# Rotary pump leaking



## John Yossarian (Feb 2, 2016)

Hello All,

Several hours earlier I posted about the successful heating element replacement of my Appia 1 gr. I pulled a few shots happy with its performance.

Later I switched the machine on for our lunch coffee and after 20 minutes my wife noticed a large puddle of water on the kitchen floor.

When I looked it turned out that the pump head is leaking water via the valve where one adjusts the brewing pressure.

I have not opened it yet to see what the issue is but I would like to know your opinion what the chances are that this can be fixed.

When I was descaling the boiler I did also descale the pump head in a 5% of citric acid (for no more than 10-15 minutes). If I have shortened the life span of the pump I will have to buy a new one.

Thank you in advance!

Cheers,

John


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## DavecUK (Aug 6, 2013)

Just replace the O ring on the balanced bypass...


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## John Yossarian (Feb 2, 2016)

DavecUK said:


> Just replace the O ring on the balanced bypass...


 Thank you so much Dave!

Cheers,

John


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## DavecUK (Aug 6, 2013)

Just a tip, make lubricating it (o rings) part of annual maintenance....helps make it last much longer...Molycote 111 is your friend.


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## John Yossarian (Feb 2, 2016)

DavecUK said:


> Just a tip, make lubricating it (o rings) part of annual maintenance....helps make it last much longer...Molycote 111 is your friend.


 Hi Dave,

I have done as advised. Replaced the o-ring, used silicone food grade lubricant and no leaks. Thank you!

The issue I am facing now is that the pressure inside the pump cavity (that when idle should be the mains pressure) keeps on going up. Switching the pump releases the pressure and it gets back to the mains pressure but in a few minutes it keeps on raising.

Any idea why this might be happening? I cannot see where the extra force would be coming from to raise the pressure?

Cheers,

John


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## DavecUK (Aug 6, 2013)

How and where exactly are you measuring this pressure?


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## John Yossarian (Feb 2, 2016)

DavecUK said:


> How and where exactly are you measuring this pressure?


 This is the pressure gauge on the machine split in two, one for the brewing pressure (and the pressure when the machine is idle) and the other for the boiler steam pressure, usually between 1 and 1.4 bars. The idle pressure used to be around 3-3.5 bars and now it settles at 5 bars. Unless United Utilities have recently raised the pressure in the mains, then I have no explanation. It could be a red herring but when I first time installed the pump (after replacing the o-ring) it started raising to almost 6.5-7 bars.

Now it idles at around 5. When pulling shots the brewing pressure is around 8.5-9.

I will leave it for another couple of hours to see what happens.

Cheers,

John


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## DavecUK (Aug 6, 2013)

So what you really mean is pressure in the brew circuit, not the pump cavity....Brew circuit is sealed system 1 way valve after pump, water expansion on heating after a shot raises the pressure, shows everything is all good. Prior to your descale, the 1 way valve was leaking which would have limited the pressure valve to mains pressure. Don't worry about it.


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## John Yossarian (Feb 2, 2016)

DavecUK said:


> So what you really mean is pressure in the brew circuit, not the pump cavity....Brew circuit is sealed system 1 way valve after pump, water expansion on heating after a shot raises the pressure, shows everything is all good. Prior to your descale, the 1 way valve was leaking which would have limited the pressure valve to mains pressure. Don't worry about it.


 Thanks Dave!

I kept it for another two hours and all seems OK now.

I very much appreciate your help!

Cheers,

John


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## John Yossarian (Feb 2, 2016)

Last night I believed that everything was fine. Unfortunately the saga still goes on.

This morning the machine, when switched on and after the machine heated up, the pressure in the brewing line reached 7 bars and as a result, the pump head started leaking via the bypass valve.

Has anyone had ? a similar issue and if yes, how have you managed to solve it?

Cheers,

John


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## John Yossarian (Feb 2, 2016)

After a couple of weeks of using the machine (no more was I able to use my timer in the mornings) today I took a picture of the pressure gauge when the machine heated up. The pressure in the brewing line reached 10 bars before i pushed the button and let some water flow through the group head at which point the pressure went back to 3-5 bars. During the heating I have to repeat this 2-4 times as otherwise the pressure will exceeds 12 bars. At certain point the bypass valve would open and the kitchen would be flooded unless I am around at 5 am in the morning.

