Impending failure?

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PJNanook
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Impending failure?

Post by PJNanook » Sun Jun 25, 2017 1:35 pm

I have an interesting situation. When I adjust my grind to get a correct extraction time, the machine goes through these steps.

Preinfusion, the pressure comes up with the normal pump sound, the flow starts, the sound changes to a low buzz and the flow all but stops. It behaves as if my grind is too fine but when I adjust the grind to be more coarse, the flow rate is too high producing a very long shot.

My question is: Is this an indication of something beginning to fail?

It is as if when the back-pressure comes full on the pump cannot sustain it. Could this mean my pump is starting to fail?

Ideas?

Kevin

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chas
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Re: Impending failure?

Post by chas » Mon Jun 26, 2017 1:10 pm

That's a tough one just from your description. We might have a better idea if you could make a video of it with your phone, post to YouTube, then use the above YouTube icon to insert the YouTube link into your reply.
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Re: Impending failure?

Post by chas » Mon Jun 26, 2017 1:16 pm

Some questions:

1) Is it a Mini or a Plumbed model?
2) If plumbed do you have the mechanical pre-infusion or the electronic?
3) Did you really mean that a coarser grind causes a longer shot??? Normally it's the opposite.
4) Based on your Forum Join date, is this a 4 year old machine that just started to exhibit this issue?
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Re: Impending failure?

Post by PJNanook » Mon Jun 26, 2017 1:24 pm

It is a Mini with Mechanical Preinfusion (I think that was all that was available on this model) The machine was purchased in Nov of 2011.

Maybe I don't have the definition of short or long correct in my mind.

Even worse today as far as trying to diagnose. When doing some backflushing, the sound became normal after it failed with a shot just a couple of minutes previous.

I do have an email into Chris' Coffee. They have been very helpful for me in the past. I bought this machine when I lived in Alaska from Seattle Coffee Gear. We now live in the Seattle Area. I may give them a call as well. My first thought would be pump or flow meter. It acts like it would when the grind is too fine but the lights (17-18-19) never come on as the owner's manual states.

What else would you be looking for in a video?

K

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Re: Impending failure?

Post by AndyPanda » Mon Jun 26, 2017 2:18 pm

If you can try to answer some questions, we can help you diagnose.

Does your brew pressure gauge go up to 9 bars when you hear the sound of the pump change to a low buzz?

Do you have a blind basket (a basket used for backflushing - no filter holes) ? Or do you have the rubber disk to block your filter basket for backflushing? Are you able to build up pressure when backflushing and do you get a "whoosh" and water splashing into the drip tray from the backflush?

If your pump is building up 9 bars of pressure and doing a normal backflush then it might be your grind too fine or dose too much.

What does your coffee puck look like when you remove the portafilter after the pump sounded like a low buzz? Does it look like the coffee grounds all got saturated? Or does it look dry? Do you see imprint in the top of the coffee puck from the shower screen?

what grinder are you using?

How are you measuring the amount of coffee you are putting in the basket?

PJNanook
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Re: Impending failure?

Post by PJNanook » Mon Jun 26, 2017 3:04 pm

Happy to answer questions. I know that even the coffee doctors are not clairvoyant. :)

The pressure goes up to the normal range on the gauge. (about 9 bar in the green zone)
I don't have a blind basket, I have the rubber disk.

When I do a back flush, the pressure builds and the the hear the pump change (most but not every time) when I hit the button to stop the pump and release the pressure I get the whoosh since the initial pressure built. When the pump sound does not change (fewer times) the whoosh is louder. The manual says the lights 17-18-19 should light and "is a good indication that when to stop the pump for back flush." Those lights do not come on.

It has been working with this grind. My dose is about 16 grams in a double shot portafilter.

When I try a shot the flow and sound start normal, then the pump sound changes to a low buzz, the flow reduces to almost nothing (maybe a few drips) The puck is then pretty dry. There is a small imprint just in the middle.

Grinder is Baratza Vario

It does act like the grind is too fine but the machine changed behavior with the same grind and roast. This problem, for now, more often than not but with a fraction more coarse grind and just a smidge less dose, my last shot was a full (right to the rim) rattleware cup which would be 2.5-2.75 oz.

