La Marzocco GS/3 Part Failure And Minor Maintenance

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by wholemilklatte »

I've had it on my list for a little while to drain my steam boiler. We were away last weekend and i had the machine off so when we returned i figured i'd have at it. Problems ensue :D

I've never used the ball valve - but it was used about 8 months ago when i got the machine (used).
I've been suspicious of the vacuum breaker but there haven't been any problems with it.

When i opened the ball valve nothing happened. Suspecting the boiler was vapor locked due to a bound up vacuum breaker proved correct. I opened the steam valve but condensed water in the wand persisted the vapor lock. Wanting to get this sorted i blew into the steam wand - i know, but it worked perfectly - after clearing the condensed water it drained perfectly.

Done deal, close up the ball valve, fire it up. As the steam boiler came back up to pressure i got a repetitive drip coming from the valve - not from the where the valve fits to the boiler but from the rotating knob on the valve. Game over.

I shut it down and worked the valve a little but it continued to drip when under pressure. Nothing got into the brain box as i had a towel strategically placed the whole time, but i needed to order parts.

Tonight i replaced the ball valve and the vacuum breaker, straight-forward but not easy

Ball Valve:
- it's really difficult to work in there given that there's a wiring bundle running right where the ball valve is preventing it from rotating cleanly. And when the valve leaked it leaked right onto the wire bundle in a spot that's buried in the corner.

Vacuum Breaker:
- replacing the vacuum breaker is pretty simple but the new one didn't fit at the same orientation as the old one meaning i had to screw around with the frame and tubing connected to it.
- once i had it placed as well as i could i brought the machine up to pressure and got a regular drip out of the brand new vacuum breaker. I had to remove it, disassemble it, put teflon tape on the internal threads of it, reassemble and screw around with the frame and orientation again.
- i don't know if that's normal or not but it was a little bit of a surprise. I ordered a few new o-rings for the vacuum breakers so now i have a backup ready to go.

The good news is i'm back up and running with minimal downtime and i got more comfortable working in the machine. I was also pleasantly surprised to find effectively no scale in my 10 year old steam boiler. There's a little bit of crap in there at the bottom but it's pretty clean otherwise.

(the rotation of the pictures doesn't match the way they appear on my phone for some reason)

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#2: Post by AssafL »

The ball valve seems to scrape the Teflon rings which eventually leak. I replaced mine too.
Scraping away (slowly) at the tyranny of biases and dogma.

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#3: Post by Peppersass »

Been there, done that, got the t-shirt (literally -- I have several nice LM t-shirts!)

However, I've never had the vapor lock problem you describe, and actually I'm not sure that's the right term for it. It happened because there wasn't an opening for air to get into the boiler to push the water out the ball valve. Sort of like what used to happen with beer cans when you punched a hole in one side of the top with a "church key" style opener but didn't put a hole on the opposite side. No joy. (Actually, you may be too young to remember beer cans that didn't have pop tabs :D .) Anyway, you solved the problem.

The ball valve is not a high-quality part, which is unusual for the GS/3. Mine failed in the same way as yours after about seven years of not being used all that much. However, pretty sure I hastened its death by accidentally pushing on the lever while working in the machine, which exposed the lever seal to the full pressure of the boiler (the brass cap was in place.) That seal is not designed to withstand any pressure at all. The ball does that. I believe there's an o-ring or plastic gasket that seals the lever, and the pressure weakened the seal.

It didn't fail right away. I think it started slowly dripping over a period of months. Eventually, some of the water dripped down into the brain box and I got some funky symptoms due to water contamination on the logic board. Luckily, I recognized the symptoms (don't ask my how, it's a long story), got in there and dried off the board before it was permanently damaged. When I replaced the valve I took the opportunity to seal a couple of unused holes in the chassis that happen to be very close to the ball valve and right above the brain box. Water probably wicks down the wire bundle, too.

Which brings me to some questions: Are you sure that the valve only started leaking when you operated it this time? Could it have been dripping before that? How much water did you see drip out and could any of it have gotten into the brain box?

If I were you, in an abundance of caution, I would open the brain box, remove the logic board and make sure there's been no water contamination.

If you feel that this isn't necessary, then I suggest you keep an eye out for any unusual behavior, like display glitches, buttons not operating, time clock not remembering the time after a power down, etc. If you see anything that's not normal, even it's it's a one-time glitch, open the brain box and inspect the logic board. Usually it can be dried and restored to normal. If you let it go, the board could be permanently damaged and it's very expensive to replace.

On the vacuum breaker, it leaked because there should be a copper washer between the valve and the elbow fitting. BSPP fittings require a washer to seal correctly. Didn't you get one with the valve assembly? Teflon tape is OK -- I sealed my level probe with it when I didn't have the replacement fiber washer on hand -- but you might want to replace the tape with a copper washer next time you service the valve.

