If your espresso machine hums or buzzes but no water reaches the group head, start with the two free fixes: re-seat the water tank and purge the airlockby running the steam wand with the tank full until water comes through. Between them those two account for the large majority of "won't pump" calls, and both take two minutes. Only after those should you think about limescale, and only after that should you think about the pump.
The useful distinction before you start: this page is about a machine that moves no water. If water comes out but the shot gushes, drips or the pressure gauge sits wrong, that is a different fault tree — espresso pressure problems is the page you want. And if water comes out around the portafilter rather than through it, see espresso machine leaking from the portafilter.
Work through these in order
1. Is there water in the tank, and is the tank seated?Obvious, and still the single most common cause. A tank that is sitting a few millimetres proud does not engage the intake valve, and most machines give you no warning — they just run dry. Lift the tank out completely and push it back down firmly until it stops. On Breville machines check the tank is pushed fully home at the back; on De'Longhi machines check the lid is not holding it up. Some machines have a float or magnet in the tank that must be present and free.
2. Purge the airlock. This is the fix people have never heard of and it solves most of the rest. A vibratory pump moves water by vibrating a piston against a spring — it is not self-priming in any strong sense, so if an air pocket forms in the intake line the pump has nothing to push against and simply buzzes. It happens after you run the tank dry, after you refill, after transport, or after the machine has sat unused.
To clear it: fill the tank, turn the machine on, then open the steam valve and run the hot-water or steam function. The steam path is usually a shorter, lower resistance route than the group head, so water will often come through there first and drag the air out with it. Let it run for twenty to thirty seconds. Then close the valve and run the group. If nothing happens, repeat it two or three times — this frequently needs more than one attempt. On machines with a separate hot-water tap, use that.
3. Check the intake filter and hose in the tank.Pull the tank out and look at the intake — there is usually a small mesh filter, a silicone hose, or both. Mesh filters block with mineral debris and with bits of the tank's own plastic. The hose can kink or pop off its fitting, especially after the tank has been removed roughly. Rinse the mesh, straighten the hose, re-seat it.
4. Run it with no portafilter, and then with a blind basket. This isolates where the blockage is. With the portafilter removed entirely, run the brew function. If water comes out of the group head, your problem is downstream — a blocked basket or a blocked shower screen, not the pump. A basket whose holes are clogged with coffee oil and fines genuinely can stop flow altogether, and it is misdiagnosed as a pump fault more often than you would think; how to clean a portafilter covers the soak, and a puck screen that has never been cleaned does the same thing.
5. Suspect limescale. If you have had the machine a while, you live somewhere with hard water, and this came on gradually — slower and slower until it stopped — then scale is the likely answer. Dissolved calcium and magnesium precipitate out of water when it is heated and build up inside the boiler, the solenoid valve and the narrow passages of the group head. The narrow passages are what block first.
The fix is a descaling cycle with an acid descaler, not a cleaning tablet — those are alkaline detergents for coffee oil and they do nothing to scale. How to descale an espresso machine is the full procedure, and cleaning vs descaling explains why the two chemicals are not interchangeable. If the machine is badly scaled you may need two cycles with a soak between them, and on a machine that has stopped completely it is worth leaving the descaling solution sitting in the boiler for half an hour rather than cycling it straight through.
6. Check for a stuck or mis-set OPV, if your machine has one. The over-pressure valve dumps excess pressure back to the tank. If it sticks open, the pump circulates water back to the tank instead of pushing it through the coffee — the pump runs and the group stays dry. The tell-tale is water visibly returning into the tank while the pump runs. This is a repair job rather than a two-minute fix, but it is a cheap part.
7. Consider the pump itself — last.Vibratory pumps do fail, usually after years, and the symptom is a machine that makes its usual noise and moves nothing even after a successful airlock purge and a descale. A dead-quiet machine that makes no noise at all is more likely an electrical fault — a thermal fuse, a switch, or the pump's own wiring — than a worn pump. Ulka vibratory pumps are a standard part and inexpensive on the machines this site covers, and on a Gaggia Classic or a Rancilio Silvia replacing one is well-documented work. On a sealed super-automatic it is a service job.
Two things not to do
Do not run the pump repeatedly while it is dry. A vibratory pump is cooled and lubricated by the water passing through it. Running it dry for minutes at a time while you troubleshoot is how a recoverable airlock becomes a dead pump. Work in bursts of twenty to thirty seconds with pauses.