I really hope someone could tell me whether this is normal (I doubt it) but if not what the culprit might be. I am even considering buying a new pump head but I still believe it might not be necessary.

Cheers,

John


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## grumpydaddy (Oct 20, 2014)

John, I have a couple of pumps here, well at work anyway, If it is determined that that is the fault or you just want to substitute for testing we would need to determine the suitability first but you are welcome to borrow for a while


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## John Yossarian (Feb 2, 2016)

Grumpydaddy, Thank you so much for your kind offer!!

I hope someone would chip in with the advice I so badly need.

Cheers,

John


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## DavecUK (Aug 6, 2013)

The pump has n inlet and outlet, there is often a spring in the pump Looks like it just sites in the bore, it's there to keep the bypass valve in place, you have not removed it perchance or fitted it on the wrong side of the pump?


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## grumpydaddy (Oct 20, 2014)

I have no knowledge of this but I would guess that when you push the button for a shot, a valve opens and the pump is switched on.

The only thing the pump seems to do is pressurise, there are no on/off valves but there may be bypass control that is sticking.....so unless there is some form of other valve control which is not closing I am in the dark.

A job for a coffee machine mechanic or a CFUK oldtimer with the knowledge of how this works

Ha, while I am typing just such a person posts


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## John Yossarian (Feb 2, 2016)

Thank you both for very valuable information!

I will open the valve and will check the innards. I know the spring Davis talking about and will look into readjusting it.

Cheers,

John


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## DavecUK (Aug 6, 2013)

Just in case this is the spring I mean, people sometimes don't realise what it's there for. I have also put in a .pdf for a pump that's similar to yours. It must either be spring in wrong bore, or perhaps the bypas O ring you use isn't the right size. However you can check all the parts and how they fit again.









View attachment co-50-200-rotary-vane-pump-spare-parts.pdf


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## John Yossarian (Feb 2, 2016)

Thanks Dave

I would have never suspected this spring in particular but when I descaled the pump I saw it. I will check it again.

Cheers,

John


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## DavecUK (Aug 6, 2013)

Just check it's in the right hole otherwise the bypass valve can move too far.


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## John Yossarian (Feb 2, 2016)

Hi Dave

The spring is there, I have just assembled it back. It is in the right hole, the outlet. I have struggled to find the exact size of the Viton o-ring. The one I have been using was too tight making the by-pass plunger almost immobilised.

I cannot see anyone selling the right size, which should be 18B according to your diagram.

Do you think if I dropped a line to Fluid-o-tech they would entertain such a small order?

If I cannot find it I am also considering going for a new water pump head.

Cheers,

John


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## El carajillo (Mar 16, 2013)

Try a pneumatic or hydraulic engineer / or supplier :good:


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## DavecUK (Aug 6, 2013)

Back to my first comment on this, you need an O ring the right size, I presumed you had purchased the right part. Buy an O ring kit, edpm rings are fine, these kits have 100s of o rings in of all sizes and find a size that works, then hang on to the kit for other little o ring jobs...they are only around £6-8 for lots of sized o rings in a box. Something like this with a good range of sizes. The spring was the only other thing if you had the o ring of the right size. The plunger should move fairly freely the O ring reasonably snug on the shaft...the pressure effectively expands the ring sealing everything. lube it with molycote 111.

https://www.ebay.co.uk/itm/419-PCS-RUBBER-O-RING-ORING-SEAL-PLUMBING-GARAGE-SET-KIT-32-SIZES-WITH-CASE-4-34/282242200141?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D59535%26meid%3D105e8f18aa3a4ad18c1ebc679204d5f6%26pid%3D100005%26rk%3D2%26rkt%3D12%26mehot%3Dpp%26sd%3D173623210700%26itm%3D282242200141%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851


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## John Yossarian (Feb 2, 2016)

I have got exactly the same kit at home. The one I picked from it was a bit on the tight side. I will try again.


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## John Yossarian (Feb 2, 2016)

I thought I should make an update where I am with the machine.