Oh, and yeah, it's really hard to get the orientation of the valve right. I have a couple of valves and I think three of the elbows, and I've not been able to find a combination of parts that always screws tight in the right orientation, which is vertical with the spout level and facing left over the boiler (the valve needs to be vertical so the plunger drops down and opens the valve when the boiler cools.) I'm not sure if the orientation problem is because the copper washer thickness changes every time the assembly is tightened or if the threading is compressing or what. Drives me crazy every time, but after lots of trial and error I eventually get it into the right orientation.

wholemilklatte (original poster)

#4: Post by wholemilklatte (original poster) »

I check under the covers every month or so and I've never found any evidence of a leaks (at the ball valve or anywhere else). I wanted to get in the habit of cycling the water in the steam boiler every few months as it sounds like generally good practice but i'd been putting it off.

Since i'd never used the valve before i took some time to move the wiring around enough to get a towel in there and kept a close eye on it while i was working on it. The towel and wire conduit material (the wiring goes into some sort of PVC bundle/conduit right there) got a little wet, but there was no standing water. I dried it up and pulled the brainbox out - none made it onto the solid top of it so i felt fine with it.

When i turned the machine back on and brought it to pressure i was watching it closely. As it came up to pressure water started leaking from the screw area where the ball valve lever connects. It was a very small amount that i also caught with the towel and immediately turned off the machine, unplugged, reinspected etc.

After reinstallation of the new ball valve, cap and BSP+1/4" fitting i've had no further leaks (I checked it as it came up to pressure and then a bunch of time over 12 hours or so. It's been at pressure for about 24 hours now.

With the vacuum breaker i think i got a bum one. It didn't start until it got pretty close to 1.5BAR and the slow leak was coming from the joint in the vacuum breaker itself. After a couple of tries tightening it i disassembled it and put tape on the joint. That seems to have solved it. When I disassembled it i noticed it had a rough thread, as if there was a burr in there that during assembly. At any rate, it's good for now but i'll probably swap it the next time i'm in there and try to get the orientation back to something more ideal.

I pulled the top off of the OPV can while i was in there and noticed some moisture in the can. Given that it's about 11 years old i'm going to order a replacement for it and swap it out whenever it arrives, i'll probably revisit the vacuum breaker then too.

Sorry for the crappy pictures, i tried to illustrate where the leaks were coming from.

@peppersass, how did you cover the holes in the frame? I was going to plug them with silicone while i was in there but decided not to do it right away and figure out maybe a better way, especially given the heat and proximity to the wiring and boiler.

also do you use any thread sealer, or just the copper compression washers (and tape as an exception)? I asked LM about proper torque using those crush washers and they just said there isn't a recommendation there - just hand tight + 1/4 turn. That seemed to work fine, i don't want to mess up the boiler.

wholemilklatte (original poster)

#5: Post by wholemilklatte (original poster) »

I was looking at the failed ball valve tonight and it looks like on the side facing the boiler (the side that's saturated ~100% of the time) there's a copper insert that holds the teflon/plastic/whatever bushing in place against the ball valve. The copper insert is an 8mm hex insert of some sort.

The extra surface area of the hex shape lets things adhere to it much more easily than the smooth rounded surface on the exterior side of the valve.

So i figured i'd disassemble it. I wasn't sure about the 8mm hex screw but after working it in there for a few seconds to break up the deposits it was a perfect fit. I held the body of the valve with a 12" crescent wrench and used a 12" 8mm hex key for the insert. It should come apart peacefully right?

The copper rounded off with little flakes of metal flying everywhere - and i opened up my knuckle

You can see small scrapes in the plastic bushing though, i think @AssafL nailed it - and kept his knuckles intact too i bet :mrgreen:

wholemilklatte (original poster)

#6: Post by wholemilklatte (original poster) »

One more addition to make to this post:

I spoke with someone at La Marzocco who mentioned to me that they recommend replacing the steam boiler over pressure valve (OPV) annually. This seems like overkill to me given it's a machine for personal use. They agreed and said i could certainly extend the period but their official recommendation is for annual replacement.

Since i was intending to get a set of preventative maintenance done (and my machine is ~11 years old and still using the original OPV) i figured it made sense to replace it. It's definitely more of a pain than the other parts mostly due to the fact that you need a large deep socket and would do well to use a vice and a long/heavy wrench to get it locked down properly. I don't have a vice and i don't have a proper long wench - but i made it work (and only opened up one more knuckle in the process. :mrgreen: )

That said, removing the OPV is easy, you kind of want the vacuum breaker out of the way first, which means pulling the sides, top, and rear panels - so doing all of it at once would have been easier. Best bet is to remove the OPV by removing the copper pipe it's attached to from the boiler, snake the assembly out of the machine, and work on it on your bench. Replace everything, bring the machine to pressure and look for any leaks.

After removing my old OPV i have a feeling it's totally fine, there doesn't appear to be any scale built up on it, it looks exactly like the new one just not as shiny. I doubt the attributes of the spring has changed in any discernible way and as far as i can tell there's no gasket involved (but i may be wrong about that).

