Breville BES920 no pressure or water from group head

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by TreeV »

Hello all,
I've been unable to find the same issue I am having with my used Breville BES920. OPV was replaced, it has the newer type o rings, and the pump is also new, and water comes from steam and spigot fine. Heat is good, but no pressure registers and no water comes from group head. I've checked the lines for blockage and they seem fine. O rings all look good. Im just not sue what to check next. Any and all help is much appreciated. Thanks in advance!

Give me the crema

#2: Post by Give me the crema »

There are 2 pumps.
Pull the line from the main pump and activate the group head. If no water comes out and it's just vibrating away you need a pump.


#3: Post by WWWired »

Hi TreeV . . . sounds like you're well on the way to a fully restored and maintained incredible espresso machine! The BES900/920XL series dual boilers are absolutely brilliant and when maintained properly can go on and on and on.

Always worth reviewing a BES920XL's fault/error logs, ←click-here-for-how :) Post if you find anything (even pictures of your fault/error listing if something shows up) ;)

A few questions too:
(1) Do you hear the pump being energized (vibrating) when you make a call for water at the GroupHead?
(2) Do you have any pictures of your OPV installation?
(3) How many extraction cycles is showing on your Log? (if its 500, multiply by 10 and that means over 5000
and that's usually time to begin considering pump replacement.

As you opened and replaced components in your Brew/Grouphead hydraulic pathway (completely separate from your Steam hydraulic pathway), it may be worth considering if you possibly have an air blockage in the heat-exchange portion (see annotated dual boiler schematic below) of the pump-to-Brew-Boiler line that leaves your
. . . . . . brew pump --> OPV --> Loops through larger steam boiler --> travels into Brew Boiler
You may need to make a call for water from your GroupHead before the machine heats up, so immediately as soon as it is turned on after being fully cooled down. This will move any air in the line through before it has a chance to heat up inside the Brew/Group Hydraulic pathway.

Report back what you are seeing in your logs . . . note that you may need to reset your BES920 Logs if they are maxed out at 99 for any of the Fault Logs so you can see anything new that's developed since you replaced your OPV.

Listen for your Brew Pump at all times when you are making a call for water from the Brew/Group hydraulic system (again, completely separate from the Steam hydraulic pathway). Let us know what you hear and even post a video here of your attempts if possible as everyone loves pictures and videos :) If you are not hearing any noise from your Brew/OPV/Grouphead pump (completely separate from the Steam pathway pump), the problem could be
(1) A wiring/connection issue (as you were working in the Brew Pump area to replace the OPV)
(2) The diode in the pump is experiencing a fault
(3) The Coil in the pump is experience a fault
(4) The Thermal Cutoff on the Pump is experiencing a fault (see photo of view from back of machine below)

Note that these pumps have a duty cycle of usually around approximately 1 minute on and 1 minute needed to be off (1/1 listed on pump). If you run the pump for longer than one minute too many times, it will usually begin to experience wear. There is a safety feature on Breville Dual Boilers that should shut the pump off at 90 seconds I believe. If this happens, you'll need to completely shut the machine off and unplug it for a few minutes to reset it I think? (someone can probably confirm). That would result in no water of course as well. You can actually see the second pump (the Steam Boiler hydraulic pathway pump) just to the right and a little lower with its thermal cut-off fuse as well. The white plastic thing being held out of the way is the back of the brain box/control board for the BES900/920 models . . . there are two or three screws that hold it in place.

. . . and here's a bit of a diagram (credit to Breville for main schematic) showing possible air-lock location in an BES900/920XL hydraulic pathway that has been either open to the atmosphere by replacing parts in the pathway or by a leaking o-ring (note also it is not uncommon for o-rings to need to be checked after replacement as they can continue to allow penetration of the atmosphere and that will lead to air-locks as well as it will throw off the water levels in the smaller brew boiler and also allow water to boil at a lower temperature/pressure of the atmosphere exposed through leaky o-rings) . . .
if your pump is energizing (and you can hear it, an air-lock due to a leak could be one issue as well, again listen for pump being activated).

There are other possible block locations, for example the solenoid not opening but that's for later consideration. Check the above first perhaps

TreeV (original poster)

#4: Post by TreeV (original poster) »

Thank you so much for all the information! It is so very helpful. I believe my problem is with the overflow valve. The pump is working, but water is going back into the reservoir when called for at the brew head. The shot count is 210, so not too terribly high. Error codes show coffee water flow failure so that fits with what I am seeing. I've only been able to find a replacement in Australia so have sent off for the replacement. Probably will be a couple of weeks before I will know for sure, but I will be back on for more information if this doesn't work. Thanks again for all the input!
Great group of people here!


#5: Post by WWWired »

There are two flow meters in the BES900/920 models . . . one before the Brew Pump and one after the OPV (which is mounted on top of the Brew pump assembly). The Two flow meters measure the amounts of fluid passing them and compare the values. If the fluid amount flowing past the OPV associated flow meter is less than the fluid value amount in the flow meter entering the pump, an error will register.

