Post By teds01
Gaggia Classic - No Water through Group head
Hi, I recently acquired a second hand classic. I initially gave the group head a clean and it was working fine for the first couple of dozen shots. During the last shot, it seemed to choke up and water stopped pouring through the group head.
Pump seems to be working fine, when I turn on the brew and steam switch and open up the steam valve I get a good steady stream of hot water.
When the brew switch is on no water returns to the resevoir.
Is there a specific area I should focus on first before stripping down the whole thing to give it all a good clean?
I think it's possible the you have two separate problems here.
If you are getting water from the wand, this proves that water is being pumped into the boiler and that the blockage is not in the delivery to the boiler. So one of the problems must be in the output from the boiler.
All the classics I've seen have a metal tube extending from the top centre of the group head up into top of the boiler, but the hole in the bottom of the group head is offset to one side. If the small hole in the bottom is blocked, it should be easy to clear, but if it's in the top tube you will probably have to remove the boiler to get access to it.
If no water is going back into the tank, your OPV is probably seized tight and not allowing any water to bypass the boiler input, which it should be doing, especially if the output is blocked. There are numerous articles on the web on how to adjust the OPV which would probably get it working again. I have done a couple of them in situ, but one was so badly seized I found it easier to take it out of the machine so I could hold it in a vice to dismantle it.
Both problems are symptomatic of a lack of maintenance by the previous owner, and probably due to a combination of hard water and little or no decalcification.
Good luck, Deegee.
Last edited by deegee; 18th October 2013 at 09:42 AM.
I might start with the the easiest option first, the hole in the group head. I'm assuming the hole in the group head goes up and then bends, I had stuck a paper clip in there when I first cleaned the group head but it only went up maybe 4mm. I probably need to bend it around some sort of corner???
Next, I'll try the OPV. I've read about people either winding in the valve pressure adjustment (the allen key bolt) all the way in and then backing it off, this has had some sort of success. I'm just concerned about getting the pressure back to some sort of optimal setting without having access to some sort of gauge.
If fiddling with the OPV does not work, next I'll do the boiler.
How's that sound?
If the small hole in the bottom of the group head is not blocked, then the problem must be further up - probably the pipe that goes up into the top of the boiler. If you have a look at a Classic parts diagram you will see what I mean. Trying to clear the pipe through the hole in the bottom probably will not work. The hole seems to take a sharp 90° turn then probably takes another when it reaches the vertical tube.
However if it is the tube that's blocked, and it's near the top of it, you might be lucky enough to clear it by giving it a good decalcification treatment. This may also have some effect on the OPV. Has to be worth a try because the next step will be removing the boiler from the group head.
The OPV may also come good if you wind it in a couple of turns then turn it back by the same amount, or wind it out then back in again. Just moving it may free it enough to get it working again (MAYBE). If not, it's not all that difficult to unbolt it, dismantle, clean and re-install.
I have a DIY gauge and if you are in Brisbane I would be happy to loan it to you. It's a bit rough, but it does the job. Without a gauge there is a flow measuring method you can use, but it's probably a lot more fiddling around, and less accurate.
Thanks again deegee, I tackled the OPV first and wound in the hex bolt in 4 turns. Initially there was some resistance but the bolt turned easier as I wound it in. I backed it off 4 turns and then tested. Still no water through the group head.
Next, I've just pulled the boiler out, the 4 bolts holding the boiler to the group head were quite corroded. One bolt was difficult to remove. On first inspection there is alot of white corrosion (calcification??) inside the boiler and a fair bit of loose scale and grit. I'm unable to blow any air through that tube you mentioned, so therefore I'm assuming it's blocked and see what descaling liquid I have and get it to work on the tube. Will report back later.
Cheers for the guidance!
I'm in Adelaide, thanks for the offer of the gauge, might try and have one put together to do some adjustments later.
I never expected the OPV adjustment would fix the group blockage, as I thought that was a separate problem, and still do. That was just to see if you could free it up, and get some water through the return tube back to the tank, which would indicate that the OPV was working.
