Gaggia Classic sputters while steaming

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

#1: Post by AlwaysLearning » Jul 09, 2019, 6:49 pm

My Classic is fine when just pulling shots, purging when it should. However, when I'm steaming milk, I hear it sputtering out of the solenoid downtube as the steam is running. Seem to have adequate steam pressure but wondering if there could be more. Is this normal behavior? If not, what is the likely problem? Thanks!

tracer bullet

#2: Post by tracer bullet » Jul 09, 2019, 9:41 pm

Is it simply the above boiling temps combined with the drop in pressure, making the water go nuts and some coming out?

The times I steamed with my Gaggia I had to open the steam wand and let it go into a cup or towel for a bit until only steam comes out. 5-10 seconds perhaps, but timing of it will depend on how far you open the valve, I would have mine cracked but not full open. Until the water stopped and when it became full steam then I went full open and hit the milk.

User avatar
C-Antonio

#3: Post by C-Antonio » Jul 10, 2019, 11:28 am

there shouldnt be a connection between the boiler and that solenoid tube when the steam button is pressed, it disengages the solenoid valve.
Are you brewing first and then steaming?
If you flushed or ran water in whatever way through the group and then started steaming then the heating of the whole assembly to get to steam temperature is heating up that little bit of water leftover outside the boiler and thats what you might be seeing.

Without brewing first what happens at the brewing group without portafilter? some water there? Because the water coming out the solenoid discharge tube has to pass through the brewing group first so if the portafilter+coffee isnt there it wouldnt be able to get into the discharge tube, if its stuff from the boiler and there isnt the portafilter and everything was dry then that water would show up at the shower screen.
You can always bring to steam and then run the pump, it should push water only from the steam wand if the steam button is pressed, if it wets the group too then maybe would be worth to service the solenoid valve and make sure that the switch is ok. Disconnecting the solenoid wires at the steam button would have the same effect of pressing it, its a deviator, powers off the solenoid and powers on the heating element, so if you unplug the wires while the machine is unplugged, cover them with electrical tape for safety (internet thing), then plug in and start the machine and try steaming and the problem disappears it would point at the switch not disconnecting properly (this making sure its not the water left in the group from prior use thing). With those wires disconnected the solenoid would never work to open the path from boiler to group in first place.
“Eh sì sì sì…sembra facile (fare un buon caffè)!”

AlwaysLearning

#4: Post by AlwaysLearning » Jul 10, 2019, 3:21 pm

C-Antonio wrote:there shouldnt be a connection between the boiler and that solenoid tube when the steam button is pressed, it disengages the solenoid valve.
Are you brewing first and then steaming?
If you flushed or ran water in whatever way through the group and then started steaming then the heating of the whole assembly to get to steam temperature is heating up that little bit of water leftover outside the boiler and thats what you might be seeing.
Yep, I am and that makes sense. Just making sure it's normal behavior.

User avatar
Jake_G
Team HB

#5: Post by Jake_G » Jul 12, 2019, 6:57 am

C-Antonio wrote:Because the water coming out the solenoid discharge tube has to pass through the brewing group first so if the portafilter+coffee isnt there it wouldnt be able to get into the discharge tube, if its stuff from the boiler and there isnt the portafilter and everything was dry then that water would show up at the shower screen.
This is not entirely accurate.

The plunger in the 3 way alternates between sealing the pressure port on the group flange (fed from the standpipe in the boiler) and the discharge tube directly. The group is the 3rd "way" of the 3 way valve and is just hanging along for the ride, so to speak. The spring in the solenoid valve should press the plunger against the valve seat that is routed to the pressure port with enough gusto to create a leak-free seal unless the coil is energized, which pulls the plunger back against the seat of the discharge tube, enabling the group and PF to become pressurized.

From the symptoms, it sounds to me that the primary seal against the pressure port is compromised. Any water or steam that weeps past this seal will just fall by gravity directly out the open discharge port at the bottom of the solenoid valve. A rigorous backflush routine could clear some crud out of valve with a little luck, but the most sure fire way to resolve this is to remove the solenoid valve, disassemble it and soak all the components in some sort of appropriate cleaning solution (cafiza, pulycaff, purocaff for caked on coffee oils, vinegar or other descale agent for scale).

Cheers!

- Jake

User avatar
C-Antonio

#6: Post by C-Antonio » replying to Jake_G » Jul 12, 2019, 8:26 am


In its working position in Gaggias the discharge tube connects from the top of the solenoid, passage from boiler to group is at the bottom.

The bottom assembly has a nipple where the plunger gasket can seal against and another hole flush with the bottom of the solenoid valve "chamber" (for a lack of better words, I dont know what would be the name for that space in english) beside the nipple, not sealed.
The group is always open, the solenoid either locks out the boiler or the discharge tube but not the group (as you said too). Because of that and the position of the passage any leak would always end coming out the shower screen at the group first, its the lower passage to the group which always get wet, the water always goes there first. Again, the discharge is at the top where the barb connects a rubber tube that curves back down to the metal tube visible in front of the tank. Water wont come out of there unless the bottom open channel to the group was occupied first.
If OP brewed and has the portafilter on with spent coffee grounds when steaming etc then that passage would be less able to drain and if there was a leak would occupy that room first and only then come out the top discharge. On the other hand, if theres no leak and the portafilter is on, OP would also not notice the bubbling of the leftover water at the screen caused by the whole thing heating up for steam and hear it only at the discharge (you would see that at both usually). For that reason I asked what was the situation with the portafilter off.

