# Intermittent Classic water flow problem



## 00bins (Aug 21, 2016)

Hi all

I've had my Gaggia Classic for about 10 years. It is used at least once per day, often much more than that at weekends.

It's been descaled (although not regularly) and has pretty much been faultless all of this time.

I've cleaned the 3-way valve before, and I've done that again and still no joy.

I've also made a blind pressure gauge thingy and reduce the opv to around 9 - 10 bar

Recently however it has started fail to produce any water through the group head or the steam wand - only steam.

Also, the sound from the pump would change from the normal noisy clatter to kind of muted hum, a bit like the sound it would make when doing a back flush. I've never done a back flush with any detergent btw.

Sometimes I could 'fix' it by running it without the reservoir of water (I know that's probably not a good idea) but i could get the pump to 'sound' ok again and then it would work properly after I'd primed it by running water through the steam wand.

Anyway this usually happened after the machine had been on for while, so I suspected that it was related to something overheating,- so after much Googling I decided to replace the brew thermostat. This didn't really fix the problem and I'm back where I started.

What's odd is that it's been on since before I started typing this and it's still working - in some ways this is worse - not knowing if it's going to make a coffee in the morning.

So even though it's currently working I'm posting this just to see if anyone can help diagnose the problem

Thanks

Rob


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## GCGlasgow (Jul 27, 2014)

May be solenoid valve, it needs taken apart and cleaned thoroughly, sometimes 2 or 3 times.


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## 00bins (Aug 21, 2016)

GCGlasgow said:


> May be solenoid valve, it needs taken apart and cleaned thoroughly, sometimes 2 or 3 times.


Hi

I did that yesterday. When you say 2 or 3 times do you mean clean it, replace it, run the machine then repeat?

Thanks


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## GCGlasgow (Jul 27, 2014)

yes sometimes they can get clogged up again.


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## El carajillo (Mar 16, 2013)

Any loose or damaged connections or any showing signs of scorching/ burning-- pump , solenoid, stats ? High resistance ?


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## gaggiamanualservice.com (Dec 22, 2009)

If working when cold and failing when hot it will be solenoid faulty. Had a few that only show fault when heated up.


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## 00bins (Aug 21, 2016)

Is that the solenoid or the 3-valve? Could it be failing intermittently - I've left it on for ages today and it's been fine.

Thanks

Rob


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## timmyjj21 (May 10, 2015)

You mentioned that it would fail to produce water through the group head AND steam wand? And it would be fixed by running the pump dry?

I would normally be saying your issue is the solenoid, but the above info doesn't fit- water should still come out the steam wand if it is a solenoid issue.

It could be one of the internal valves of the pump getting jammed, but this usually makes an amazingly bad rattle noise... Can you confirm the water flow, as this is important for diagnostics.

In the meantime...have a read of this and see if you would find it fun!

http://ulkapumprepair.blogspot.gr/2008/10/original-website-page.html?m=1


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## 00bins (Aug 21, 2016)

I have heard (and only recently) a really bad rattling noise - it was so bad I remarked to my S.O. that it had never made _that_ noise before. It's only done a couple of times I think.

So to recap - no water from _any_ orifice, only steam - including the group head - which is why I thought replacing the brew stat would fix it. It looked like the boiler was so hot that the water that should come through the head was steam ... if that makes sense

Thanks

Rob


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## timmyjj21 (May 10, 2015)

Ah, righto! So it presents as an overheating problem, with steam coming out the brewhead instead of water. Sorry, when someone mentions "no water" we all start thinking solenoid, but I think you have something different in this case.

Possible causes I can think of, none of which I am convinced are likely:

The brew thermostat was replaced with a steam thermostat? They look the same, but have different temperature settings.

Brew and steam thermostat wires mixed up? Difficult to get it wrong due to positioning...

Finally an incorrectly wired steam switch, causing it to be set to steam all the time?

I'm a little stumped...


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## 00bins (Aug 21, 2016)

>> The brew thermostat was replaced with a steam thermostat? They look the same, but have different temperature settings.

This is possible - I did order a brew stat but didn't check the rating/part number when I fitted it. I'll do this when I get the time later. I suppose that if the original brew stat _had_ failed and I then replaced it with a steam one the symptoms would be more or less the same

>> Brew and steam thermostat wires mixed up? Difficult to get it wrong due to positioning...

>> Finally an incorrectly wired steam switch, causing it to be set to steam all the time?

definitely neither of these (unless someone broke in and rewired my coffee machine









Thanks for the help

Rob


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## 00bins (Aug 21, 2016)

I haven't got around to checking the brew stat, but I do have another piece of info ...

it's usually after the first cup I've made that I get the problem. I've left it on for ages (eg after the last time I cleaned the 3-way) and on other occasions, and it make a decent cup, then goes wrong. It's usually more apparent on weekday mornings where I have timer turn it on at 6.30, make a cup around 6.50 and turn it off. Later when my partner gets up and tries to make a cup (or at the weekend if I just try and make one straightaway ) it goes wrong - muffled noise from the pump, no water...

does this ring anyone's bell?

cheers

Rob


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## Jumbo Ratty (Jan 12, 2015)

People have told you it's your solenoid already ; I'll add my voice to that.