As to the group head, there is something I had forgotten, so I have misled you. ( Sorry about that )
In a Classic, the pipe does not go direct to the group head, it goes via the 3way solenoid valve, which is what I overlooked, and your problem may be in that valve. With the valve removed, air blown into the pipe will come out of one of the holes at the back of the group head under the brass fitting for the valve. The other hole under that fitting goes to the small hole in the bottom of the head, and if they are both clear, then your 3way valve is not working, is blocked, or is jammed in the closed position.
In my defence I must say that it has been a while since I had a Classic apart, but at the moment I have a Gaggia Carezza in pieces on the workshop bench, and it doesn't have a 3way valve, so I had that in the back of my mind while making the previous posts.
Hope this is more help than my previous attempts.
No worries. Their is no water returning to the reservoir, so does that mean the OPV is not working?
I took out the boiler, and could blow air freely through all the holes. Therefore, would that mean the three way solenoid is faulty? The spring inside the valve all seems to move nice and smooth. That makes me think it is the solenoid coil????
I'll reassemble everything this morning and test.
So far I'm assuming the following:
OPV problem as no water returning to resevoir.
Three way valve problem as no water through to group head.
How's that sound?
Thanks again for your help!
I think you're right on both counts.
If there is no water return to the tank, especially with no flow through the group, it sounds like the opv is frozen shut and will need to be dismantled and cleaned to ensure that the bits inside are moving freely. It's not a difficult job, and is easier when the valve assembly is removed from the back of the head.
If both the pipe at the top and the small hole at the bottom are clear, then the 3way valve is almost certainly where the problem lies.
I have never had one out of a machine or pulled one apart, so I'm not familiar with the internals. I do know that they are made up of two sections, the solenoid valve itself, and the coil that actuates it. They can be bought separately if only one of them needs to be replaced.
All of the above assumes that the pump is actually working and supplying a good volume of water at good pressure, but if the water from the wand is a good strong stream, with some pressure behind it, then I think we can take that as a given.
I'm now going out for the day, and will not be back online til this evening, but will check tonight or early tomorrow to see how it went.
Bugger, I gave everything a good clean and reassembled it all, but when I plug it in the wall and turn the power on at the wall the the safety switch trips. This is even without turning the actual machine on???? I'm assuming there is moisture somewhere causing this as I have checked and rechecked all the connections. I had labelled each one and took photos of each wire/plug etc!!!
Will let it sit for the day and try later on. Unless someone can suggest another solution?
If the breaker is a sensitive RCD type then moisture could be tripping it, but if it is the simpler current overload kind, the you have some other problem.
Don't want to seem too negative here, but when I have dismantled and reassembled something, and it trips a breaker or blows a fuse, I often find that it is operator error ( i.e. Me )
If it is still tripping the breaker after it's had time to dry out, you need to go back and check all the connections - very carefully.
The fact that it is tripping before you turn on any of the switches on the machine tends to indicate that the problem is in the power socket/terminals at the back of the unit or the connections from there to the switch or boiler.
It could be a fault in the switch or the boiler but under the circumstances, that is less likely.
Did you try removing the three way valve??
I had the same problem with my Gaggia (and is a common problem with a lot of Gaggias)..I removed the valve from the group head and soaked it in vinegar to clear it out...works a treat now!
there is stuff on google re removing this valve but i can't locate any atm
I've gone over the wiring, I had labelled and photographed everything. I'm pretty much 100% certain that the wiring is correct, I've gone over it a number of times. I'm thinking there is moisture somewhere that is causing the problem??? All the connections seem to look ok. I tried another power cord and it still tripped the safety switch. Would moisture in around the element/boiler cause the safety switch to trip even when the machine is not turned on but plugged in and powered on at the wall??
Also, not sure if this maybe related but the light in the power switch has never worked, wondering if there maybe a fault within the switch?
Andrew1992, I had pulled the boiler out, dismantled it by removing the group head, three way valve, OPV and soaked everything in descaler, blew compressed air through it all and reassembled. But since then I can't even power it up to see if it will pump water through the group head. Will let you know how it goes once I figure out this power problem.
