Pressure fluctuations. Unable to hold it!!

[dgasmd]

Today I feel like I want to kill myself I noticed yesterday that when I was pulling a shot there was a sound a little unusual about the pump. It also seemed like it took a long time to take the double. I don't use a timer every single time I pull a shot, but it sure felt like a lot longer than usual. I later made another and as soon as it started, I noticed the pressure went to 9 as usual, but a few seconds later it dropped to4-5 while making the unusual sound from earlier. I had the timer on, so I could see it was taking way way too long. By the end of the shot, it went back up to 9 on the pressure gauge. I noticed a few drops of water leaking from around the portafilter. That was my last short of the day. This morning, I went to do another shot and the same thing happened. I took apart the portafilter, the screens, and replaced the thick rubber washer thinking it was so shrunk that it was leaking around it preventing the pressure from building. After everything was clean, I put it together and the same happened.

Any suggestions or ideas short of sending this back!! It had been working flawlessly for 8 months!

[richardcoffee]

After you cleaned up the screens and installed new gasket, did it still leak around the portafilter? Have you been backflushing with detergent? Is the machine only 8 months old? Have you called Chris' - I've found them very helpful in telling me what to look for. I know this doesn't help directly, just trying to get as much info. as might be relevant. Have you tried seeing how much water you get through the group in 30 seconds without a portafilter in?

[chas]

I've never owned a Mini but when similar reports have been made it the past it often ended up being a clogged water filter in the water tank. If you just disconnect the water filter and then pull some shots, you will be able to quickly rule this in or out.

[dgasmd]

No filter in the water tank. I run mine without it as the water I use has 30 ppm making the in tank filter useless basically. As far as the water leaking, it was more like a couple of drops. No more. That did not occur again after the gasket change, but it did not solve anything either. As far as backflushing and such, I clean the screens and disperser block weekly. Back flush as well. Yes, machine is 8 months old.

Spoke with someone at Chris. Given not a single thing has changed whatsoever in the last 8 months, they wanted to make sure I rule out the pump itself. After putting the rubber disc in the portafilter, I pulled a shot. Pressure held at 9 for quite a while all 4-5 times we did it. He suggested it may be the coffee itself. Turns out that coincidentally I did get a new batch of coffee a couple of days ago. Same type and vendor as in the last 8 months. He said sometimes even the best roaster have a bad batch and that he suspects it is the culprit. Since I live in the middle of the twighlight zone for coffee, I don't have any local roasters to get a lb to play with and see if it works out fine with it. The closest I get is to get a bag of either starbucks or dunkin donuts beans and try it. So, I did. After using almost 1/2 bag of starbucks espresso beans (which feel very oily to the touch), I am nowhere closer to ruling it out. Tried so many grind combinations with the same total weight. Sometimes it was so fine the shot would take 1:10 to come out and yet the gauge would show it as 4-5!! Sometimes it was so coarse it would run right through it and still show the same. It could be these coffee beans are chit also, but I have more doubts now. Of course, this crap only happens on a friday afternoon after everyone leaves work early. Tried contacting the original bean vendor I use, but they had already left for the day. Just hopping I don't get a seizure from caffeine withdrawal by monday!!

Any suggestions???

[richardcoffee]

Others may know better, but if pressure is holding with the blank, it seems to me it has to be either the coffee, your grinder or both. Starbucks espresso beans are not a good test. Alas! I experienced something similar today with my own roasted decaf beans that I took a little too dark.

[Endo]

If not the coffee or filter, I suspect the gauge.

[chas]

Some thoughts:

1) To rule out the coffee, use a blind filter basket or rubber plug in the basket like you do for group cleaning. Run the machine for 10-15 seconds in this mode and see if the pressure also drops or if it is able to hold 9 bar.

2) If you see the same pressure drop happening in step 1, I would trace all the vinyl tubing between the tank and the pump inlet with the machine running to be sure that the pump suction isn't partially collapsing the tubing. If that is happening it would also explain the noise you are hearing.

3) If you don't see anything like that happening, it is also possible that the pressure adjustment valve is partially sticking open. However, if that was happening I would expect the occurrence of the problem while pulling a shot to be more random.

4) The other thing to try would require that you build a portafilter pressure gauge. (Search this forum to find how other owners have built one.) With that you can determine if the fluctuation is also seen at the group or only on the gauge. The built-in gauge is closer to the pump that to the group head and the water path to each splits such that it is possible to have an issue along one path without affecting the other. (See the water diagram in the on-line manual.)