You say you've not descaled it as much as you should.That being the case you can take the solenoid off, clean it out with a pin and remove the scale thats blocking it, put it back on and in a cup or two block again. This is because you have loose fragments of scale in the boiler.

Sometimes these pieces of detritus can block then unblock, then block again on their own accord.

This leads to frustration of the user and an uncertainty that the problem is more sinister

The mufffled sound, thats because the solenoids blocked

Its your solenoid. Pound to a pinch of shit its your solenoid


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## timmyjj21 (May 10, 2015)

Yep, your symptoms are most likely the solenoid. Forget the whole heat up/ warm/ second coffee/ intermittent part. It's most likely the solenoid partially blocked with scale that shifts around. I'm unsure of where the steam production issue comes from, but when cleaning the solenoid you can check the new thermostat is correct.


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## 00bins (Aug 21, 2016)

Thanks for the replies.

Can I just ask you (all) when you say "It's your solenoid"

Do you mean the actual solenoid (the electrical device that controls the 3-way valve), or the 3-way valve. I can clean the latter but only purchase the former

cheers

Rob


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## Jumbo Ratty (Jan 12, 2015)

its the metal part,, the solenoid needs to be removed and then dismantled,, then get a pin just a slightly bit smaller than the top hole and rummage around in there.

see the brass piece, the round top part where the spring has come from, that top hole in the center, get the pin in there. that hole corresponds with the hole on the right (with the little rubber seal on) Cover the left hole and fill the top round part with water and blow the water through into your hand (this is after the pin treatment), it will be hard to do this. Feel the water when it comes out, , you might feel the scale.


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## 00bins (Aug 21, 2016)

Right then - I'll be dismantling this chap again soon (no time right now) and shall report back as and when.

Thanks everyone

Rob


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## 00bins (Aug 21, 2016)

Hi all

Last saturday I did the job on the solenoid valve, and afterwards it seemed to be ok.

I didn't double check the brew stat but I left it on for ages (hours) so that it was properly warmed up and it worked fine. I didn't actually make any more coffees because I'd already had enough by that time...

The next day it was back to its old ways.

It seemed especially to be ok on the first cup but would get bunged up on the second. I've uploaded some vids

that show what happens, and that it can be 'fixed' (sometimes) by running it with no water.

stuck - no water






So if it really is the solenoid valve, and I have to clean it every other day to get a coffee, what else can I do? It's impractical to do that so is there a more complete process to cleaning everything to remove scale (the boiler, the pump?)

Is my grind too fine perhaps? Am I tamping too hard?

I really want to keep it, and am reasonably competent taking things apart and putting them back together so am open to any more suggestions.

thanks

Rob


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## Jumbo Ratty (Jan 12, 2015)

its because the loose scale in your boiler re clogs the solenoid.

You need to descale the machine much more regularly than you are doing.

My solenoid used to block all the time, , i could take it off, clean it, put it back on and it work fine for a few cups then block again,, very annoying.

I thought i was descaling regularly enough but I wasnt.

i now descale once a month regularly,, havent had the problem since


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## 00bins (Aug 21, 2016)

Jumbo Ratty said:


> its because the loose scale in your boiler re clogs the solenoid.
> 
> You need to descale the machine much more regularly than you are doing.
> 
> ...


Ok so will descaling now be sufficient in your opinion to get rid of all the bits that are in there? or should I clean the whole thing (as per this http://protofusion.org/wordpress/2012/04/gaggia-classic-disassembly-and-cleaning for example)?

thanks again!

Rob


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## Jumbo Ratty (Jan 12, 2015)

00bins said:


> Ok so will descaling now be sufficient in your opinion to get rid of all the bits that are in there? or should I clean the whole thing (as per this http://protofusion.org/wordpress/2012/04/gaggia-classic-disassembly-and-cleaning for example)?
> 
> thanks again!
> 
> Rob


The example above would be a very thorough way of doing it. And then going forward set up a plan of how often you descale,. How often would depend on the water you use and how much use the machine gets.

For example my water is filtered via an inline filter running to a tap on my sink. I make 5 cups of coffee per day approx. I descale every 1st day of the month.

I now have absolutely no trouble with my solenoid blocking.