Something i noticed though:
- My vacuum breaker setup uses a tee to connect the vacuum breaker and OPV via silicone hose to a hole above the drain pan.
- It's an older machine with an updated vacuum breaker setup.
- When the machine is coming up to pressure the steam from the vacuum breaker goes into the can the OPV sits in (as well as out to the drainpan) this leaves moisture in the OPV can where there otherwise wouldn't be any. There was a small amount of discoloration around the base of my OPV which i'm sure is due to this.
- Newer machines have a separate hose connection directly attached to the drain pan for the OPV and another for the vacuum breaker
- This requires a additional hole to be cut in the chassis for the mount.
- It has to be a better (safer) setup though.
- I can't imagine what happens in there when the OPV is actually activated but i'd be surprised if it didn't blow the tube off the vacuum breaker and spray down the inside of the machine.


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#7: Post by Peppersass »

I just went through exactly the same procedure with my almost 9-year old GS/3, replacing the original OPV just in case.

I've also done the vacuum breaker mod and have the same issue with water/condensation from the vacuum breaker getting into the OPV can. Not a big deal, but would be nice if it didn't happen.

I've had the OPV go off once or twice (maybe thrice) when I had steam boiler overfills due to water contamination on the logic board. But that's a much longer story. However, that was before I did the vacuum breaker mod. You may be right about the force of the OPV blowing the tubes off. Never considered that.

Are you using the plastic tee that came with the vacuum breaker upgrade kit? I'm not. I substituted a metal tee. Perhaps that will hold onto the tubing in the event the OPV triggers. I think the metal tee might hold onto the tubes better, and it's less likely to be blown apart like the plastic tee.

It's certainly unlikely that the OPV will trigger, but it might be worth drilling an extra hole in the chassis and installing a separate fitting for the vacuum breaker tube.


#8: Post by chrisvarghese »

Just a quick noobie question, is the OPV the same as the Expansion Valve, is it the one located vertically above the rear right of the drip tray?

I'm wanting to do my 1 year maintenance, and was planning on changing the Vac Breaker (L19301) and the Expansion valve (T2104) but may rethink on the expansion valve if it causes too many issues and the existing one hasn't failed.

wholemilklatte (original poster)

#9: Post by wholemilklatte (original poster) »

The expansion valve controls over pressure for the coffee boiler - and is the one you're talking about, it's a brass piece connected to a copper pipe and exits on the right side of the drip plate. It tends to be configured to allow water to exit at ~12bar of pressure although it may drip occasionally, especially as the boiler is coming up to pressure.

I don't think it needs to be replaced unless you're having a problem with it. I also picked up a new one for my machine but haven't replaced it as the one on the machine now works perfectly. Having one on hand is nice through so that in the event of a problem i won't have any downtime in the future.

The OPV on the steam boiler (which is what we were talking about) is located inside of the machine. It actually sits in a small metal can and is connected to the steam boiler by a short length of copper pipe. It sits sort of above the motor and in between the two boilers. My motor is external to the machine so it's easier to access but in general to get to it you'd need to pull at least the right side panel, the top panel and probably the back of the machine.

You could try draining the coffee boiler and see if your expansion valve needs replacing as part of that - although i'd doubt it. I think it's good practice to drain the coffee boiler periodically (i don't know the right frequency or how important it is). LM recommended to me to drain the steam boiler every 3 months. The steam boiler is a difference situation from the coffee boiler due to the potential for the buildup of scale, and increasing concentration of minerals in the water that's present. The coffee boiler is fully saturated so you don't have that same problem.

I drained my steam boiler last weekend for the first time after replacing my ball valve and it's super easy when everything's working properly (go figure :D )

Once the machine cooled sufficiently i pulled the left side, removed the cap from the ball valve, hooked up a hose routed into the sink, and opened the ball valve. ~30 seconds later the boiler was empty, i rocked the machine a little to get the last of the water, closed the valve, put the cap back on and powered it up. If you ignore the cooling and heating cycle the whole thing takes maybe 5 minutes. If the ball valve fails like mine did, it took 4 days and priority shipping ;)

wholemilklatte (original poster)

#10: Post by wholemilklatte (original poster) »

@peppersass, i've got a metal barbed T in place in mine, it holds the hose really well, the egress tube on the OPV can is smooth but it a bit larger than the barbed fitting - and it seems pretty tight. My vacuum breaker fitting is smooth and tends to be pretty easy to be removed, i have a feeling that's the one that would go.

the OPV probably wouldn't overpower the vacuum breaker and the hose would pop off right there.

I'm curious, my understanding is that the OPV activates at or around 2.5 bar, knowing how much steam comes out my steam wand at ~1.5bar and the fact that the OPV appears to be designed to vent a significantly larger volume of steam what actually happens, it is a minor escapement just until pressure falls a little, or does it open up and vent a significant amount of moisture?