So my wife and I have a Delonghi EC155 espresso machine that we have used for years. Lately it's been having a lot of trouble pushing the water through the coffee. We can hear the pump pumping, but the water just barely drips out. We end up having to pull it 2 or 3 times to get a full shot (or just wait for the drips to fill up the shot glass).

I opened up this machine once before in the hopes of cleaning it, but found almost everything inside pretty clean and the plumbing is all sealed up. So I'm a little befuddled as to what to do next.

How do I fix my machine so that the shots come out in a single pull? I wonder if my pump just can form enough pressure anymore - can I measure the pressure?

A note on the grounds: We have the grinder set to the finest grind, which comes out like a fine sand. We've had it this way for a long time and not had any problems. We fill the basket to about 1/2 full (it's a double shot basket, and we only need one shot - the single shot basket was fed to the garbage disposal years ago) and tamp. I've been tamping more lightly recently, thinking that the problem was grounds that are too compressed to let the water through.


  • Sounds like the heater might be struggling to keep up with the pump; have you tried de-scaling? See also this question on slow espresso. Welcome to Coffee, I hope we can help!
    – hoc_age
    Commented Feb 8, 2016 at 20:28
  • 1
    yeah, I saw that question earlier. It didn't seem to fit with what I was experiencing. No, we haven't tried de-scaling - I'll research how to do that.
    – rothloup
    Commented Feb 9, 2016 at 0:58
  • The metal cup that holds your filter and grounds has a very tiny hole in it. Sometimes a rogue piece of coffee ground or shell gets past the filter and gets stuck in the hole, effectively blocking it, and preventing (or slowing) your machine from pulling a shot. I thought my machine's pump was broken until I figured out it was simply obstructed. A toothpick, needle, or a good smack should clear it out and allow your rapid return to full caffeination.
    – Brian D
    Commented Feb 8, 2021 at 23:56

12 Answers 12


As suggested in comment above, descaling or decalcifying your machine may solve your problem. We just run straight distilled white vinegar through ours to do so. Running the machine with distilled water rather than tap water helps keep mineral deposits to a minimum.

Also, running it without water can create an airlock (which makes it take a while for the water to pull through), and allows the pump to spin freely, and so can wreak havoc on, or at least weaken the pump. (I don't know what specific pump is employed by your machine, but this page may apply.)

Moreover, in the event that the pump has become weakened, it can be helpful to keep the reservoir completely full of water. I do not believe that a normally working machine would be affected too much by the grinding coarseness selected.

Edited to add: While commercial descaling/decalcifying solutions are available (and might work really well) for this application, the staff on a website selling such reports in the Q&A, "Breville actually recommends using vinegar to descale their machines while you're under their warranty."

When deciding what to use, it may be to one's advantage to research whether the product is under warranty, and what the specific manufacturer recommends. Also, take into consideration that the unlisted chemicals that might be found in a given solution could put off foul odors and/or flavors (not that vinegar makes a good perfume, by any means).

P.S. I just found out that the safety data sheet for one descaling liquid contains the following hazard warning (although the company might issue the same warning about vinegar if they sold it):

H315 Causes skin irritation.

H319 Causes serious eye irritation.

  • 1
    Thanks. We always use filtered water and rarely have run out of water (certainly not for an extended period). I'll try descaling it.
    – rothloup
    Commented Feb 9, 2016 at 1:29
  • So my wife tells me that she descaled it about 6 months ago using a vinegar solution based on some instructions we found online (might have been ehow.com or something like that). It didn't seem to help (the machine was starting to slow down back then, also, it's just gotten a lot worse now).
    – rothloup
    Commented Feb 9, 2016 at 1:48
  • She followed these instructions. 3oz vinegar per 20oz water.
    – rothloup
    Commented Feb 9, 2016 at 3:19
  • 2
    I recommend descaling with a descaler made for espresso machines. They are easily found online and the right strength for running through the machine. If that doesn't work, you may have waited too long and may need to disassemble the group head under the shower screen as my Gaggia machine often gets pretty crusted up there, one time I even had to chip it away. Commented Feb 12, 2016 at 21:42
  • 2
    Was the problem solved with descaling in the end?
    – lithic
    Commented Feb 13, 2017 at 19:57

Adjust the grind. Make it less fine.

Sounds like the pump is not strong enough to push water through the puck. Rather than set-and-forget on the finest it can do, you should be adjusting the grind constantly: after every shot if it ran longer than 25 seconds (to get 30ml) make the coffee a little bit more coarse, if shorter than 25s then make the coffee a little finer. Every new batch of coffee beans you'll need to run a couple of shots, and perhaps make big changes, to re-calibrate to the nature of the new beans.

Factors that play into this equation include:

  • how much coffee you put into the basket (more coffee requires a coarser grind)
  • how hard you tamped it (packing it harder invites a coarser grind)
  • how fresh the beans are (as they age they dry out, inviting a finer grind as they age)
  • how oily or dry the beans appear to be ('shiny' roasts tend to invite a coarser grind than ones where the surface of the beans appears light and dry)
  • humidity (dry air helps the grinder get a fine grind, so dry air invites a coarser grinder setting, humid air invites a finer setting on the grinder)

This all assumes there is water in the tank and the filter is clean and clear of course.

  • Now there's someone who's done this before! Commented Feb 12, 2016 at 16:38

I Googled "how to disassemble delonghi ec155" and found a website that said to:

  • Take the screen off (the one above the coffee grounds). I have done this when I descale, but there is a brass screw you can take out with a flat head. Take the little spring behind it out.

