Gaggia Classic Pro: Steam Valve Leak Test
by Whole Latte Love
2 min read
Updated: January 7, 2026
Before assuming there is a problem with the valve, it is important to confirm whether the water coming from the steam or hot water wand is an actual leak or simply a normal drip caused by residual pressure and vacuum in the line.
Some light dripping after using the wand is expected and normal. This occurs as pressure equalizes inside the machine. In the video below, Ted explains what normal dripping looks like and how to determine whether the valve is truly leaking or operating as designed.
Important: When water is seen dripping from the wand, the natural reaction is often to tighten the knob. This should be avoided. Overtightening the knob can damage the internal valve seal and make the issue worse.
Symptom: Full Flow from the Wand with the Knob Closed
If you are seeing full or continuous flow from the wand even when the knob is fully closed, this is not normal behavior. One common cause is a stripped steam or hot water knob.
The knob connects to the valve stem, and if the internal splines are stripped, the knob may turn without actually closing the valve.
How to Check if the Knob Is Stripped
Gently pull the knob straight away from the machine to slide it off the valve stem.
Inspect the back side of the knob where it connects to the valve.
If the internal plastic or metal splines appear rounded, cracked, or worn, the knob is stripped.
A stripped knob will need to be replaced, as it cannot properly close the valve.
Checking the knob should be done before assuming the valve itself has failed, as a stripped knob can mimic the symptoms of a leaking valve.
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