[dgasmd]

Thanks again for the replies and insights. I did do the bit with the disc on the portafilter several times and for various time duration. It went up to 9 and stayed there every time. However, when pulling a shot it would drop to 4-5. After adjusting the grind from so fine the grinder would stop to the other extreme, I noticed the pressure would drop every time with the coffee regardless of whether the water was flowing through it fast or not even flowing due to the grind being too fine.
Spoke with Chris coffee again about the findings and they think now it is very likely the pump. They sent me a replacement one right away, and it should be here either today or tomorrow. They'll talk me through the installation over the phone. That should be interesting LOL....

[chas]

We've had folks with the plumbed in S1's replace pumps and motors and have that pictorially documented here in the forum, but I think you may be the first one to do this for the Mini/vibe pump variant. It would be great if you could fully document the process and post photos and text here when you are done.

[dgasmd]

I'll try

[Endo]

The pump? That would be a first.

These Ulka pumps are very simple and reliable and I've never heard of one going bad after such a short time. Besides, if it did fail, I doubt it would fail and produce the results you described.

Maybe I'll be proven wrong, but I still suspect an upstream restriction or the gauge itself.

[richardcoffee]

It just doesn't make sense to me. Why should it matter what is in the portafilter restricting the flow - coffee or a rubber disc? The gauge should behave the same shouldn't it?

[Endo]

It just doesn't make sense to me. Why should it matter what is in the portafilter restricting the flow - coffee or a rubber disc? The gauge should behave the same shouldn't it?

If something is sticking (like the gauge or an OPV), it might react differently to different downstream blockages.

I had a similar drop in pressure on a LeLit that I just repaired (see the video on my blog at: http://cremina-endo.blogspot.ca/2012/06 ... v-fix.html). Turned out to be a sticky OPV.

I also first suspected the pump, but it turned out to be fine in the end.

[chas]

It just doesn't make sense to me. Why should it matter what is in the portafilter restricting the flow - coffee or a rubber disc? The gauge should behave the same shouldn't it?

Pressure should be the same in either case on a correctly functioning machine, but obviously something is amiss here. Since the pressure regulator valve in the Mini connects from the output to the input of the pump, holding 9 bar with the backflush disk in place requires very little water since the water flow is completely from the output of the pump back to the input. However, when water is flowing through the PF the pump has to maintain pressure while water is flowing. The two reasons I can see for the pump not being able to do this are either a) bad pump b) restriction in tubing between the tank and the pump inlet.

[chas]

The pump? That would be a first.

Maybe I'll be proven wrong, but I still suspect an upstream restriction or the gauge itself.

One reason I recommended running the pump with the backflush disk in place was to check the gauge. Since the gauge consistently holds 9 bar with the backflush disk in place, it's hard to believe the gauge is the issue. Also if it was the gauge, I would expect the error to appear more randomly across a shot rather than for the pressure to show a consistent curve with each shot. ( I also think the consistent 9 bar with the backflush disk in place lets the pressure regulator valve off the hook. **)

I still wonder if the vinyl tube between the tank and the pump inlet might be partially collapsing. It seems to me that it either has to be that or the pump.

** I still think that while dgasmd is changing out the pump, it would be good to disassemble, inspect, and clean the Pressure Regulator Valve. The Mini uses the same valve used in the Maxi. However, the Maxi uses this valve to dump water from the group boiler into the drip pan in case of group boiler over pressure. This valve consists of a spring loaded plunger with a rubber disk on the end that pushes against the end of a tube with a smaller diameter than the rubber disk. If the rubber disk gets worn, misshapen, or cracked or if the tube is hitting the disk way off-center, it can leak. These cases are pretty easily visible by inspecting the end of the disk as well as the impression the end of the tube makes on the disk. If necessary, you can just get a replacement rubber disk; you don't need to replace the whole valve.

As used in the "Maxi", this disk opens at most once per boiler heating cycle. However, when used as a pressure regulator valve in the Mini, it opens and closes many times per second each time a shot is pulled. So there may be much more wear and tear on that rubber disk on the Mini. (If you see the group pressure gauge needle vibrating on your Mini while pulling a shot, this vibration rate is the rate at which the pressure regulator is opening and closing.)

[Endo]

I know it seems weird that you would get full pressure with a disc in the PF and only half pressure with coffee, but I may have an explanation:

The OPV valve moves like a little piston several times a second when open. When the rubber valve seat on the bottom of the piston moves up, the water flows around the piston between the narrow passage between the piston and housing walls. Any thin buildup of junk on the the psiton sides or housing walls (like rust, scale, foreign particles, etc) can increase friction enough to stop the piston from vibrating smoothly and quickly. Instead of vibrating whicjh gives it the characteristc needle vibration on the gauge around 9 bar), it sticks fully (or partially) open when flowing and produces a lower average pressure (since it never actually fully closes).