Giving it a descale now may dissolve the scale in the boiler and that may solve the problem, but I reckon your boiler is quite heavily scaled and a descale would result in flakes of the scale blocking the solenoid again and again

I didnt take my boiler apart, i just descaled it and kept taking the solenoid off and back on until all the loose scale had come out. Yes, I took my solenoid off perhaps twice a day for a while to do this. It was very frustrating. But I learned from this. I thought my filter was sufficiently removing whatever causes scale to build up and didnt descale often enough.I was wrong.


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## 00bins (Aug 21, 2016)

I took the plunge and dismantled the boiler and soaked it overnight in citric acid. It was quite grim (some pics here - http://imgur.com/UIBEDIw, and here


http://imgur.com/p8khZhF

)

Today I put it all back together and the boiler is leaking. I suppose I should have replaced the gasket but didn't.

The gasket it sits in a groove and is kind of flush with that groove - I would expect it to sit a bit proud - is that the sign of a gasket that needs replacing.

The boiler was quite pitted inside and around the base so I cleaned it with a dremel wire brush - is there a chance I could have caused that leak myself?

I'll order a replacement anyway - has to be worth a try before getting a new boiler, although the amount of pitting and corrosion in the boiler doesn't fill me with joy...

thanks for all your help - onwards and upwards..

Rob


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## jimbojohn55 (Jan 15, 2016)

more power to your elbow - defo just try a new gasket first - and be prepared to flush several litres through it before the metallic taste goes !

have a think about testing the thermostats on an older machine - there often out by several degrees - or just order a couple and add it to the rebuild.


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## 00bins (Aug 21, 2016)

The old gasket looks quite flat. Do new ones have a circular cross-section?

And how do I test a thermostat?

Thanks

Rob


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## jimbojohn55 (Jan 15, 2016)

copied from coffee crew link in the gaggia section of the forum-

The Gaggia Classic has two thermostats - a brewing thermostat and a steam thermostat.

You want to test two things:

1. brewing water temperature and recovery

2. steaming capability

The most well known and simplest brewing temperature test is the "styrofoam cup test"

Turn on your machine and wait at least 15 -20 minutes so that it is thoroughly warmed up.

Get a small styrofoam cup of the take-out variety and mark a line measuring the 2 ounce level, and another mark measuring the 3 ounce level. In metric terms that's roughly 60 ml and 90 ml respectively. Next, you will need to find a good quality dial type frothing thermometer and insert it horizontally through the cup. The point of the thermometer should not puncture the other side and the thermometer should be inserted low enough in the cup that the stem is covered by water. Place the cup along with the thermometer underneath your group and turn ON the brew switch and draw at least two ounces of water. Turn OFF the brew switch when you have enough water in the cup. Measure the maximum temperature achieved.

Repeat this test several times in a row using the 2 ounce mark. Do the test again using the 3 ounce mark.

If you are not attaining at least 192F (89C) in all tests, then your thermostat is running too cool. I would be tempted to either return the machine or replace the thermostat.

The next test measures the steaming capabilities of your new machine.

Measure out exactly 10 ounces of water in your frothing pitcher. Insert your frothing thermometer. Remove any frothing assist devices as you will need to use the bare wand. Click on the steam switch and wait for the red "ready light" to come on.

Start steaming by opening up the black steam knob. You will notice the red light will go off after a short time indicating that the boiler heating elements are on and are actively heating the water. Keep steaming until the temperature light comes back on. Record the temperature. If it is not at least 140F (60C), your steam thermostat is running too cool and should be replaced. The steam thermostat is very easy to replace and if you can wield a screwdriver, you can replace it yourself in a couple of minutes [keeping the usual precautions about working on electrical equipment in mind]. If you are replacing a thermostat, always remember to hand tighten only. Never use a wrench to tighten a thermostat on this machine. If you do not feel comfortable doing repairs yourself, return it or send it in for a warranty repair.


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## timmyjj21 (May 10, 2015)

The boiler looks fine for its age. I've cleaned and refurbished worse.

For starters you will need a new boiler seal, no question about it. Ensure the gasket surfaces are nice and clean. From the pics you have scale buildup and rubber residue from the old gasket in the corners of the gasket groove on the boiler base which definitely needs to be removed.

The boiler top is going to get old and pitted, it's what aluminium does. Refreshing the boiler face can be done with wet and dry sandpaper on a smooth flat surface. Start course and go fine until most of the pitting is gone. Keep even pressure on the boiler when sanding and use a figure 8 movement pattern and you won't have any issues with levelling. I also use a tiny jewlers flat screwdriver to gently probe and scratch any dark oxidised spots and scale deposits to ensure it isn't pitted and needing more attention. Don't worry about making scratches since you are sanding it anyway! All scale pockets need to be removed where the gaskets sits otherwise it will leak again, and unfortunately this is where most of the bad pitting occurs.


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## 00bins (Aug 21, 2016)

I received my gasket kit yesterday, and having already sanded the base of the boiler to within an inch (or more like a micron) of its life I eagerly put it all back together (but only replaced the bottom gasket ). It then leaked from the top of the boiler so I replaced that gasket too, and all is good. So far.