I have not checked the time on the dose lately but, i don't know how that would have changed.

The only change in coffee is that now I am on the second bag from the same roast from my local small coffee roaster. (the problem started on the first bag)

Thanks everyone for your attention. Even when I have just researched issues here and not had to ask questions, everyone is always knowledgeable and helpful.

Kevin

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Re: Impending failure?

Post by PJNanook » Mon Jun 26, 2017 5:42 pm

Also, just remembered that for a while now each morning before we pull the first shot, you have to run a bit of water through the group or the shot will be well less than 2 oz. You must do this if the machine sits for a while as well. It only has done this in the last year.

K

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Re: Impending failure?

Post by chas » Mon Jun 26, 2017 6:06 pm

It sounds like you bought the machine with the mechanical pre-infusion already installed. If not, you would have the bolt that goes in the hole where the preinfuser attaches and you could do a quick test by removing it to confirm that it is not causing the problem.
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Re: Impending failure?

Post by PJNanook » Mon Jun 26, 2017 6:31 pm

The preinfuser came preinstalled. I will have to look in the box. I think they shipped the parts with it. It was a while ago.

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AndyPanda
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Re: Impending failure?

Post by AndyPanda » Mon Jun 26, 2017 8:41 pm

The Vario is notorious for changing it's settings by itself. If you are reading 9bars on the gauge and getting the "whoosh" of water when you backflush, I would suspect your grind and dose. Try 14 grams in the double basket. Try one or two micro settings coarser on the grind.

HOWEVER ... Since you say the sound of the pump sometimes changes and sometimes does not when you do a backflush (did I understand you right?), it's possible the vibe pump is weakening or more likely that one of the rubber valves in it is starting to stick. I've opened up the valves on very old vibe pumps that wouldn't pump and gotten them working again ... but a new pump is not terribly expensive and very easy to install.

When you worry about the alarm lights not showing up ... I've only ever seen those alarms once and it was when I forgot and left the blind basket in with the pump running for several minutes. I never see the alarm when I'm doing a normal backflush. I only run the pump with the blind basket until you see 9 bars of pressure and then there is nothing further to be gained by running the shot any longer - once you have full pressure you stop the pump and let it backflush (whoosh).

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Re: Impending failure?

Post by chas » Mon Jun 26, 2017 9:59 pm

Quite a few owners of the Mini have mentioned this. Why the flowmeter alarm on the Mini doesn't work reliably but does work well on the plumbed models is a mystery to me.
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Re: Impending failure?

Post by PJNanook » Mon Jun 26, 2017 10:18 pm

Yes, the pump sometimes sounds the way it always has and sometimes I get the low buzz. Reassuring not know that folks don't see the lights. I do my backflush as you state. Get it up to pressure and the fire it off. I can't remember a time when I did not get the initial build to 9 bars and then the sound changes. (or fewer times does not)

A valve issue in the pump might explain the water leaking back between shots. (when there is quite a while btw shots) As I said, I often have to run the pump before pulling to make sure that the water is flowing. Often there is a delay and then the water flows. It is as if the water is no longer holding in the line. Not having an image of the routing of the plumbing, this is what I picture.

My initial thought was the pump was going.

K

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Re: Impending failure?

Post by AndyPanda » Tue Jun 27, 2017 12:57 am

The vibe pump has two (or three) little spring loaded rubber stoppers - they are supposed to let water go one direction only (towards the boiler) ... so as it vibrates back and forth, it is like a tiny bicycle pump making very short strokes but making 60 of those shorts strokes every second - at least in the USA with 60 cycle electricity.

Sometimes you get a little grit sucked into the pump and it'll stick those valves open. For example - I understand that if you put descaler solution in the water tank it dissolves the plating from the metal fitting at the back. I bought mine used and the fitting is mostly no longer plated and there is a lot of silver flecks I had to clean out.