One way to see if this is the case is to look at your gauge needle closely when it is at 4 bar. Does it vibrate like when at 9 bar or not?

It could be this doesn't happen with a backflush disc since the pressure buildup is much quicker than with coffee. So the OPV is "kicked" past the sticking point quickly and it vibrates normally. (I experienced this first hand on another espresso machine).

I would do as Chas suggested and open the OPV, clean it out and reassemble, BEFORE changing the pump. It's very easy to do from the front of the machine.

Changing the pump may SEEM like it fixes your problem temporarily (if the pump pressure and pressure ramp-up is slightly different), but the problem will reappear if the OPV sticking gets worse.

[dgasmd]

WOW, you guys know your stuff. I can barely say I know how to pull a shot and you guys are diagnosing cancer and treating it in a sense LOL............ This is very good to hear. I must admit that after I saw the link above and read through it, I was convinced that had to be the cause and not the pump, but the other explanation above also makes sense. I will discuss it with the people from Chris coffee when I get them on the phone to talk me through the installation. Maybe they can talk me through the cleaning of the OPV valve as well as simple as it may be. The pump's installation should be pretty straight forward as I see the new one here. All it has is an inlet, outlet, and a place for 2 wires to go in. Frankly, I don't ever see a place to bolt it down to something, but I am sure that will be self evident once I open up the machine. Will take pictures for sure if anything for my own sake, and just in case I can't figure out how I undid something.

[dgasmd]

OK, so the SAGA has come to an end in a positive way. Hard to think there were 2 culprits tot he problem, but the biggest factor was the machine.

1. The coffee I recently got was bad. No way to tiptoe around it. It never smelled or tasted like what I have been getting from the same vendor for 8 months now. Regardless of what caused it, I tried everything suggested by the roaster to try to remedy it and then some to the extremes. Nothing really helped in the end. They ultimately gave me credit for 2 of the 3 bags I ordered and asked me to continue to try the other in hopes of maybe giving it a few days out of roasting would change things. I hasn't, so I will contact them and let them know. In the meantime, I ordered another batch from them. Right from the moment I opened the new bag I could tell I was not crazy. The smell and taste of it was undeniably different, and more along the lines of what I was used to. I tried it, and right off the bat it was exactly what I was used to. Sometimes some things are out of sync with a roast. It apparently does not take much to make a significant difference.

2. The main culprit seemed to have been the pump all along. Chris Coffee had sent me a new replacement one, and it got here yesterday. Today I had a lot of things to do, so it was not until about 3:30 pm that I got a chance to call them and have them talk me through by phone on how to install it. Like I said before, it couldn't have been that difficult as there was only 2 wires and 2 hoses. The disassembly of the rear panel was pretty easy and straight forward so long as you knew which screws to take off and loosen up. The pump was very accessible and right in front to clear view. I did discussed with them the suggestion of a clogged OPV valve, and they dismiss it completely. They said in this case it was either the pump itself or the adjustment valve for the pump's pressure. They just did not seemed concerned or worried about the valve and were pretty confident it was the pump. In the end, I had nothing to loose by replacing it and seeing if it solved the problem. After I replaced the pump, which took 10 min mostly due to me not finding the roll of teflon tape I had somewhere in my tool box, I turned on the machine and brought everything back up to temp. Given I sat there waiting for it to do so, I was amazed how quickly everything got up to temp including the boiler for the steam. I first tried running hot water and some came out. Not much. I then tried to just run water through the group and hardly any came out. Then, it quickly stopped with the machine turning off. I called the guys back, and they talked me on how to prime the pump and machine a couple of times. Seemed the pump lost prime while being swapped. Tried once again to run water through the group and it was fine. Pulled the first shot and it was too quick. I did not have my grind adjusted to where it was for this type of coffee. Once I adjusted it back up, the third shot was fine, and the pressure was holding back at 9 again. 2 more shots and a couple of trials with the rubber disc with the same results. So, in the end, it seems the pump itself was the culprit.

I asked them why they thought this went out so early, and if there was anything I was doing or could avoid/change to prevent it from happening again. Their answer was that it would be nearly impossible to tell unless they took apart the old pump and tried to see what in it failed. It may still not answer the question. They also said something that many of us too often forget. "It is a man made mechanical part. They all fail, some sooner than others. These are somewhat generic pumps that are used in many different brand and types of espresso makers. They fail at varying rates sometimes without obvious causes."

