good morning YouTube we're looking at the back  side of my Breville barista express coffee machine  

this is where the tank sits and I've already got  that loosened up here so I've had to open this  

machine up again I'm thinking I have a problem  with low pressure out of the pump and I also  

have a problem up above here on the hot water and  steam valve on the side there so before I get into  

the repairs I've been looking around inside here  both inside the machine and then I've also looked  

at the part diagrams on the replacement parts web  site the diagrams themselves aren't that useful  

from what I found but the parts descriptions and  photos are actually somewhat informative but I  

think I've figured out how the water flows through  this machine in the various modes and I figured I  

would take a look at that this is the hose that  comes out of that valve that's on the tank there  

so the water comes in here I believe that's a  check valve at the bottom there and then this  

round device here with the three wires plugged  in a flow meter so I believe this probably has  

power ground and a signal your typical three  wire sensor and this device here measures how  

much water is flowing in from the tank and then  out to the bottom of the pump that's right here  

and I imagine what they use that for is number  one for the one cup or two cup brewing cycle so  

when you program in the size of a one cup shot  it knows how much water to send through there  

and then I think they probably also use this  for the clean me light there's likely a little  

vein inside of this that spins as the water flows  through and it probably puts out some pulses that  

go out over this wire and then into the processor  board that's behind here so they probably use that  

for the clean me light as well so many pulses of  the meter turned the clean me light on this hose  

goes out here's your pump the inlet of the pump  is down there on the bottom then the pump comes  

up here this is the output of the pump and then  right here this is what they call their safety  

valve or overpressure valve so it's kind of like  a tea fitting it's open up this way so the water  

normally just flows up and out but if the pressure  exceeds probably around 15 bar it will come out  

this way and then dump into this tank over here or  what they call the diffuser so before when I first  

looked at that I thought this was on the inlet  side but this is actually where they dump excess  

water and aim and pressure and you can see this  this thing is sort of shaped like a car muffler  

inside there's all these baffles and I guess you  get some of the coffee residue that gets down in  

there as well if the pressure is exceeded that  goes right in here so this hose on the far end  

comes out of the solenoid block and dumps in there  and then this Center hose comes off of the manual  

hot water and steam valve and that's the overflow  or the the exhaust port on this valve they call  

this the diffuser so this basically dissipates the  high pressure and then right underneath here my  

finger is just on the little rubber pipe that  comes out of the bottom of this diffuser into  

your drip tray that's where your excess hot water  and steam comes out of the diffusers and so every  

time you finish a brewing cycle or especially if  you run the hot water or steam and you turn this  

from hot water back to standby you'll hear a big  woosh and that's the water and steam coming into  

this diffuser and then you'll see steam coming  up out of the grilles on your drip tray so that's  

how that works so that's the overpressure side  of things so like I say here's the normal flow  

comes up out of the pump up through this hose  and it comes in to the top of what's called the  

thermal coil so inside of this thermal coil is  coiled up tubing if we look on the top here it  

says 120 volt 1600 watts so this is 1600 watt one  point six kilowatt heater and of course if you're  

outside the US you'll have a 240 volt heater  and you'll have 240 volt solenoids and a 240  

volt pump so the pump only pumps cold water so it  comes in cold goes up here into the coil probably  

makes a number of loops and then it comes out  over here so this hose here comes out of the  

bottom of the thermal coil and into this elbow  that goes into the solenoid block here so this  

is what they call the 2/3 way and I guess what  that means is that there's three ports you've  

got one port on that side you've got a port  on that side and then you've got a port on top  

so there's three ports and then it's a two-way  valve so if this solenoid is off the hot water  

comes out of the coil and comes up through here  and that goes over to your hot water steam valve  

here this right here is your hot water outlet in  fact if I put my finger down there just underneath  

that's where the hot water comes out and that's  right below this tube and then the steam wand  

comes out right down below here's this tube is the  diffuser or the dump lines so on this valve when  

you switch from hot water or steam back to standby  it dumps all the pressure out of this tube right  

here and then I guess the way this valve works  it's a mechanical valve so there's no solenoid  

involved but you can see there's a little limit  switch there and there's one down there yeah a  

couple of wires up there off the top that run down  there and they probably go back into the control  

