Recently the steam valve in my GS/3 developed a small leak. For various reasons detailed below, I ended up replacing the entire valve assembly, which costs about $120. The task of replacing the valve was easy, but after disassembling and inspecting the old valve, I'm wondering whether it was necessary to replace the valve rather than simply disassembling and cleaning it.

If other GS/3 owners have had issues with their steam valve, I would appreciate your letting us know what you did to correct the problem: Did you rehab the valve or did you replace it?

Symptoms

The first symptom of the leak was a few drops of water noisily boiling off the tip of the steam wand after use. I had recently replaced an espressoparts 4-hole tip with a Sproline Knife tip, and thought perhaps the internal structure of the tip allowed a bit of water to condense and accumulate inside the tip, which dripped out when steaming was completed. This didn't seem to affect steaming performance at all, so I ignored it.

But as time went on, I noticed more water boiling off the tip for a longer period of time, pehaps ten or twenty seconds. I became suspicious that the steam valve might not be closing all the way, but was managing to seat itself properly after a short time. Since steaming performance was still OK, and the machine didn't leak steam continuously, and steam pressure remained constant, I didn't take action.

Eventually, I noticed small puddles of water under the steam arm when it had been positioned over the counter for some length of time. This had never happened before, and raised my level of suspicion that the steam valve might have a minute leak, even after the bubbling at the tip stopped. Still, it was a minor problem.

Finally, the problem progressed to the point where the tip didn't just bubble after steaming, it emitted a small stream of steam for up to a minute. That would die off eventually and I couldn't feel any steam coming out. But the tip remained hot and the puddles under the tip got larger and larger. At that point, I knew something had to be done soon, or I would end up with a much larger steam leak that wouldn't stop.

Inspection, Research and Decision

I opened the machine to see if the valve might be leaking steam into the interior, but it was not. I decided that I would have to remove the valve, open it up, and clean or replace some of the internal parts.

But when I looked at the parts diagram in the GS/3 parts list, the steam valve was shown as a single assembly, unexploded. There was just one part number for the valve, and none of the internal parts were available. I checked on espressoparts.com, and found only the steam valve assembly, none of the internal parts. I called service at my dealer, Chris Coffee, and they confirmed that no internal parts for the steam valve were available.

I thought the lack of available parts made it risky to disassemble the valve. I thought that if LM didn't supply the parts, it could be because special tools or techniques were required to seal the assembly. I was also concerned that if there was a broken part inside, or if I broke one getting the valve apart, I would be unable to run my machine until a new valve assembly could arrive.

So I decided to buy a new steam valve.

As I said, it was easy to replace the valve. I had already replaced the no-burn arm with the burn-me arm, and also had removed and disassembled the burn me arm to replace the wand portion after the threads at the end of the wand broke off when I torqued a tip on too tightly. In other words, I was very familiar with how to disconnect and remove the steam valve. It took only a few minutes to do the replacement.

Disassembling and Inspecting the Old Valve

Afterwards, I disassembled the old valve. Here's what it looks like inside:



Starting from the right side, when you move the silver ball-lever, it depresses the spacer on top of the spring-loaded brass plunger (the piece with the two o-rings.) The plunger pushes on the spring-loaded valve (the piece between the springs), moving the valve off the seat and creating an opening for steam entering at the fitting on the far left to exit through the threaded fitting on top of the valve assembly (where the steam wand is connected.)

The mechanism seemed to work OK, so my first thought was that the valve or the seat were contaminated and needed to be cleaned. Here's a shot of the valve seat:



And here's a shot of the valve:



They're not pristine, but they don't appear to have any mineral deposits on them. Besides, if dirt or deposits were keeping the valve open, then why did the valve always close after leaking steam for a while? I think if the springs were weak, the leak would have persisted.

