La Marzocco
Overpressure Brew Circuit
Brew pressure is too high (above ~10 bar) and shots run too fast or channel.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Pump bypass valve misadjusted, blocked expansion valve, incorrect pump installation, faulty pressure gauge reading low (apparent high pressure)
How to Fix / Troubleshooting
Safety first: Adjusting pump pressure should be done carefully. Turn OFF and unplug the machine before accessing the pump.
Steps:
- Verify with gauge: Use a portafilter pressure gauge to confirm actual brew pressure.
- Adjust pump bypass: Locate the adjustment screw on the rotary pump. With the machine running and gauge attached, turn the screw in small increments to set pressure to La Marzocco’s recommended value (typically ~9 bar).
- Check expansion valve: If pressure cannot be lowered, the expansion valve may be blocked. Remove and clean or replace it.
- Confirm gauge accuracy: If readings seem inconsistent, the panel gauge may be faulty and should be replaced.
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Repair Difficulty
Medium
3/5
Required Part
Pump Bypass Valve
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