I've run loads of water through it and made 3 doubles this morning and no sign of a constipated pump/solenoid etc...

So thank you all for your suggestions, help and encouragement. 6 quid and some lessons learned is well worth it.

Rob


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## 00bins (Aug 21, 2016)

00bins said:


> I received my gasket kit yesterday, and having already sanded the base of the boiler to within an inch (or more like a micron) of its life I eagerly put it all back together (but only replaced the bottom gasket ). It then leaked from the top of the boiler so I replaced that gasket too, and all is good. So far.
> 
> I've run loads of water through it and made 3 doubles this morning and no sign of a constipated pump/solenoid etc...
> 
> ...


Well I spoke too soon. After 3 cups today it did the same thing again. Once again running it with no water 'fixes' it. In addition when I do this I can see the pump pushing water out through the hose that it should normally pull from.

I'll have another go at the solenoid today but it's getting tiresome.

pah!


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## 00bins (Aug 21, 2016)

So a small update... It's been working but getting worse and worse. The coffee it produces has been flavour-less, crema-less and horrid. Today it packed up again with that constipated sound. Tonight I took off the solenoid valve and cleaned it. No joy. So then i decided to take off the pump and pull that to bits. After cleaning and reassembling (not always with all the pieces in the right order) I realised that the tiny ball that's meant to be on the end of a spring was actually falling through it. I managed to twist the spring a bit so that the ball sat on the end and voila - it's pumping again.

Since then I've found posts and ebay ads about these balls wearing out and replacements. Since i've probably jaffed up the spring I'll probably just buy a replacement pump. At least it might keep me going until I get another one

Cheers

Rob


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## timmyjj21 (May 10, 2015)

ahhh.... So it was the pump. No wonder the symptoms were weird. Picked it the first time around way back in post #8, oh well...


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## 00bins (Aug 21, 2016)

timmyjj21 said:


> ahhh.... So it was the pump. No wonder the symptoms were weird. Picked it the first time around way back in post #8, oh well...


You did










I resisted the urge to test it last night - it was 12.30 am when I finally had everything back in and working (well pumping at least).

This morning I've made 3 pretty good espressos so far, pump sounds normal.

I'll order a new pump anyway because I don't think my fix will last that long.

One other thing last night I found what looked like a tiny piece of cellotape (about 2mm squared, folded over a few times) inside the pump. That can't have been helping either but no idea how that could have got in there.

Cheers

Rob


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## 00bins (Aug 21, 2016)

Pump arrived Tuesday. Fitted. Fixed.

Thanks for all your suggestions - I know a bit more about my Gaggia now too!

Rob


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## seeq (Jul 9, 2011)

Glad it's all fixed. Got to love the classic for how easy they are to fix. Even if not so easy to diagnose!


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## tz1_1zt (Dec 15, 2017)

00bins said:


> Pump arrived Tuesday. Fitted. Fixed.
> 
> Thanks for all your suggestions - I know a bit more about my Gaggia now too!
> 
> Rob


Many thanks @00bins for seeing this through and posting all the details. My Classic was suffering from exactly the same symptoms as in your original post. Glad I read all the way to the end and discovered the solution.

My new pump (only £13 off amazon) arrived yesterday from reseller KGA Supplies Ltd, _exactly_ the same as one in the machine. Swapped them over, after watching this youtube video for moral support. Everything is now back to normal;

- Pump sound effortless and no longer rattles away. I had no idea this was even occurring, it must have deteriorated slowly.

- Works tirelessly on my very fine Pact Coffee delivery, with a nice slow trickle and good tasting brew.

- No longer pumps for a while then stops flow and sits there humming at me.

- No longer teases with a normal flow when cold, but refuses to work when warmed up.

Pump change video


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## 00bins (Aug 21, 2016)

tz1_1zt said:


> Many thanks @00bins for seeing this through and posting all the details. My Classic was suffering from exactly the same symptoms as in your original post. Glad I read all the way to the end and discovered the solution.
> 
> My new pump (only £13 off amazon) arrived yesterday from reseller KGA Supplies Ltd, _exactly_ the same as one in the machine. Swapped them over, after watching this youtube video for moral support. Everything is now back to normal;
> 
> ...


You're welcome. By coincidence, I almost ended up having to replace my pump yesterday _again_. I have my Classic on a time so that in the morning it's already warmed up. Unfortunately I didn't check and left the brew switch on as well as the power switch. When I got downstairs there was a weird sound coming from the kitchen. The reservoir was completely empty, the machine was really hot and when I refilled the reservoir it made exactly the same constipated sound. I almost bought a pump but waited for it to cool down and all seems well now.

It's a testament to how well made and sturdy the Classics are

Rob


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