# Gaggia Classic Pump problem? Pressure Gauge test



## GiovaD (Jan 18, 2021)

Hi all!

I mounted my pressure gauge to my portafilter to my Gaggia Classic 2002 today because I wanted to adjust the opv valve.

I have tried as best as I can to turn the screw of the head of the opv valve, but I found out it to be stuck. No matter the force applied I could not get it to turn. I believe it must be clogged with scale since the opv also doesn't open at any given pressure (also 14 bar pressure).

What I noticed afterwards by checking with my pressure gauge was that the machine behaves a bit strangely (watch the linked YouTube video) : The pressure rumps up to around 14 bars and then settles at around 8,5. When it does settle at that pressure the pump is very quiet. Then I turned the nob of the steam valve while brewing and the pump suddenly rattles and becomes way more loud; the pressure ramps up and stays constant depending on the flow from the steam wand.

Is there something wrong with my pump? Or is it because of scale? Or could there be another cause for that?

Moreover, what can I do in order to unscrew the opv valve? I didn't actually have a proper ratchet screwdriver and I believe with the right tool I could unscrew it, I'm not sure I will succeed though.

Here is the video of the referring problem:


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## El carajillo (Mar 16, 2013)

Firstly don't run the pump for several minutes at a time they are only intended for short bursts./

It looks as if the OPV is stuck but releases suddenly then shuts again ? Try running again and watch the OPV / hose as the pressure drops, is there a small shot of water returning ? Is the adjuster the in the opv the slotted type or the hexagon centre or both ? Has / do you de-scale the M/ch ?

Initially you could try a strong d-scaling solution carefully dripped / poured into the OPV and leave it to soak OR remove it and soak it in a container of -de-scaler . Take care not to force/ strip the slot or hexagon or you will need a new OPV. Sort the OPV first :good:


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## PACMAN (Feb 11, 2021)

It's very hard to tell what you are doing with the steam valve during the video but it needs to be left alone when checking the brew pressure. If you open the steam valve, it is going to remove / reduce the pressure at the brew head. Have you taken the 17mm nut off the top of the OPV? (the V in OPV is valve, so it's not an OPV valve)

Assuming you've got into the OPV and are trying to turn the internal brass part with a 5mm (?) hex key and it's that bit that's not turning, you'll probably be best of completely removing the OPV and soaking it in a (hot) citric acid solution (say 5%) or any other limescale removing solution. Once it has had a good soak (couple of hours) see if you can turn the internal brass part again. You might need to wiggle it clockwise and anti clockwise to 'shift' the limescale and crud caught in the threads.

If, when doing your tests so far (when it gets up to 14 bar), there is no overflow back into your water tank, then it's possible the pump might have been 'overstressed' too many times and is now a bit tired. Depending on what pump is fitted, you can take them apart and service them - the small ball that sits inside the pump might be worn out. See YouTube for pump servicing guidelines.


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## PACMAN (Feb 11, 2021)

From another post, just found this link - might help.

https://www.coffeeforums.co.uk/topic/3412-adjusting-the-opv-over-pressure-valve-gaggia-classic/?do=embed


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## GiovaD (Jan 18, 2021)

El carajillo said:


> Firstly don't run the pump for several minutes at a time they are only intended for short bursts./
> 
> It looks as if the OPV is stuck but releases suddenly then shuts again ? Try running again and watch the OPV / hose as the pressure drops, is there a small shot of water returning ? Is the adjuster the in the opv the slotted type or the hexagon centre or both ? Has / do you de-scale the M/ch ?
> 
> Initially you could try a strong d-scaling solution carefully dripped / poured into the OPV and leave it to soak OR remove it and soak it in a container of -de-scaler . Take care not to force/ strip the slot or hexagon or you will need a new OPV. Sort the OPV first :good:


 The opv is locked I believe, the hose is quite dry and also the barbed fitting is dry and shows some white powder as I could tell. I definitely want to open the boiler and descale it part by part. As of now the machine doesn't show any problem: solenoid valve is working perfectly, flow at brew head is very good, also if I completely open the steam nob and press the brew button water comes out from both ends (brew head and steam wand).



PACMAN said:


> It's very hard to tell what you are doing with the steam valve during the video but it needs to be left alone when checking the brew pressure. If you open the steam valve, it is going to remove / reduce the pressure at the brew head. Have you taken the 17mm nut off the top of the OPV? (the V in OPV is valve, so it's not an OPV valve)


 In the video I was opening and closing the steam nob in order to simulate a dynamic flow (as with a coffee puck) and as I expected the pump behaves very odd. In fact when I open the steam wand, the brew pressure INCREASES, together with the loudness of the pump.