  • Clean all that with vinegar. I used a q-tip with vinegar to clean up in there.

My machine works now!

Be careful not to damage the little clear bubble-like thing on the spring.


A couple of thoughts..

Do you use both baskets that came with the espresso machine? The EC155 comes with a single shot and double shot basket. They are pressurized, so if the pressure regulator at the base of the basket is fouled up, it could be preventing water flow. If you have an unused basket, you could try pulling shots with it to see if water flow is improved.

Does water flow freely with the portafilter removed completely? If not, then you may have something restricting flow in the screen directly above the portafilter. You can typically remove this to replace seals, and it may need a good scrubbing.

Any thoughts on backflushing an EC155? I've never done it, but was shocked with how much oil / espresso nastiness came out when I backflushed my Rocket for the first time. I'm not sure you can backflush an EC-155, as I'm not sure where the built up pressure would be diverted to..

If the screen at the group head looks clean, then I might move on to descaling.


I ended up changing the pump and the plastic valve that goes between the pump and the boiler. I also cleaned out the screen that screws to the bottom of the boiler which was almost completely blocked with gunk. I used a pin to open all the holes on that.

After all that I have full pressure again. I am not sure what the main problem was. Probably the gunked up screen at the bottom of the boiler. I probably didn't have to change the pump or the valve but I didn't notice that screen till after I took everything apart. If I had just RTFM I would have noticed that it tells you to clean that screen in the manual.


I happen to have the same EC155 machine, and ran into similar problems - the coffee just didn't make it through the filter, but the pump was working, when filter removed. The culprit was the filter itself - it is more complex, than I thought before. First, the metal sieve needs to be cleaned thoroughly, until no clogged holes left - I did it the hard way, with small needle, in front of the window. The second, there is a plastic plate with a plastic screw in the center. It has a peculiar small "valve" in the center, which was actually clogged. I don't know the best procedure, but moving it around in it's place with a tip of the knife helped - the machine finally began to work like new! Descaling does not help with clogged filter, only cleaning. Also, DO NOT use fine ground coffee with this machine, it clogs the filter like mad!

  • Don't use find-grind coffee in an espresso machine?? Sounds like blasphemy. :) You clearly have a method for cleaning this machine; thank you for the nice overview. Out of curiosity, did it seem that the clogging was caused by coffee, or mineral/scale deposits, or both? Welcome to Coffee!
    – hoc_age
    Commented Jun 30, 2017 at 0:18
  • +1 for cleaning the group head screen; this may well have been part of the OP's problem (it was for me). A needle may not be necessary: the deposits on the screen are oily, and rubbing some dishwashing liquid onto the screen whilst holding it under some running water should do the trick.
    – Kahovius
    Commented Mar 15, 2020 at 21:55

Our Mr Coffee Espresso machine is 3 years old. A great little machine, but the coffee drip started coming out VERY slowly. We cleaned it throughly but to no avail. Then we finally tried a mixture of 3/4 c. water to 1/4 cup vinegar (3:1) through a cycle and after what sounded like a sudden "poof" IT WAS FIXED! There was something clogged in there, and the vinegar was the trick! The coffee stream is back to normal.


Ok I had this problem and called them and they helped fix it, here's what you do: - open the coffee lid, - put a new cup under and press brew coffee, while coffee grinds, turn the coffee grindness (inside coffee storage area) all the way up to 7. - brew 2-3 cups and it should work again

The issue I'd when coffee grinds are very fine it takes much longer for water to pass through.


I have seen now with two of my BAR32 retro's that the small inside filter (part number 5513220521) was the culprit. It is at Delongies website delonghi.encompass.com around $2.60, while on Amazon around $10. Open the machine bottom with a special security tamper torx bit and you see the filter. It is most likely dark inside which means molt, dirt etc. Replace it and many issues with water flow will go away after you in addition de-calcium the whole system.


Check this link out.This guy has a clever idea on how to measure the pressure coming out of your espresso machine. He uses an inner tube of a bike tire, and a pressure gauge. Sounds a little questionable but cool none the less.

Here is another thread from home barista that talks about measuring espresso pressure with a portafilter pressure gauge.

To get a proper shot of espresso you need 9 bars of pressure consistently for 20-30 seconds.

Happy Coffee!


99% The problem is in the filter basket itself, not the pump or the inner tubes (however, making a descaling is always a good idea).

For another 1% - check Nate M's answer to ensure that it's not something else - "Does water flow freely with the portafilter removed completely?"

If the problem is in filters indeed as I assume, than you need to clean them like shown in the manual - see figure 22 and further here http://101coffeemachines.info/wp-content/uploads/2017/12/delonghi-ec155.pdf If they are completly stuck, you may need to buy new ones, modern filters with double floor will fit.

P. S. The ULKA vibrating pumps that is installed on this machine is either working or not. This, it's VERY unlikely that you hear the pump, but it doesn't work.

P. P. S. The "golden brewing time" that Better Coffee is reffering to above describes the brewing process on unoressurized filters on proffesional machines with wide groups. On your Delonghi EC155 you have pressurized filters and small 51m diametr filters, so your brewing time don't have to be the same.


One of the issues with lower flow of water through the ground coffee is that the beans have been ground too fine, from what my local Barista tells me, that they should be "grounds" not powder! Too course and water will flow faster and produce weaker coffee, too fine and its difficult for water to pass through, when you remove the filter holder, the remnants should not be 'muddy and wet' but firm and dryish. If you grind your own coffee, use a quality variable texture grinding machine. Also compare with commercially ground coffee which is normally like fine beach sand.

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