If you have a blockage in your Brew Boiler/Grouphead hydraulic pathway, this could cause a functioning and good Brew pump (separate from the Steam hydraulic system pump and lines) to build pressure to the OPV (which again is sitting atop the Brew Pump assembly) to the 9 or so Bar of target pressure at which point it would shunt the water back to the reservoir.

A non-functioning 3-way solenoid (mounted on the rear-top of the Brew Grouphead Assembly (just posterior of the smaller Brew Boiler), that is not opening might be the cause of water not being able to flow through the Brew Boiler and Grouphead hydraulic System as well. A failed OPV ("overflow") valve could also be involved as you suggest. These can be removed and disassembled and inspected, looking for a failed spring, mineral build up, debris or other obstructions. Be sure as always when removing these components that the machine is unplugged and never reach inside the case of a machine when it is plugged in for sure :)

The question is: Where is the block occurring. As pressure in a fixed volume pressure vessel is the same at every point (when water is involved), this could mean:
  1. That the OPV ("overflow") valve is stuck in the overflow-to-reservoir position for some reason or even that the flow meter itself (the one after the "overflow/OPV") is blocked/seized/mineral-scaled;
  2. That the 3-way solenoid mounted on the back of the Brew Grouphead assembly is experiencing a fault of some type (failure of the coil, or plunger assembly); or
  3. As mentioned in a post above, a vapor/steam lock in the Brew Hygdraulic Pathway, from the Steam Boiler to the Brew Boiler section, could stop water flowing as well (see picture above of where and how this can occur).
The idea that pressure "is be equal at all points" in a fixed volume system, like the Brew hydraulic pathway of a BES900/920XL, means that the 9 bar build up pressure could occur at any point in the Brew Hydraulic Pathway . . . the "overflow" valve (OPV), the flow meter after the "overflow" valve, the 3-way solenoid mounted on the back of the Grouphead Assembly or in one of the high pressure water lines. The great thing is you will soon be an expert in every part and component of these machines (and many others that share dual boiler engineering) :) Many people who develop expertise as they go like this will often be able to very quickly tell how their machines are functioning just by the sounds it makes alone or when a Fault Code is found in an error log etc.

Definitely your error code suggesting "water flow failure" is a great observation and shows how fantastic the fault codes can be for assisting in narrowing faults. I'll send you a PM about an OPV ("overflow") valve as well. Here, the "water flow failure" likely indicates the two flow meters, before the Brew Pump and after the "overflow" (OPV) are not recording equal amounts of spin on the sensors in each as water flows past the second one. Since water is flowing back into your reservoir, that should indicate your Brew Pump is functioning well and for 210 x 10 extractions (2100) that is less than half of the reasonably expected 5000 life on a Brew Pump were replacement could begin to be considered as needed.


#6: Post by imrolly »

Hi WWWired,

I have a question for you and the group. My wife made an Espresso a couple weks ago and she heard an smal *POUF!* with white smoke. When took a look inside, I found a melted pump (attached picture). I did the replacment with a new pump but the pump doen't start. Before I go foward with all the test(OPV and more) it's possible that I'll need to replace the termal cut off switch ?

P.S. I only have a fault on 8:06
Thank you for your support


#7: Post by WWWired »

imrolly wrote:Hi WWWired,

I have a question for you and the group. My wife made an Espresso a couple weks ago and she heard an smal *POUF!* with white smoke. When took a look inside, I found a melted pump (attached picture). I did the replacment with a new pump but the pump doen't start. Before I go foward with all the test(OPV and more) it's possible that I'll need to replace the termal cut off switch ?

P.S. I only have a fault on 8:06
Thank you for your support
Hi imrolly :) Apologies for the delay in replying, as was on the Virus Rides at the Sick Circus!

Woof! Fried that diode but good! . . . and yep, possibly cooked your Thermal CutOff Fuse too. If your Thermal Cutoff fuse is permanently opened and no continuity is possible, the circuit powering the pump will not be energized. Your 8:06 fault log record wouldn't be too unexpected with the pump failure so not too concerning just yet. The Coffee Flow Error has to do with the two flow meter measurements (one before and one after the pump), and comparisons of those values.

A good first step would be to test your Thermal Cutoff Fuse circuit (by probing the two crimped ends of the yellow wires as seen in the photo above) for continuity using a Digital Multimeter (if you have or can borrow one) set to Continuity. If there's no Continuity, it's possible to bypass the thermal cutoff fuse (with the machine unplugged please) by just clipping off the bad fuse (leaving as much wire as possible still attached) and twisting the two wires together temporarily (be sure the machine is unplugged when doing this and only do it for testing purposes briefly). If your pump and machine starts, all great, proceed with getting a new thermal cutoff fuse and installing. Again, be very sure never to reach inside a plugged-in machine please :)