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## larkim (Sep 3, 2018)

Why was the boiler heater element disconnected, btw?

What do you mean by "locked" in terms of the OPV? Can you remove the pipe and remove the barbed fitting top with a socket (the 17mm not as described above)? Can you move / adjust the allen key fitting inside?

Your pump sounds like it makes the same noise as mine when pumping water out through the steam wand. I'd assumed that was normal 🙂


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## Gilly (Jul 29, 2019)

Agree with El Carajillio . Remove the OPV and disk in a solution if Citric acid then rinse well; put it in a vice and carefully use a hex to undo around 1.5 turns roughly.

Two questions:: Why as the pump got cable ties around it?

Why is the boiler element disconnected??


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## larkim (Sep 3, 2018)

If you pull through the OPV outlet hose, or separate it from returning into the water tank, does anything flow through it? Bottom line would be if there is a blind portafilter in there, and the steam wand is closed, you should definitely be seeing some flow back into the tank so it's worth seeing if you can test that out. If you don't see any flow through the OPV back into the tank then the OPV is definitely "not working". The silence from the pump once pressure is achieved makes it sound to me as if it is all simply blocked off. Can't quite explain why the pressure would bounce around once the steam wand is opened up, but that might be by the by.


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## GiovaD (Jan 18, 2021)

larkim said:


> Can't quite explain why the pressure would bounce around once the steam wand is opened up, but that might be by the by.


 Yeah that I believe to be maybe the little rubber ball inside the pump or some orings that maybe are worn out, I don't really know but I do believe it's strange. Also while brewing sometime I hear it "pulsating" and I can see a difference in the flow while extracting.



larkim said:


> blind portafilter in there


 There is no flow coming out of the OPV valve, and no I cannot unscrew the Hex head with the barbed end, it's somehow stuck.



Gilly said:


> Why as the pump got cable ties around it?


 That I don't know, I bought it second hand like that. I'm planning to set the pump free from those zip ties as soon as possible



Gilly said:


> Why is the boiler element disconnected


 Because I didn't want to burn myself and there was no need to heat the boiler since I was only testing the pump and the opv. (I have already done the same exact test with my pressure gauge-fitted-portafilter with boiler turned on and did not behave any differently)

Question: have you had experience of a machine with faulty pump? Is that a problem that may involve the pump seals wearing off?

About the OPV I'm definitely going to open up the machine and the whole boiler and replace all seals and descale everything real good, that includes the opv valve.


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## Paul Steffens (May 18, 2020)

Chipping into this post as my issue may be related.

Picked up a Gaggia Classic 2007 locally for very little and knowing that water was not flowing through grouphead. Thought this could be a blockage of a duct or solenoid valve and that a simple intervention could solve this. Once I got the machine I observed that water flows through neither grouphead nor steamwand. As the pump made noise I did not think the pump itself was the issue. But when I checked the ducts from water reservoir whilst in brew (or steam) function I noticed that no water flows upwards. That explains why no water gets to grouphead or steamwand. There seems to be a small degree of suction as water can rise with up to an inch in the duct.

This suggests there is an issue with the pump. Any observations on what the issue could be? Any recommendations in addition to deep clean and descale of duct from reservoir to pump and then pump itself to address it? Thanks all


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## PACMAN (Feb 11, 2021)

Paul Steffens said:


> This suggests there is an issue with the pump. Any observations on what the issue could be? Any recommendations in addition to deep clean and descale of duct from reservoir to pump and then pump itself to address it? Thanks all


 If you can easily remove the pump outlet pipe from the OPV end (rather than from the pump end) then operate the pump (taking care with any exposed electrical connections) making sure the pump outlet is pointing towards a small container (to catch any water), this will show if the pump is working and if there is a blockage further 'downstream' that is stopping water flow. If there is a full blockage, no matter how hard the pump 'pumps', no water will move from the tank. This will 'half split' your fault finding and allow you to either look towards the pump as the issue, or from the OPV into the grouphead as the issue.


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## Paul Steffens (May 18, 2020)

Thanks @PACMAN. I will follow your advice and see how far I can get


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## BBBean (Jul 31, 2020)

If the machine hasn't been used for a while the pump sometimes seizes up. This is just limescale and the pump can normally be resurrected by dismantling and soaking parts in citric acid solution. There are some really good videos on YouTube showing how to dismantle the ULKA pump. Be careful when disassembling though as some of the parts are rather small and lively (spring propelled).


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## Scouser (Jun 24, 2009)

The other thing that’s really puzzling me is that nothing is coming out of overflow/outlet pipe, which I always tend to think is a solenoid problem but like I say all been cleaned ?


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