Anyway ... for most people it's cheaper/easier to just buy a new pump but I have owned a lot of very old and abused vibe pump machines and I've never found a vibe pump I couldn't bring back to life by taking apart and cleaning. I'm handier than most though :)

One reason I believe Chas asked for a video (I'm assuming here) is that it is normal for a vibe pump to quiet down and change sound when you lock it up (like with a blind filter doing a backflush). But you are saying sometimes it does and sometimes it doesn't and you are describing it as a "hum". So we are really guessing at what sound you are hearing - and a video would let us hear and be able to say "that's something wrong" or "that's normal".

And as I recall ... when a valve is stuck open, the noise doesn't quiet down to a hum ... seems to me like it stays noisy and loud but just not much water flows. So a stuck valve may not fit your description at all.

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Re: Impending failure?

Post by PJNanook » Tue Jun 27, 2017 11:21 am

I will see if I can get a video. It helps a lot to know what I need to show.

I too am pretty handy but over the years, I have come around to the idea that some parts are cheaper than my time. (some are not)

K

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Re: Impending failure?

Post by PJNanook » Tue Jun 27, 2017 11:27 am

You said that the valves are supposed to only let water one way. W often have to run the pump a bit to get any water out of it if the machine has not been used. Frequently overnight and occasionally just a half-hour or so. This is so much the norm that now we always pull a little water through the machine before we even start to grind any coffee.

K

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Re: Impending failure?

Post by chas » Tue Jun 27, 2017 11:44 am

There's one of those one way valves built-in right behind the tank to keep water from running back out and into the tank. If this valve is leaking water back into the tank perhaps the pump could partially lose its prime the next time it is run.

To test this I guess you could pull the tank out for a while after pulling a shot and see if you get a puddle.
Chas
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Re: Impending failure?

Post by PJNanook » Wed Jun 28, 2017 11:45 am

Thanks, I will test that. It makes some sense as I might leak back if the tank was no so full and not when the tank was full.

I should have time to make a video tomorrow. The folks at Chris' Coffee asked for a video as well.

Today, I successfully pulled a shot at 13 grams. It just seems to me that this thing is on a razor's edge of where it works or not. Since it never seemed that way before, it leads me to believe that it either needs some internal cleaning or is on the verge of failure. With me only having this one machine as my experience base, I am grateful of you helpful here at the cafe who are willing to help me work through it.

K

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Re: Impending failure?

Post by PJNanook » Sun Jul 09, 2017 4:48 pm

Finally able to capture the problem on video. Hopefully, I will be posting it soon. Now a problem with my primary computer. Think one not really up to video.

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Re: Impending failure?

Post by PJNanook » Sun Jul 09, 2017 7:07 pm

Computer seems to be behaving so I was able to figure out Youtube. I am a photographer not a video guy. :)

As happens often as I have been nursing the machine along this week, the next shot was perfect with no change in settings.

https://youtu.be/ZrcOeWVBqXM

I hope this worked.

K

PJNanook
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Re: Impending failure?

Post by PJNanook » Mon Jul 10, 2017 6:00 pm

Chris' Coffee service says based on the sound it is the pump. I may try Seattle Coffee Gear for the repair since they are local. (and who we bought it from. We were not local at the time.)

While I could probably do it, I am not really wanting to.

K

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Re: Impending failure?

Post by PJNanook » Thu Aug 17, 2017 12:44 pm

Well it finally just said no. Pump replaced. All is back to normal.

Kevin

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chas
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Re: Impending failure?

Post by chas » Thu Aug 17, 2017 12:50 pm

How much did Seattle Coffee charge for parts & labor? Were you able to physically take it there rather than shipping?
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Re: Impending failure?

Post by PJNanook » Thu Aug 17, 2017 1:41 pm

About $255 including the homage to the governor. That included the pump, descale, general cleaning and replacing the gasket (that I supplied) I was able to drop off and pick up. I live about an hour south of their repair facility.

Pretty quick turn around. If I had brought in on the day I picked it up, that might not be the case. The gentleman told me that he had 30 repairs come in.

Also when I was there, they just got a delivery from Rocket. I could see 26 pallets of machines. It appears that their business is strong.

Kevin

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