When you switch on and off the steam diverter button you not only turn on/off the heating elements but also engage and disengage the solenoid (steam on = no power to solenoid and viceversa), so when you want to get hot water pumped out only at the steam wand you turn the steam on which disengages the solenoid locking shut the boiler (meaning the steam valve is the only exit for the boiler water).
Now, the behavior on a setup with no problems is that with everything dry, steam button pressed, steam valve closed, and pump button on, the water has nowhere to go, cant come out the solenoid side because that is kept shut as its disengaged, and cant come out the steam valve because we are keeping that closed also. Pump tries to push water but everything should stay dry (eventually the OPV would take over depending on where its limit is set).
For this reason I also wrote to check that.
If the solenoid valve wasnt sealing well and he did that operation he would see the water from the leak and he would see it at the screen first, not at the discharge tube.

If OP reverses the routine and steams first and brews after, at the first use of the machine, the whole solenoid discharge tube and group should be dry and his problem should not show up if its heat and leftover water causing it, I would suppose OP checked all the options at this point.

In any case, things should be always cleaned and maintained and a dirty-ish solenoid valve is always possible even backflushing and the gaskets are not eternal, it never hurts to take things apart, visually check and clean them periodically (and for a quick thing: switching continuously the steam button would engage/disengage the solenoid rocking up and down the plunger, that often can move away some crud temporarily solving a problem).

(btw: even my Gaggias all do the same thing OP one does, even one that is brand new... none of them has leaks)
“Eh sì sì sì…sembra facile (fare un buon caffè)!”

User avatar
Jake_G
Team HB

#7: Post by Jake_G » Jul 12, 2019, 12:24 pm

C-Antonio wrote: In its working position in Gaggias the discharge tube connects from the top of the solenoid, passage from boiler to group is at the bottom.
Of course, you are correct! :oops:

Too early for me to be posting!

Even so, I do believe that it is likely that steamy sputtering and such could make it out the discharge tube without so much "passing through" the group. It just would need to fill the body of the valve. It should weep through the group, yes, but I would say that all fluid that exits the discharge side had to originate from the group.also, the Gaggias I've been in didn't exactly encourage free flow through the passage from the solenoid to the shower screen until I was done with them.

After reading the rest of your reply, I am beginning to better understand your answer. Basically, post brewing, the solenoid chamber is flooded and water is help in place by the fact that the shower screen is "sealed" by the portafilter and spent puck. Upon switching to steam, the water in this space boils and gurgles out the tube. This makes perfect sense, but it's not something I've encountered first hand, which is odd. Maybe I just never noticed it?

Anyways, thanks for your excellent posts. I appreciate reading then all.

Cheers!

- Jake

User avatar
C-Antonio

#8: Post by C-Antonio » Jul 12, 2019, 1:36 pm

Jake_G wrote: After reading the rest of your reply, I am beginning to better understand your answer. Basically, post brewing, the solenoid chamber is flooded and water is help in place by the fact that the shower screen is "sealed" by the portafilter and spent puck. Upon switching to steam, the water in this space boils and gurgles out the tube. This makes perfect sense, but it's not something I've encountered first hand, which is odd. Maybe I just never noticed it?
The fact is that when the machine opens the 3way after brewing the discharge of pressure develops a flow fast enough to suck away quite a bit of moisture at the whole screen assembly together with the puck. So doing normal shots you might not have noticed it happening but if you were to play with the shot pressure opening the steam valve to simulate a dropping pressure and maybe go a bit too far, you are gonna end with less pressure in the portafilter at the end of the shot, less "suction" of the pressure discharging, a somewhat wetter puck and more moisture at the showerhead assembly. (you probably noticed that gushers also leave a wetter puck)
If you want to really exaggerate the whole thing you can turn on the machine letting go to temperature then lock the portafilter with an empty filter and flush it (like you would do if you were in a rush and were trying to warm up everything quickly). That way cant hold much pressure in the portafilter, the discharge tube can get wet but the shower screen assembly remains soaked, remove the portafilter and flip to steam, that water boils off fast and it looks almost like the whole thing is leaking for a second.
If you bring it to temperature and flush without the portafilter and then go to steam its mostly the shower screen boiling off because the discharge side is dry or barely wet.
Im sure that you wouldnt have much difficulties reproducing the whole thing, the hotter the system and more water is there to boil off suddenly instead of having the time to calmly drying up the more you see it... might be the routine OP uses that leads to it more often that usual.
Im travelling right now (more delayed than moving) otherwise I would get a video of it.

PS: I dont know how much the gurgling that OP hear is, he said sputtering which makes me think minimal and what I already saw on other Gaggias but if its an actual gurgling, kettle like, then yes he might have a leak. Without the machine in hand cant really exclude anything so who knows. In these threads it becomes a weird ping-pong of "try this""try that" to find some more leads and I always hope for folloups and an OP conclusion of the story to see what it actually was but most of the times we are left with the curiosity.
“Eh sì sì sì…sembra facile (fare un buon caffè)!”

tracer bullet

#9: Post by tracer bullet » Jul 13, 2019, 8:52 pm

Now that I re-read the first post I see OP's mention of the solenoid downtube. I had the steam wand in mind when I was trying to say it's rather normal to see a little water come out. Oops. Now I understand why the last few posts were written - wondered why on earth we were going down that path.