I did take pictures of the entire process. I need to upload them and explain it step by step as requested though.

[Endo]

I did discussed with them the suggestion of a clogged OPV valve, and they dismiss it completely. They said in this case it was either the pump itself or the adjustment valve for the pump's pressure. They just did not seemed concerned or worried about the valve and were pretty confident it was the pump .

There is no such thing as an adjustment valve for the pump's pressure. The pump delivers a flow and the max pressure is determined by the OPV setting. You can think of it as a maximum pressure limiter.

In any case, I'm glad to hear you found the source of the problem. That's the first vibe pump I ever heard of going bad so it will be interesting to see if others eventually show up as well. Let's hope not!

You should try opening the old pump to see if you can find the cause of the problem. Pretty easy actually. It's interesting to see the simple mechanism and the tiny plastic check valve.

[dgasmd]

There is no such thing as an adjustment valve for the pump's pressure. The pump delivers a flow and the max pressure is determined by the OPV setting. You can think of it as a maximum pressure limiter.

In any case, I'm glad to hear you found the source of the problem. That's the first vibe pump I ever heard of going bad so it will be interesting to see if others eventually show up as well. Let's hope not!

You should try opening the old pump to see if you can find the cause of the problem. Pretty easy actually. It's interesting to see the simple mechanism and the tiny plastic check valve.

Well, I guess we'll call it semantics, but I meant the same as you said. We'll call it line pressure instead. As far as the old pump, I did try to take it apart. Took most of it out except for the little plastic part inside the copper end of the pump. I could not get it out without breaking it, which would defeat the purpose altogether. Of what I did see, there was nothing broken, bent, or occluded. So, it is a mystery tome still as why why it failed. The guys at Chris said that although they don't fail frequently and should/do work for years problem free, they have seen a few in different machines. I am sure the number of people that buy these machines and use them for home us is huge compared to the ones that are members in online forums. I suspect that may be a reason.

Thanks again for all the replies and efforts. It did help me quite a bit.

[scareyourpassenger]

Looks like my Mini has started to act up. Time to pull the filter just in case and take it from there. 12months on it so far..

[Endo]

I gave up on the reservoir filters a few months back. I pulled off everything and now run with no filter restrictions (nothing to get blocked and easiest on the pump).

I started using this cheaper filter/softener system called the BWT that is made for coffee machines. The filter costs only $10 and I like the water taste better as well (it uses magnesium ion exchange rather than sodium which I find changes the taste slightly IMO):

http://www.espressoplanet.com/coffee-an ... tcher.html

[scareyourpassenger]

Filter was the issue. I use filtered water only when filling it so I was a bit surprised that it would need changing when it did.

[Johnlyn]

I gave up on the reservoir filters a few months back. I pulled off everything and now run with no filter restrictions (nothing to get blocked and easiest on the pump).

I started using this cheaper filter/softener system called the BWT that is made for coffee machines. The filter costs only $10 and I like the water taste better as well (it uses magnesium ion exchange rather than sodium which I find changes the taste slightly IMO):

http://www.espressoplanet.com/coffee-an ... tcher.html

No use of the in tank filters eh?? what are other people doing?

I see the sense in it to avoid clogging but I want to prevent the buildup of scale as much as possible. my well water is softened and then goes through an RO but the taste is so so. I get local RO water from town and it actually tastes great. I have been using that straight. it is just below 30 PPM, i don't mix with hard water and the low water sensor still works. I've read a lot of conflicting statements and am still figure out the best solution. With the water I am using I feel that I am possibly sacrificing a tiny amount of flavour for the advantage of limiting scale buildup. are the in tank filters just overkill and maybe I can save the bucks? (that I am spending on water?)

[Endo]

If your water is 30 ppm, you certainly don't need the reservoir softener.

[Johnlyn]

If your water is 30 ppm, you certainly don't need the reservoir softener.

Interesting! thanks Endo, makes sense. I really don't want to deal with scale buildup in the steam boiler...

[scareyourpassenger]

It looks like I may need to remove the tubing if I am going to run without a tank filter. It got low enough to cause water pressure issues but not low enough to trigger the water light. At least I think that is why the pump bogged down to 3-4 psi max pressure.

[Endo]

I removed the tubing as well. Inlet sit below the float sensor so the "empty" light comes on before the pump runs dry.

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[southpaw]

Had a similar problem with my machine tonight. Thought I'd remove the tank filter before taking apart and it's cured :)
Having read all the above it does seem likely there is another cause that may cause it to reappear.

[southpaw]

2 days later its returned :( I tried a descale to see if that would help and it did until I did a backflush and then the problem returned.