Thanks for all the help and suggestions!
Just another thought, I had the boiler sitting upside down filled with descaling solution. I had not removed the thermostats so the boiler was sitting on top of the steam thermostat. When I reattached all the wiring I noticed that the black plastic part of the steam thermostat was a bit loose. I was and am able to twist the plastic part of the thermostat maybe a bit less a quarter turn to tighten it.
Could this be damaged and causing the safety switch to trip? If I disconnect the wiring to that thermostat and turn it on, would that be a way of testing?
In a word, NO. The only place that moisture could do this, is in the socket at the rear, or in the machines on/off switch.
Originally Posted by teds01
The blue active (live) wire should go straight from the socket at the back, to the machine's on/off switch. Until that switch is turned on there should be no live power anywhere else.
If it is moisture, I would suggest putting the machine out in the sun for a few hours, that should dry it out.
If that does not fix it, then I think that the fault must be in the socket (unlikely), the wiring or the switch.
If the machine is dry & the wiring is correct, a fault at the socket, or in the on/off switch are the only things I can think of that would trip the breaker with all the machine's switches turned off.
Re the light :- If the on/off light was short circuited, or earthed, it would trip the breaker, but only when the switch is turned on - not before.
Re the thermostat :- Some seem to get loose like yours did. I have seen a couple like that, but they still worked OK. I'm not sure if they screw together, or are a press fit. I didn't try to tighten them by twisting in case they are not meant to screwed. I fixed mine with a drop of super glue. But, for the same reasons as above, even if it is faulty, it should not be tripping the breaker with none of the switches on.
Now I know you took pics and labeled everything, and you triple checked them, but I'm still going to say please check one more time.
I have attached a couple of pics which show the correct connection of the most important wire - the active. It is blue, and runs from the Top terminal at the rear, to the Top Left terminal of the switch block ( looking at it from the front - top right looking from the back ).
The terminals are marked "A" and "A2" in the pics.
The third pic shows all the connections on the switch block as seen from the back. This machine was working OK yesterday after I replaced a blown thermal fuse, and I have not had any of the leads off, so it should be correct. It is also identical to my own working Classic so I'm sure that it is right. ( Mine is the one in pic 4 )
I can only suggest one simple test at this stage.
First turn the power OFF AT THE WALL AND UNPLUG THE MACHINE !!. ( Yes I know I'm nagging - but I've been zapped - it's not fun )
Remove the top spade terminal (A in Pic 1 ) from the rear socket and the brown wire below it.
Do NOT remove or unplug the yellow/green earth wires.
This will isolate the socket. Plug in & turn on the power point. If the breaker trips the socket is faulty.
If it does not trip ( and my guess is that it won't ) then socket is OK.
Turn power OFF, unplug the machine. Reconnect the terminals - blue on top brown underneath.
I started to suggest a couple of other tests, but it gets too complicated to do properly via the written word. If you can't find something from the photos, it really needs hands-on diagnosis by someone who has a circuit diagram, a multimeter and some technical experience.
Last edited by deegee; 22nd October 2013 at 02:22 PM.
It is worrying that the RCD is being tripped just by plugging the machine in.
I have attached the wiring diagram for the classic, if you cant understand it , probably best not to be messing with it and as Deegee said, get someone else who does to have a look.
Just a quick word of caution re the above circuit diagrams. The pictorial diagram shows wire colours that are incorrect on some models I have seen.
Over time Gaggia have changed the colour of some of the wires. Most of those I have seen are completely wrong by Aussie standards.
Almost opposite of what we use here, though I have got one very old one that is at least partly correct.
Agreed, I have had 3 classics and a coffee through my possession and they all were different colours!
Originally Posted by deegee
Even more of a reason to be familiar with how the electrical circuit actually works, not relying on colours of wires.
