La Marzocco GS3 Maintenance, Issues, and Upgrades

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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#1: Post by Milligan »

I bought a used GS3 a few months ago and have been enjoying it. I immediately had to replace the portafilter gasket because it was hard and cracked. I used the Cafelet Silicone gasket and its been great. I figured I'd need to replace some more things due to the neglect of that seal. I had to readjust the brew boiler pressure valve and adjust the pump a bit. Not too bad.

Over the last few weeks my steam seems to be different. I used to get decent microfoam (not excellent, but serviceable) but have been struggling with either too many large bubbles or not enough rolling action to texture. Its been a struggle to find a middle ground of nice tight stretching and rolling for texture. I had to up the pressure to right at 2bar to get a good rolling action in only 6oz of milk. I spent 2-3 hours practicing with no real progress. It makes no sense compared to other videos of a GS3 getting massive pressure/power (at the tip, not just indicated.) I decided to see how long it takes to heat 6oz of milk at 1.8-2bar to 150F and it was 37s. Far longer than other videos show. In particular, the HB latte art video shows them stretching and texturing from start to finish in 20s and they seem to be doing a larger quantity with a lower steam pressure. Other videos are similar. I found that the wand got too hot to touch so I figured I had the burn-me wand. Here is what the wand looks like without the tip (mine has the stock 4 hole tip not sure if it is the L208 or L178.) Not sure what I have...

So I figured it may be the tip I have or something wrong with my valve/steam wand. When I opened up the side I noticed wetness under the OPV valve cup for the steam boiler. It was dripping out even though the pressure was nowhere near 2.5bar. I decided to shut down the machine and investigate. I first pulled the vacuum breaker and it was in rough shape. The O-Ring is brittle and cracked. The previous owner/service technician left out a copper crush washer on the bottom fitting and instead used something like pipe dope.

I removed the steam boiler OPV and cup from the machine. The cup wasn't sealing to the OPV well and allowed water to drip out. Upon inspection, the valve has been leaky for sometime. It has what appears to be a thin coating of scale. The OPV was extremely tight to the fitting on the bottom, nearly seized. I had to go to my shop and use a 24mm deep socket on the OPV and put the fitting in my vise then cranked on it with way too much force to break it free. Perhaps it leaked for the previous owner and they over tightened it to try to fix the issue. I'm afraid the flare may be grooved now.

I figured the OPV was toast so I decided to open the cap on the top (which I assume is calibrated from the factory for 2.5bar.) The spring and arm came out but the seal was frozen. I had to tap it out to dislodge it. I'm guess the seal piston was frozen slightly open allowing pressure to escape.

So far it looks like I'm going to need a new steam boiler OPV, a new vacuum breaker, and possibly a new OPV copper line. I may go ahead and upgrade to the latest version of the vac breaker.

Is there anything else you guys would recommend I check for before ordering parts? I want to make sure I don't have a cascade of issues and would rather deal with obvious stuff all at once. The hand operated steam valve has been replaced by the previous owner. I took it apart and it looks brand new. I haven't noticed any scale in the copper tubes I've taken apart so that is good but it makes me want to take a peek instead in the boilers. But I don't really want to go messing with things if I don't have to.

Thanks for any tips!

Milligan (original poster)
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#2: Post by Milligan (original poster) »

I ordered a vacuum breaker rebuild kit from Clive Coffee instead of spending the $100 on a newer design. I got the OPV from Voltage Supply. Luckily everything is in stock so maybe I'll be up and running again next week. I also ordered a few copper crush rings and a smaller orifice LM tip.

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#3: Post by danetrainer »

Is there anything else you guys would recommend I check for before ordering parts?
By the looks of your other items I would inspect the 1-way valves on the right hand side of the machine, if you have the AV model I believe there are 5 of them. Search for the topic from Jake when he did a full rebuild of his machine to learn more. And of course LM is seriously overpriced for the replacement ones.

Milligan (original poster)
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#4: Post by Milligan (original poster) »

While I wait for the parts to come in, I decided to go ahead and start on the upgrades I've been wanting to do since the machine is down anyway. I've been planning a Jake valve set up but wanted the knob to be accessible through the side panel via a knob or lever. This meant making custom side panels. Unfortunately, I was a bit hasty choosing parts for my first attempt at the Jake mod and purchased a valve that did not work that well. The working range was too near the closure point of the valve causing pressure fluctuations.

Although the valve didn't work, I really liked using the copper tubing and compression fittings. The reason for going with hard tubing is so the valve is supported via the copper pipe so I can turn it without it having to be attached to the side panel. If I had used hose then I'd have to fabricate a bracket somehow. Eventually I will likely fabricate anyway.