I believe the answer might be that the plunger was sticking. Here's a close-up:



There appears to be some grease under the o-rings, so I think they have to be lubricated. It's possible that the contact area of the o-rings has dried out (the right o-ring looks pretty dry), restricting free movement of the plunger and causing it to stop short of losing contact with the valve. Eventually the pressure from the two springs overcomes the stiction, and the plunger comes off the valve, allowing it to seal.

If that's the case, then the o-rings just need to be cleaned (or replaced) and re-lubed.

Conclusion

If my new valve assembly ever fails, I'll try rehabilitating the old valve assembly to see if it can be done. I'll clean all the parts and replace the o-rings if I can find the right ones. In any case, I'll lube the o-rings. But I'm not going to do that now as an academic exercise. I'd rather see if anyone knows whether the valve can be rehabilitated or not.

I'd also like to know why LM doesn't supply internal parts for the steam valve. I don't see any evidence that the steam valve needs special handling to be resealed, though there is a teflon washer on the left-hand fitting. If it was available from LM, I'd replace it as a matter of course.

Any comments?

We had the steam valve serviced in January when it developed the same symptoms. Our invoice from the service tech lists the part "Steam Valve Rebuild Kit B1004 -- $28.04." So I assume that is all that is needed. If it makes any difference, we have the original no-burn wand.

Marshall, I agree, the rebuild kit is what's needed. I've been needing to do mine for a little while now. Also, the no-burn vs. burn-me wand is immaterial for the valve rebuild, because they both use the same valve.

Dick -

When you say "here's a shot of the valve" - it's really the other side that is the valve and that part is a common E-61 valve piece - about a buck or two.

Same goes for the o-rings - after you splurge for the rebuild kit, lets add those o-rings to this list:

O-rings & Copper Sealing Washers

By a strange turn of events we have a brand new GS/3 in our workshop...might take that valve apart to see what is in there. Looks like a pretty standard o ring and flat washer setup.

Marshall wrote:We had the steam valve serviced in January when it developed the same symptoms. Our invoice from the service tech lists the part "Steam Valve Rebuild Kit B1004 -- $28.04." So I assume that is all that is needed. If it makes any difference, we have the original no-burn wand.

The service tech's designation on the invoice was almost correct. The La Marzocco part number "B.1.004" refers, however, to the entire steam valve assembly, such as the one Dick purchased.

For those needing just the GS/3 Steam Valve Rebuild Kit, LM's part number is "B.1.004K" and the list price (as of February 2012) is $29.82.

erics wrote:When you say "here's a shot of the valve" - it's really the other side that is the valve and that part is a common E-61 valve piece - about a buck or two.

So what do you call the piece that I called the valve? Isn't it the case that both pieces together constitute the valve?

The piece I called the valve seat is basically a hole with a raised ring around it, with the ring being the actual valve seat. That's where the "plug" or "stopper" seats to seal the opening. I didn't know what to call the plug or stopper, so I called it the valve. As you can see in the first photo, it has a square shaft on the steam boiler side, which I think in an internal combustion engine you would call the "valve stem".

orphanespresso wrote:By a strange turn of events we have a brand new GS/3 in our workshop...might take that valve apart to see what is in there. Looks like a pretty standard o ring and flat washer setup.

hmmmm why don't strange turns of events happen to me...

So what do you call the piece that I called the valve?

You're correct . . . it is the valve and it would be called a "valve". The other side of the piece has the valve "face" which is replaceable and is the part that does the sealing.



Sometimes those valves come apart easily with a little heat on the "stem" and sometimes not without breakage. The entire part (valve assembly?) is likely contained in the rebuild kit previously mentioned along with the two o-rings which "look like" AS568-105 (nominally 11/32 x 5/32 x 3/32).

Peppersass wrote:If other GS/3 owners have had issues with their steam valve, I would appreciate your letting us know what you did to correct the problem: Did you rehab the valve or did you replace it?

Replaced it with a superior system espresso-machines/la-marzocco-gs3-esteam-t19082.html