back flush..


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Staff member
Aug 14, 2003
Boca Raton
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Went to a buddies coffee shop today. The guy who he is buying coffee from told him not to ever back flush his espresso machine with chemicals. Has anyone ever heard this before?? So I brought him some cleaner to back flush his machine. I started the process...but it didn't back flush. Put the blind filter in and product, pushed the button...waited 5 seconds then turned it off for 3 trying to get back pressure...nothing. When I took the port-a-filter out of the group head it almost exploded..why would the machine not back flush...any thoughts


Active member
Aug 11, 2004
Des Moines, Iowa
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His 3 way group head solenoid valve is most likely plugged on the dump side. The easiest way to see if this is true is just to take it off and look at it. All you need for the job is a metric number 3 Allen wrench, number 14 open ended wrench, 10" Adjustable Pliers, and a Crescent wrench 8 or 10" just needs to be able to open between 20 to 30mm.

Shut off the water to the machine, shut off power to machine, and drain off steam pressure (only needed if you don't want 2 - 4 ounces of hot water back tracking on you from the heat exchanger). Remove the dump tube with the number 14 wrench as well as the nut, lock washer, and washer from the solenoid. Remove the two Allen screws on the opposite corner of the valve body, they might have put 4 in there. After you get the valve off grab the body with adjustable pliers and the valve stem with the Crescent wrench. Remember lefty lucy righty tighty.

Once apart the shuttle and spring should pop right out with no hindrance. If it doesn't take your espresso machine cleaner and some hot water from the coffee machine. Use about a tablespoons worth of cleaner and a small steaming pitcher, soak the valve for 10 minutes. If it still doesn't move your going to need to replace it. You can get blockage in the stem of the valve and in the seat. So check that brass valve block to make sure the holes are open. You can throw it in the solution to help clean it up as well.

After you clean it up just rinse it off with clean water and reassemble. Put it on the opposite of the way you took it off.

You might want to check the instructions on the back of your cleaner. Most cleaners say you should run the first cycle between 10 to 15 seconds to help dissolve the cleaner. Then shut it off for 10 seconds. Turn it on for 5 to 10 seconds and repeat 5 times. Rinse portafilter and repeat with clean water to help rinse the group head.

From my dealings with a lot of other Roaster/Repair people I've heard this same problem over and over. They were told not to clean the machine with chemicals or they were told not to clean it every day, or they were told to clean it only once a week. This is very bad for anyone who makes more then a few drinks a day as that espresso will eventually build up a layer that will either cause the valve to fail or the group head.

Your problem sounds more like a valve. But if you reinstall the valve and the machine still has the same problem then the group head is most likely plugged. Some group heads are not able to be easily cleaned. There are a few that I've just said the heck with it and just replaced it. Those tend to run the operator as much as $500 to replace not including another $80 for the valve. Not cleaning your group is just stupid and in my opinion is how a lot of bad people make their money. Its like your car mechanic telling you that its okay to drive your car 10,000 miles after every oil change and never to bother checking your oil level between changes. If you were to take his advice 60,000 miles down the road your going to start having some pretty nasty issues to deal with. That is just not the way to see repeat business.


Well-known member
Aug 15, 2005
Central North Carolina
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Yeah your friend needs to pay no mind to negative info such as that. All machines equipped with 3-way solenoids need to be backflushed to maintain proper function. Be it a commercial or home machine. Personally I don't backflush with detergent every single day, but do so at least 1-2 times weekly. BUT I do clean water backflushes several times daily. Also important is pulling any shower screens, dispersion discs, etc. and soaking them in a detergent solution, along with baskets, portafilters. Groups need to be cleaned often or function, taste, etc will most certainly suffer. Later!