My idea is to have the valve poke through the side panel and be worked via a wooden knob or lever (or perhaps a turned piece of metal depending on how the project goes.) So the next step was to make some side panels. There was no way I was going to spend $700+ on LM panels only to drill a big hole in it for the knob so I decided to make my own. I used cheap pine to make mock-up panels to get everything fitted the way I want and then I will remake them in walnut. I finished the mock-up pine panels today and like how they came out. The panels were made from a 5/8" edge glued pine board costing $7.

Mock-up panels from pine

I traced the original plastic panels. Then jigsawed them out leaving about 1/8" away from the tracing. I screwed the LM plastic panels to the cut pieces and used a router pattern bit to shape them to the stock size. I then did another pass with a curved router bit on the front and back to smooth the edge. I drilled the mounting holes and plunge routed the inset for the thumb screws. Now that I have the process down and like the results I will start looking for some clear walnut.

Lastly regarding the modifications, the chrome has seen its fair share of use so I'm thinking I may have the panels powder coated at a local shop. Not sure what color I'd go with yet.

Also, I don't feel so crazy about the milk steaming issue anymore. I went to my mom's house today and made a few drinks with her Breville Barista Express. On the very first pitcher I steamed, it was better than anything I've gotten out of the GS3 likely ever.... It was effortlessly easy to stretch and roll. It came out velvety like marshmallow and laid beautifully as latte art. Night and day difference. So there is definitely something weird happening with my steam setup on the GS3. I spent days and eventually 3 hours straight trying to get something excellent out of it with no progress. Meanwhile I step up to a $500 machine and made high-end cafe quality latte art steamed milk on my first try... Hmmmm.... and then another...

Milligan (original poster)
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#5: Post by Milligan (original poster) »

danetrainer wrote:By the looks of your other items I would inspect the 1-way valves on the right hand side of the machine, if you have the AV model I believe there are 5 of them. Search for the topic from Jake when he did a full rebuild of his machine to learn more. And of course LM is seriously overpriced for the replacement ones.
Thanks for the tip, I'll check those out and Jake's thread.

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#6: Post by danetrainer »

Geez, I really love the look of your Pine panels, although I did grow up in a home with Pine cupboards and trim work! Nice work on those too, I would think with a black stain and satin finish, then powder coat your trim in black the machine would look awesome. I've had both Walnut and Glass panels on mine, but I no longer have a gs3.

Milligan (original poster)
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#7: Post by Milligan (original poster) replying to danetrainer »

Thanks! I think they turned out great for mockups. I would have been pickier with the grain selection had I known they'd look so nice on the first attempt. The other side is clear but there is one knot on the visible side. I'm kind of a sucker for lighter wood tones like maple and white pine, but unfortunately this pine is too soft for a long term selection. Even small bumps leave indentations. I also grew up in a house with a lot of pine woodwork. It was all heart pine flooring and cabinetry. My mom still lives there so I get to continue enjoying it when I visit.

I used to do a lot of wood work for picture framing and did quite a bit of carpentry on the side when I was younger. I never worked much with harder woods so it will be a fun project for me. My father-in-law has a wood lathe so I plan to turn some knobs and a cap out of matching wood in the future.

I'm thinking I'll keep the top tray and the drip tray chrome and do satin black on the metal panels. We will see as it evolves! I also like your idea of "murdering" out the machine and leaving a few bright pieces and chrome. Lots of potential.

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#8: Post by ira »

As I look at what you're doing, I keep thinking it would be really cool looking if the knob was made out of the same wood and a couple of inches in diameter set flush with a shallow depression to turn it. Just doesn't seem like a knob sticking out the side is right on that machine. Just a silly thought to make the job even harder than you planned.

Milligan (original poster)
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#9: Post by Milligan (original poster) replying to ira »

Yes I can see that. Make it less obvious. My original idea was to have a small lever so that I would get to know where along its throw different pressures would be. Like a slow flow for preinfusion then increase to a certain bar before backing off at the end of the shot. A lever would feel more natural for that type of control. Not sure how it will manifest yet. One thing I realize is that a needle valve is flow control, not a pressure regulator. So as the puck loses mass and the flow is the same then the pressure will drop. I figure I'll be making several adjustments throughout the shot.

Milligan (original poster)
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#10: Post by Milligan (original poster) »

I'm still waiting on a few parts for the OPV but I was able to replace the internal of the vacuum breaker and I got my Jake valve installed.

The copper tubing holds the valve in plenty strong enough to work the knob with ease. I spent a bit of time at the hardware store with the valve and believe I've come up with a good way to extend the knob through the side panel to attach to some sort of larger knob. They have brass bushings/spacers that will likely press on nicely. They have tapered plugs that look nice as well for the lever.

Hopefully everything comes in this week so I can get it back up and running.