LUCCA Tempo: Inspecting and Cleaning the Grouphead Solenoid

The grouphead solenoid (aka three-way solenoid) allows water to pass through the grouphead and releases pressure after pulling a shot or back-flushing. Inspect this if there is no water from the group but the pump gauge is still registering pressure.

Tools required:

• #1 Phillips head screwdriver
• #2 Phillips head screwdriver
• 10mm combination wrench
• 14mm combination wrench
• 22mm combination wrench
• 3mm Allen key

Optional (but convenient):

• Wire cutters
• Flat blade screwdriver - long shank
• 3mm hex driver - long shank T-Handle

Before continuing ensure the machine is fully cooled and disconnected from the power source.

1. First, remove the panels from the machine to reveal the grouphead solenoid, exhaust tubing, and other internal components.
   
   
2. Identify the grouphead solenoid.
   
3. Clip the zip tie with a pair of wire cutters. Gently slide the tubing off of the barbed fitting. Gently twist / wiggle the tubing to free it from the fitting by grasping directly on the fitting itself.
   
4. Use the 14mm wrench to disconnect the fitting from the solenoid armature. There are two places with tool flats - apply torque on the innermost fitting. There may be some resistance due to the application of factory thread sealant.
   
5. The solenoid coil is held on to the armature with a clip. This will slide off by applying tangential force with a flat blade screwdriver or similar. The following example uses a long shank flathead screwdriver with the top panel removed and the machine on its back.
   
6. Once the retaining clip has been removed, slide the solenoid coil off of the armature and set it to the side. It may be necessary to gently pull some wiring connections to the side via the top access panel.
   
7. Now the solenoid armature can be removed using the 22mm combination wrench. This may be quite snug - if a vice is accessible, it may be preferable to remove the entire assembly, clamp the flat sides of the base in the vice, and remove the armature outside of the machine (see Alternate Method below).
   
   
8. Remove the four 3mm socket cap screws using the 3mm hex driver or Allen keys.
   
   
   If these are too snug to easily remove with the T-driver, you may need the extra leverage provided by the shorter Allen key.
   
   Removing the top two screws may be easier from above, with the vibratory pump removed and set aside.
   
9. Inspect the apertures on the grouphead for any sign of debris:
   
   Hold the solenoid base up to the light to inspect for any obstructions within the solenoid gicleur:
   
   
   
   Inspect the sealing surface of the piston within the solenoid base for any signs of damage or wear:
   
10. Reassemble the solenoid. If desired, soaking the armature, sealing surface and solenoid base in warm water with a mild detergent solution may help loosen any residual coffee oils and help ensure proper function of the valve.
    
11. Reinstall the solenoid base onto the grouphead, paying particular attention to the orientation of the opening on the grouphead and solenoid base!
    

Alternate Method of Removing the Solenoid Aperture:

1. Clamp the base in a bench-top vice. Use a microfiber towel or disposable rag to prevent marring the surface.
   
2. Carefully apply torque to the solenoid aperture. If this is seized the release of force may be sudden when it finally breaks free! Be mindful of nearby objects to avoid injury.
   

See also:

• LUCCA Tempo: Priming the Vibratory Pump
• LUCCA Tempo: Replacing the Vibratory Pump