using the machine.

1. Check that the tank is filled and seated correctly. Expected result: the pump should draw water smoothly once the tank is properly fitted.
2. Confirm that the steam control is closed before brewing. Expected result: water should go through the coffee path rather than escaping as steam or hiss.
3. Run a short flush with plain water to remove trapped air. Expected result: the loud sound should reduce once the system is primed.
4. Check the filter holder and coffee dose. Expected result: water should pass through at a steady pace instead of forcing through a packed basket.
5. Listen for a change after a few seconds of operation. Expected result: a normal startup noise should become quieter once air is cleared and water is moving freely.

Stop using the product if hissing continues, steam escapes unexpectedly or the appliance becomes hot in a way that feels unsafe. If the noise remains unresolved, contact the retailer or store where the product was purchased.