Do not descale with vinegar on a machine with brass or aluminium internals. It is a popular suggestion and a bad one: vinegar is a weak acid at an uncontrolled concentration, it is aggressive to some seals and platings, and the smell is nearly impossible to flush out of a boiler. A proper descaler is a couple of dollars per cycle and is formulated for the metals in coffee machines — best espresso descaling solutions has the options.
Stopping it happening again
Two causes are within your control, and both are water.
Never run the tank dry. This is the behaviour that causes most airlocks, and it is the easiest habit to change. Refill at a quarter rather than at empty.
Control what goes in the tank.Scale is a function of your water's mineral content, and there is a wide range across a single country — so the first step is finding out what yours is, with a TDS meter or your utility's water-quality report. If it is hard, you have three options: filter it, buy water formulated for espresso, or descale often. The third works but it is the one that shortens the machine's life. Water for espresso covers the chemistry — including why fully soft or distilled water is also wrong, because espresso needs some mineral content to extract properly — and best espresso water filters ranks the hardware.
The three products below address exactly those two causes: a descaler to clear scale that has already formed, a meter to find out whether your water is the problem, and a mineral formulation to stop it forming again.
The fault tree, in order
Work down the table. The first four cost nothing, and between them they resolve most cases.
| # | Check | Symptom that points here | Fix | Cost |
|---|
| 1 | Tank empty or not seated | Came on suddenly, often after a refill | Lift the tank out and re-seat it firmly | Free |
| 2 | Airlock in the intake | Pump buzzes loudly, nothing moves; follows a dry tank or transport | Run the steam or hot-water path 20-30 s, repeat 2-3 times | Free |
| 3 | Blocked intake mesh or kinked hose | Pump runs normally; recently removed the tank | Rinse the mesh, straighten and re-seat the hose | Free |
| 4 | Blocked basket, puck screen or shower screen | Water flows with no portafilter fitted | Soak and brush the basket and screen | Free to cheap |
| 5 | Limescale in the boiler and valves | Came on gradually over weeks; hard water area | Descaling cycle with acid descaler, twice if needed | A few dollars |
| 6 | Stuck over-pressure valve | Water visibly returns to the tank while the pump runs | Clean or replace the OPV | Cheap part, real work |
| 7 | Failed vibratory pump | Normal noise, no flow, after a successful purge and descale | Replace the pump | Moderate |
| 8 | Electrical: thermal fuse, switch, wiring | No pump noise at all | Diagnose or service | Varies |
How to tell an airlock from a dead pump
Listen to it. An airlocked vibratory pump is louder than normal — a hard, rattling buzz, because the piston is hammering against air with nothing to resist it. A failed pump usually sounds normal or quieter than normal, or makes no noise at all. A machine making a strained, high-pitched noise with no flow is more likely to be badly scaled than dead.
Then check the steam path. If water or steam comes out of the wand but nothing comes through the group head, you have a working pump and a blockage downstream of the boiler — which is scale in the group or solenoid, not a pump fault. That one test separates the cheap problem from the expensive one.
Machine-specific notes
Breville (Bambino, Barista Express, Barista Pro). These have a priming routine: with the tank full, hold the relevant button or run the hot-water function to pull water through. Check the tank is pushed fully home at the back — on the Barista series the tank can feel seated while sitting slightly proud. Breville also specifies its own filter cartridges, and an old cartridge can restrict flow; our Bambino review and Barista Express review cover the maintenance those machines expect.
De'Longhi (Dedica, Stilosa, Magnifica). The Dedica and Stilosa in particular are prone to airlocks after running dry, and the fix is the steam-valve purge above. Super-automatic Magnificas have an internal brew unit and more places for a blockage to hide; if the purge and a descale do not fix one, it is a service job.
Gaggia Classic and Rancilio Silvia. Both are built to be serviced, both use standard Ulka vibratory pumps, and both have a well-documented community for exactly this repair — which is a genuine part of the value of a machine built from metal rather than sealed plastic. Check the OPV before you condemn the pump.
When to stop and get it serviced
If you have purged the airlock properly, descaled twice, confirmed the tank and intake are clear, and the machine still moves no water, you are into pump or electrical territory. On a machine built to be serviced that is a reasonable repair and cheaper than replacement. On a sealed budget machine, weigh the repair against what the machine cost — and if you are replacing it, a machine with a brass boiler and available parts is the one that does not put you here again in three years.
