Hey guys, I've been putting off replacing the o-rings for way too long and finally got around to it today. (1st time they've been replaced and the machine is 3 years old....I'm a lazy idiot!) I'm at the stage where I removed the brew-cap and theres a good amount of scale as seen in the photo.
I've read you shouldn't descale the machine, but WTF! I bought it used from a woman who said she only used Brita water in it for its 1st year (which is sh** filtration), but for the next year I used strictly store bought bottled water and last year installed an under-counter "Perfect Water" filtration system so I figured I wouldn't be seeing so much scale!
How should I clean this? I'm scared now that theres a bunch of scale buildup elsewhere in the machine. What else should I check? If you're not supposed descale the machine, I'm at a loss as to how to keep it clean?


Thanks for reading and any advice that can be offered.

No telling how long that stuff has been in there and what water composition caused it.

It looks suspiciously like the green "verdigris" some of us found in a particular run of volumetric GS/3s made back in the 2009 time frame. See this really long thread to learn way more than you want to know about verdigris. We never found out exactly what caused the problem. Could have been some kind of reaction between dissimilar metals in the presence of a particular water composition.

The problem was quite rare and has only been reported for an isolated group of machines. I don't think your problem is necessarily the same, but it does look like copper oxide has mixed with scale to form a substance similar to the green verdigris. I would check the underside of the group cap and make sure the plating is intact.

There are endless debates on whether to descale or not. Some might say you should descale because you don't know whether there's scale built up in other hidden parts of the machine. Some (like me) feel that descaling may lead to more problems than it solves. For example, large bits of scale breaking off and lodging where you don't want them, or corrosion caused by descaling solution that's too strong. My preference is to soften the water enough so that scale doesn't form -- say, 70 ppm hardness or below (also depends on alkalinity, but that's a longer discussion.)

But that won't help you with the present problem. I think you have three choices:

1. Have the machine professionally cleaned and descaled by a shop that services GS/3s, or at least other high-end espresso machines. They can change your o-rings at the same time.

2. Clean the scale out of the group yourself. You'll have to do some disassembly to change the o-rings anyway, which should help you get at some of the parts. I have the volumetric version so I'm not familiar with how much disassembly you can do on the MP group head. If possible, get all the parts out and soak them in distilled vinegar, then rinse thoroughly with water. After that, disconnect as many of the fittings connected to the coffee boiler as you can and check for scale. Clean as necessary. Drain the steam boiler and do the same. If you find loads of scale buildup, consider #1 above.

3. Descale the machine. In the six years since my GS/3 was new I've never descaled, so I can't tell you how to do it.

Going forward, you need to know the hardness and alkalinity of your tap water and the water produced by your Perfect Water filtration system. I hope you're not using pure RO, because that can be acidic enough to damage espresso machines. Hopefully, you're using a system that lets you add back minerals to get water that's alkaline.

In any case, test your water. If you don't have a water test kit, you should get one.

If you haven't done so already, read Jim Schulman's Insanely Long Water FAQ.

If I remember right, the main verdigris complaint (which only applied to the early "fire sale" models) was that it was clogging the gicleur. If you are not having a problem with the water flow through the brewhead, I don't think I would worry about it.

I am with Marshall on this. While I don't have that machine, I don't think it looks that bad. There is no way you could have expected no scale buildup.

Thanks for the quick responses guys! According to the serial number it was manufactured in January 2012, so I don't think I have that verdigris issue. I do however live at the base of the Rockies and get what I assume is some pretty hard water....my perfect water system adds minerals back in but I've never tested it. Any cheap/accurate test kits I could order?

I scrubbed off what scale I could with a soft pad and literally sucked the big chunks out of the brewhead with a straw (wife says I'm nuts, but didn't want one of those chunks clogging a line.) Next time I'm in there, I'll be sure to do a vinegar soak. Can I use just basic white vinegar from the super market?

On a different note, I changed out all the o-rings. The most 'baked' and crumbly was that orange fiber gasket under the group cap (I had to break it off in pieces) and then the ones in the middle of the shaft were kind of crunchy (one to the point where it crumbled too) I used a dental explorer tool to remove the ones in the shaft and it worked great.....the whole thing putting me off from changing them was the fear of opening it up and then needing to order and wait for that silly $100 LM tool.

After getting everything back on, the grouphead leaked when I fired it up so I've taken everything back apart and now just had a slight dribble from that copper cap on one corner. Now that the machine is hot there's no leakage, but should I be concerned that it leaked on initial startup or now that its heated up once will the o-rings form a tighter seal?f


Thanks again guys, love this community!

CelliniEVO wrote:Any cheap/accurate test kits I could order?

Below are some links to testing kits/strips. Once you know the values you can predict scale accumulation. The scale you had could have all been there since you purchased the machine. Now that you have a baseline, next time you change the seals you'll have a more accurate idea of accumulation.

Hach 5b Test Kit (titration)
Hach 5-in-1 Test Strips
API GH and KH Test Kit (titration)
API PH Test Kit (titration)
API 5-in-1 Test Strips

While you are at it, get a digital TDS meter. Lot of them available on eBay for just a few $$. It will be money well spent.

CelliniEVO wrote:After getting everything back on, the grouphead leaked when I fired it up so I've taken everything back apart and now just had a slight dribble from that copper cap on one corner. Now that the machine is hot there's no leakage, but should I be concerned that it leaked on initial startup or now that its heated up once will the o-rings form a tighter seal?

I would be concerned. The heat will make the seals expand, but they should not leak at all ,whether from a cold start or while up to operating temperature.

Cheers!
Merle

and now just had a slight dribble from that copper cap on one corner.

I ASSUME you are speaking of the copper washer underneath the hex head bleed screw for the group. If so, that copper washer should be replaced any time it is removed.

Sure, copper washers can be reused but the best practice is to replace.

This is the part I'm talking about...guy in the video just calls it a brass cap (it has 4 hex screws and wraps around the bleed screw). I had a very tiny leak coming out under that upper right screw (shown in the upper left of the photo), but once it heated it immediately stopped. I followed this video literally word for word: https://www.youtube.com/watch?v=ZImLqea86Mw Only thing I could think of causing it was uneven tighting of the bolts? The video says to 1st tighten that copper cap "finger tight" and then he tightens the group cap by going back and forth to get an even tightness and then comes back to the brass cap. Could it be possible that I over-torqued one of the bolts and am causing a leak that way?

erics wrote:I ASSUME you are speaking of the copper washer underneath the hex head bleed screw for the group. If so, that copper washer should be replaced any time it is removed.

Sure, copper washers can be reused but the best practice is to replace.

The video of the o-ring replacement didn't have me doing anything to the bleed screw....is there a reason to change it regularly?

The video was focused on one specific task. Any time you "open up" this saturated group, it is recommended that you bleed the group via that particular screw. So, at that point in time, my statement as regards replacing the copper washer applies.

Those copper washers (M6 x 10) are available from any German car dealership and LM still includes a spare or two with new machines.

And now that I see your latest comment, it sure seems as though you took some care. The intent is to ensure that there exists a gap between the brass cap and grouphead and that this gap is relatively uniform (ideally I would omit the word relatively).