board here those switches tell you there is steam  if that switch is closed and then when it's steam  

mode it tells the thermal coil to heat up a little  bit hotter to superheat the water and then in the  

water comes out here and then flashes to steam in  your steam wand and then when you release it the  

pressure gets released down into the diffuser and  then out into the drip tray and likewise if you're  

in hot water mode this bottom switch closes right  there and then it's water up through this one and  

out your hot water so anyway that is the hot water  steam side now if this solenoid is turned on this  

upper port blocks but the lower port passes water  through and then it comes out of this line and  

this line I thought went into the thermal coil but  it actually goes into the group head down here so  

this is where your espresso water gets pumped  and it goes in here and then down through the  

filter basket and into your cup and then about the  only other thing you've got up here here's your  

pressure gage so there's a hose that comes off of  the top of the group head and then over and down  

to the gage what's the back of the gage that that  hose plugs into to brew your espresso you turn on  

the pump you turn this solenoid on the water comes  up here heats the water it comes out here it goes  

through the base of this valve it comes up here  and and runs down into your culture basket and  

comes out the bottom and then when the brewing  cycle stops this solenoid turns on and lets any  

excess pressure go out here and drain down into  the diffuser again so this is critter drain valve  

and then this one is switching between hot water  steam and espresso yeah so now it finally makes  

sense why if this valve was buzzing which is  why I replaced it it wasn't able to fully turn  

on so it left both sides open so this side here  was open to the group head but it hadn't closed  

this hose so the flow was splitting between this  hose and this hose and what happens is if your  

hot water and steam valve is in the standby  position this incoming hose feeds directly  

into the exhaust hose so what it was doing was  bleeding awful some or all of the pressure out  

of the pump was getting sucked through here and  then down through there because this valve here  

wasn't fully closing off the top pork so that's  why this valve is really critical because as I  

showed you in the previous video this valve has a  some metallic slug inside when it's down it plugs  

the bottom port within when it's up on the top it  plugs this top port which stops water from going  

up here but if this valve is buzzing or it can't  quite move fully then it's trying to send water  

here which needs a lot of pressure or send water  here that just comes straight down the drain so  

actually in my case this valve was probably okay  but it was this valve that was causing problem but  

yeah anyway I think that's how this works but I  want to actually see for sure if that makes sense  

that picked up a couple of these hundred 20 volt  indicator lights and I'll hook these indicator  

lights up in parallel with the solenoid so if  the solenoid turns on the indicator light turns  

on and I'm gonna put these in the cover towards  the back and I'm just gonna leave them in there  

and then I'll be able to see if this light turns  on that solenoid is on and if that light is on  

this solenoid is on and I'll be able to see how  those solenoids work and having some blinking  

lights on there's good things so anyway that's one  of my future projects so stay tuned to one of the  

next videos and I'll show you putting these in and  we'll see if my hypothesis on how these solenoids  

work is correct the next project I have is I think  might pump or the safety valve might be defective  

because I've been noticing my pump output or the  pressure output on the gauge has been falling and  

it's almost non-existent now so either the pump  is bad and the pump is actually rebuildable but  

I figure I would just change the pump out so I  picked up a new pump and a new safety valve so  

I want to just put that in right away and then  I'll take this one out and we'll try testing  

the pump and I'll see if I can figure out some way  to test the valve and then you might have noticed  

that hose that's another project because I saw  some signs of water dripping you can see there's  

a lot of white calcium or limescale built up here  and like down here there's some and so there was  

signs of water leaking out of this manual valve  I literally just touched this hose and it was  

loose and that was inside of there that was the  original hose barb that used to be part of that  

casting right there and it was stuck inside of  the end of the hose so I got that out of there  

you can see how corroded it is I don't it was a  defect in the casting because the outer wall is  

just paper-thin and there's like nothing inside of  there but anyway I need to fix that because that's  

just a direct water leak if there's any pressure  in this line it goes up here and right out there  

and this drips down inside the machine we've got  to repair that we've got to replace the pump and  

then when I'm putting it back together I'll put  some blinking lights in there got a couple of  

projects lined up so anyway I hope you enjoyed  that look inside of one of these machines do  

you have any other questions post up in the  comment section below you like content like  

this subscribe to the channel link in the lower  right corner and as always thanks for watching