Thanks for all the replies! This is odd, the wiring at the socket was incorrect, however all my photos show the brown wire at the top and the blue at the bottom. I googled images of the internal wiring of Gaggia Classics and saw a few photos with the brown wire at the top so I looked at the wiring diagram and this confirmed that the wiring was wrong. Checked my photos and the brown is at the top???? Anyway plugged it back in, the safety switch did not trip, powered it on at the machine, the power light turned on the first time that I have seen it for a split second, then the safety switch tripped!
I've looked at the wiring diagram and the wiring looks ok, checked the wiring of my switches against your photos and all looked the same, difference is some of the colours of the wiring is different.
The only thing I'm not sure of is the wiring of the pump. Would it matter if the wires were not connected to the correct terminals on the pump?
Any thoughts on what to check next? Could it still be moisture? We have rain here today, so can't sit it out in the sun for a few days to dry!
To answer your questions :- The pump connections do not matter. It will work either way, and won't trip the breaker.
Originally Posted by teds01
It could still be moisture - can you beg, borrow, or steal a hair dryer, or better still, a heat gun ??.
As Steve said, it was worrying that the RCD tripped as soon as the machine was plugged in.
It is still worrying that it now trips as soon as it is turned on.
But my biggest worry is that the only testing we can do is change something, then see if the breaker trips, or not.
There are so many what-if's and maybe's here, and we are working from an unknown starting point.
Seems like your socket / connections were reversed before you got it, so who knows what other changes have been made.
I looked at the images on the web too. I only found one with the brown wire on top - most were blue, but it's not that important.
If they were reversed at rear of the socket, and everything else was OK, the machine should still work anyway.
The only problem I see is that there would be "live" wires and terminals throughout the machine with the switch off.
This increases the number of places where moisture could be causing earth leakage which would trip the breaker.
It's probably not what you want to hear, but if all else fails, you could try cutting all the cable ties holding the wires together, then following the pictorial circuit diagram, but ignoring the colours, physically trace every wire from end to end. The connections to the switch and the boiler must be exactly as shown. For 220/240V the elements should be in series. The wires to the solenoid should go to the two outer terminals. The wires to solenoid, the pump and the two thermostats can be connected to either terminal, as long as the right pair of wires are connected to each component.
If every single wire/connection is right, then one of the components must be faulty, but then you still have to figure out which one.
Maybe you need to start a new thread asking if there are any CS's in your area with tech ability and test equipment, & willing to have a look at it.
Unless it is fairly new, it may not be worth taking it to a pro to get it fixed. ( or shipping it to and from Brisbane )
Last edited by deegee; 23rd October 2013 at 11:46 AM.
Thanks again for your help deegee!
I'm assuming my wiring is correct and that there is moisture in the element. If I disconnect the elements and the machine does not trip the safety switch, would that indicate that the fault is only the elements? If so, I was going to pull the boiler out again and put it in the oven to dry out. I tried a blow drier for a bit, but it seemed tedious, plus it did not work.
If this does not work, I'll start another thread! Cheers!
First the answer to your question re the elements :- Yes if you disconnect the elements, and the breaker doesn't trip when you turn the machine on, then that would prove that they are the problem. Whether it is moisture in them is another question, but it is a strong possibility especially if you had a bit of overflow or liquid sloshing around while you were de-scaling the boiler.
I just re-read your previous post (#18) and my last one, and there are a couple of points I think I should make clearer.
In my earlier posts I was assuming (there's that dreaded word again!) that the wiring was correct before you dismantled the machine.
That the breaker was tripping before you turned the machine on indicates that the blue & brown wires were reversed before you got it.
After these wires were changed back, the breaker only tripped when you turned it on, & that is further proof that they were reversed.
It also reverses one of my earlier conclusions - i.e that the fault/moisture must be in the socket or the on/off switch.
Now that we know those wires were transposed, it means instead that the socket is definitely O.K.
The problem is downstream from the on/off switch now that the blue & brown wires are where they belong.
In my last post I said that if the wiring was all correct that one of the components must be faulty.
This also includes moisture in any of the components.
One of the thermostats was loose too, so moisture could have seeped into one of them too.
There is a way to progressively test each of the components sequentially - I will send you a PM about this soon.
Great, thanks for that D.G.!
