Welcome back to the Technicians’ Dispatch. In this edition, we’ll cover a very small but incredibly important serviceable part in the Linea Mini: the Flow Restrictor. This guide will provide you with the necessary insights and procedures to keep your machine running smoothly. Please note: This guide is only for swapping out the flow restrictor in the Linea Mini with serial numbers starting in ‘LM’.

swapping the linea mini flow restrictor

a step-by-step guide

what is a flow restrictor?

The gicleur, also known as the flow restrictor, is a tiny cylindrical piece of metal with a small orifice through it. The flow restrictor sits between the coffee boiler and the rest of the water’s path to the espresso machine’s brew chamber. The small diameter of the orifice limits the flow of water, slowing down the time it takes to fill the empty space between the dispersion screen and packed coffee puck as brewing starts.

Accessing this part is a complicated procedure and not just anyone should take on the challenge. If you feel unsure about this procedure, it is best to hire a professional La Marzocco recommended service partner to complete the task for you. An espresso technician will have access to pipes and fittings that may need to be replaced on the machine during the servicework. Keep in mind that fixing one thing can bring attention to or cause other parts to need replacement as well.

should I change my flow restrictor?

If you think you might have less water flowing from your machine’s grouphead, you can do a flow rate test to check! This test designed to assess whether or not the flow restrictor in the machine’s brew boiler assembly has become occluded with scale or other debris.

Flow Rate Test

the two most common reasons

  1. Clogged with scale. The flow restrictor’s orifice is tiny and it can quickly become clogged by scale build up, either from the machine being left on for 36 hours unused or from bad water quality. When a flow restrictor becomes clogged, the flow rate of water out of the group head will slow to a thin trickle. If clogged, it is best to swap it for a new one, rather than trying to clean it. 
  1. Espresso enthusiasts may want a smaller flow restrictor. The Linea Mini comes with a standard 0.8mm flow restrictor. Swapping the original 0.8mm flow restrictor to a smaller 0.6mm will reduce the flow rate of water to the brew chamber. While doing this will slow down the flow rate in the machine, it will also increase the likelihood of clogging the flow restrictor. The 0.8mm flow restrictor is the same size used on the commercial Linea Classic espresso machine, and works perfectly well. 

We will discuss two possible ways of completing a flow restrictor swap: front access and back access.

front-facing access (less invasive – requires bent nose pliers)

What tools are needed?

  • Socket set or adjustable wrenches 
  • Bent needle nose pliers
  • Hex Key Set
  • Molykote and a new o-ring
  • Philips head screwdriver
  • Rag 

Espresso machine must be turned off, cooled and depressurized(both gauges at 0) before the procedure can be done. 

  • Remove the large cup grate, the tray below it and the group head cover plate from the machine. (Note, there is a recessed screw in the cutout of the metal, that must stay when removing the top panel of machine) 
  • Remove the BREW PADDLE. 
  • Undo the four screws(using the hex key) that hold the top of the COFFEE BOILER in place and remove the top plate.
  • You will need BENT NEEDLE NOSE PLIERS to access the GICLEUR(#20) sitting inside of the BRASS MALE TO MALE FITTING(#11). 
  • Replace GICLEUR(#20) by gently screwing the new one gently into the BRASS FITTING(#11). The BRASS FITTING(#11) will remain connected to the COFFEE BOILER while you replace the GICLEUR(#20). 
  • Replace the COFFEE BOILER lid and o-ring(if necessary add Molykote to the o-ring) 
  • Replace the plate and 4 screws on top of the COFFEE BOILER.  
  • Replace brew paddle, grouphead cover, cup tray and grate. 

back-facing access (only for those techs savvy and familiar with compression fittings)

NOTE: The back access is risky because we have to work with and around the copper pipes, these parts are easily twisted and broken. The brass male to male fitting that holds the flow restrictor is also easily broken during removal. 

What tools are needed?

  • Socket set or adjustable wrenches 
  • Needle nose pliers
  • Hex Key Set
  • Molykote and a new o-ring
  • Philips head screwdriver (to remove top of machine)
  • Rag 

Espresso machine must be turned off, cooled and depressurized(both gauges at 0) before the procedure can be done. 

  • Remove the large cup grate and the tray below it.
  • Undo the TUBE COFFEE GROUP – BREWING SOLENOID V(#14). and the TUBE BREWING SOLENOID VALVE – DRAIN(#17) from the SOLENOID VALVE 3 WAY(#5) and the COFFEE BOILER (be careful of the copper pipes getting twisted and breaking) 
  • Slide the SOLENOID COIL(#13) off of the SOLENOID ROD(#7) 
  • Remove the SOLENOID PLUNGER(#4) and ROD(#7) from the SOLENOID VALVE (use your rag to catch any water that may leak out here) 
  • Then you will be able to unscrew the SOLENOID VALVE (Gold head part) from the COFFEE BOILER
  • Unscrew and remove the BRASS MALE TO MALE FITTING(#11). (use your rag to catch any water that may leak out here and be very careful not to break this fitting trying to get it out) 
  • Nestled inside the inner side of the BRASS MALE TO MALE FITTING(#11) we will find our GICLEUR(#20) (use needle nose pliers to gently unscrew and remove the GICLEUR) 
  • Replace GICLEUR(#20) by gently screwing the new one into the BRASS FITTING(#11) and connect it once again to the  COFFEE BOILER with the corresponding nut and washer.
  • Screw in the SOLENOID VALVE (Gold head part) and tighten with a wrench, but wait until you put on the SOLENOID PLUNGER(#4) and ROD(#7) to tighten all the way. (teflon tape can be used between the valve and the boiler if the valve does not line up correctly)
  • Reconnect the TUBE COFFEE GROUP – BREWING SOLENOID V(#14) and TUBE BREWING SOLENOID VALVE – DRAIN(#17) (again be careful of the copper pipes getting twisted and breaking) 
  • Replace cup grate and tray on top of the espresso machine

ready to brew again!

We hope this walkthrough helped you gain a better understanding of how to complete a flow restrictor swap in your Linea Mini. On the other hand, it may have got you thinking that you want an espresso technician to do the job for you and if so, that’s great too! If you feel unsure about this procedure, it is always best to hire a professional La Marzocco recommended service partner to complete the task.  

Reach out to the local La Marzocco Home Team in your area with any questions, we’re all here to help! 
Email: homesolutions.usa@lamarzocco.com

Written by Kimberly Franklin, La Marzocco Home Solutions