Spring 0.5x7x13.5mm

Small compression spring, part of the check valve in the AZ-type pump. Works together with the check valve plug, pressing the blocking element against the seat.

Application

The spring presses the ball or blocking element of the check valve against the seat, preventing water from flowing back toward the pump inlet after the gun is closed. It works directly at the check valve plug (43.009) in the same seat.

Symptoms – when to replace

• The pressure gauge shows a pressure drop with the gun closed, even with a sound, recently replaced check valve plug.
• The pump runs unevenly or jerks on startup after standing idle for a while.
• The spring is visibly weakened, shortened or deformed when the check valve is disassembled.
• Check valve leak symptoms return shortly after replacing the plug alone, without replacing the spring.

How to choose the right part

Selection is based on reference number 43057 and the 0.5x7x13.5mm size – the spring is designed exclusively for the AZ-type pump and does not fit check valves in AM or AQ pumps.

When replacing the spring, also assess the condition of the check valve plug (43.009) and its O-ring in the same seat – check valve leak symptoms rarely result from a single component.