Update on machine tripping safety switch. If you have pulled apart your machine and cleaned your boiler and then after reassembling your safety switch keeps tripping when powering the machine on, it is a possibility that there is moisture around your elements that is causing the problem. To test, make sure your machine is unplugged from the wall, disconnect the four wires to the boiler element. Turn on, if the Safety Switch (RCD, GFC) does not trip then it's a good chance that it is your heating elements (2 U shaped things externally on your boiler. To fix this I pulled the boiler out, took off the thermostat and steam valve, put the boiler in my oven for 1 hour at 150C.
Reassemble machine, no longer tripping the Safety Switch.
But now, my initial problem continues, no water through the group head.
How can the solenoid coil be tested?
Reassemble machine, no longer tripping the Safety Switch - - - HALLELUJAH.
But now, my initial problem continues, no water through the group head - - - Bummer
How can the solenoid coil be tested? The obvious answer is with a multimeter, but I'm pretty sure you don't have one.
However there is another way. As usual disconnect the machine first, and Be Careful !!
Disconnect the pump, & tape the terminals. Leave the top plate off and reconnect the machine.
Get a short ( 25 - 40cm ) length of plastic or DRY wooden rod - a bit of old broom handle or a wooden spoon will do.
Turn the machine on press one end of the rod to the top of the solenoid. Press the other end against your ear.
Flick the brew switch on, leave it on for a few seconds then turn it off. Repeat if necessary, listening carefully.
If the solenoid is operating you should hear a sharp click (or clack) followed by a faint humming.
If you just hear the humming, the coil is OK but the valve is stuck.
If you hear neither, the coil is probably faulty, but will need to be tested properly to be sure.
I've got a multimeter. Would that be easier, just need to know what to test for with the solenoid coil.
Disconnected the pump, taped the terminals, connected the power, placed a wooded spoon on top of solenoid, flicked the machine on (noticed a quick flash of spark from the front switch panel) turned the brew switch on and off a number of times, but no clicks or no hums. Solenoid coil dead?
OK you need to test for resistance. Pop the connectors off the terminals and test across the two outer terminals.
Originally Posted by teds01
You should get a reading that is a little over 1 K-ohm. Probably about 1.1 or 1.2 K.
It will probably be a lot lower or higher than that if it is cactus.
If your meter is auto-ranging it should be OK but if it has manual range selection, make sure it is set to K's as it may not give a reading if it is set to ohms, or to Meg-ohms.
PS It's not unusual to see a spark at the switch. You don't normally see it because the top is on and your head isn't usually in that position directly above it.
Last edited by deegee; 26th October 2013 at 03:02 PM.
No reading at all = cactus?
Originally Posted by deegee
Yes, I'm afraid that's it. It must have gone open circuit, and will have to be replaced. As I said in an earlier post, the valve & the coil come apart, and I believe I have seen them sold as separate parts, but I can't remember where. You should ask around, because the complete assembly was about $90 last time I looked.
Originally Posted by teds01
PS You could try Jaycar
Will try and source a replacement part asap. Will let you know how it goes. I wonder if having the socket wired incorrectly damaged the solenoid coil? Thanks again for all the help!
No, the reversed connections cannot be blamed for the problem. It just caused some confusion in locating it.
Originally Posted by teds01
It could be worth searching the CS site for info about a replacement. It could have been here that I read about buying the coil as a separate part for half the price of a complete valve & coil assembly.
I just remembered - site sponsor Coffeeparts has several coils listed at about $30. One of them will probably fit your Classic.
Originally Posted by teds01
Call or email them, they will know which one you need and they give great customer service and fast delivery.
I emailed them yesterday, couldn't find the exact coil on their site, so just awaiting response. Also emailed a couple of other places. I've got the coil next to me, will wander down to Jaycar this morning and see if they have something. Keen to get this machine up and running again!
Quick update, ordered the Parker ZB09 from coffeeparts.com, great service, super fast delivery. The replacement solenoid coil has done the trick! Very happy, thanks for everyones help, especially D.G.! Much appreciated!