As I could not find the right o-ring and I did not believe it was the o-ring only (the plastic plunger did not look right) I ended up splashing some cash on a new water pump head. It was almost 2 cm (longer/wider?) but I have managed to accommodate it.

First time I started the machine the move in pressure upon heating was back and I was very disappointed, but after the second use the machine went back to normal, i.e. upon heating the pressure in the brewing line would stay constant equal to the mains pressure.

The ting that has changed since the replacement (why could not things stay the same?) is that now the soft infusion cycle is almost missing. In the past I would have a few bars pressure for a few seconds before the pump would reach 8.5-9.0 bars. Now upon switching the brewing button, the pressure almost immediately hits the top.

I have checked the puck and it is very dense and well wet inside, I dissected it to see.

I have always believed that the infusion is controlled by the "black box-brain" of the machine and it provides the pump with step-wise change in the current going through the motor. But now, after changing a mechanical part I am not so sure.

Can anyone shed more light if they know what might happened?

Thank you in advance!

Cheers,

John


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## El carajillo (Mar 16, 2013)

You 'assumed' ? the black box gave the soft infusion. Is this fact from anywhere ?

If the old pump was leaking pressure, this would give a slower ramp up of pressure.

The new pump will kick in immediately without any pressure loss= instant ramp up .


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## John Yossarian (Feb 2, 2016)

El carajillo said:


> You 'assumed' ? the black box gave the soft infusion. Is this fact from anywhere ?
> 
> If the old pump was leaking pressure, this would give a slower ramp up of pressure.
> 
> The new pump will kick in immediately without any pressure loss= instant ramp up .


 Hi El carajillo,

Thank you for your note!

I know that assumptions are always subject of scrutiny and more often than not they fail.

My old pump started leaking lately, after I de-scaled it (I most likely have shortened its life span but that is a different topic and I stand corrected) but before this happened it has been doing the soft infusion for more than two years.

I do not believe that the soft infusion should be water pump head specific and this is why I posed the question.

What would be your suggestion? I honestly do not know and if my assumption was wrong, what then has changed and I do not get it anymore.

Cheers,

John


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## El carajillo (Mar 16, 2013)

Does the faster ramp up change the taste in the cup ? is it noticeable ? Providing you are happy with the coffee you are brewing I would use the machine as is.

Looking at different sources there appears to be a query as to IF the single group has the SIS fitted. Someone else asked the question and the suggestion was to change the geicleur valve (jet) from the standard 0.8mm for the 0.5 mm, this slows the ramp up but does not affect the final pressure.

You can test to see which jet you have in, run water through the group for 15 sec's and weigh / measure this output. If it is more than 200 ml /gms you have the 0.8 jet fitted.

@ Spenner did work on this a couple of years ago working on his Verona, he changed from 0.8 to 0.5 and found an improvement.

Hope this helps.


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## John Yossarian (Feb 2, 2016)

El carajillo said:


> Does the faster ramp up change the taste in the cup ? is it noticeable ? Providing you are happy with the coffee you are brewing I would use the machine as is.
> 
> Looking at different sources there appears to be a query as to IF the single group has the SIS fitted. Someone else asked the question and the suggestion was to change the geicleur valve (jet) from the standard 0.8mm for the 0.5 mm, this slows the ramp up but does not affect the final pressure.
> 
> ...


 Thanks a lot!

When I recently have descaled the machine I looked at the gicleur and I believe they were the larger size. I will do the experiment as you suggest.

The coffee is still good, the puck seems exactly the same and well soaked across.

I might stick to the "do not fix it if ain't broken" rule and just enjoy the coffee as is.

Thank you again!

Cheers,

John


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## espressotechno (Apr 11, 2011)

Just fit a new pumphead....They're not expensive & life's too short......


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## John Yossarian (Feb 2, 2016)

espressotechno said:


> Just fit a new pumphead....They're not expensive & life's too short......


 This was exactly what I did driven by similar thoughts .

The new pump head has a larger debit and as a result I have lost the SIS (I have checked it with Nuova Simonelli). I need a pump head that delivers 50 l/h I have got one that delivers quite a bit more, between 100 to 200 l/h.


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