La Marzocco GS3 leak - steam boiler fitting

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
mixedup
Posts: 139
Joined: 15 years ago

#1: Post by mixedup »

Just got my machine back from service (pump issue) and was very excited to get back to espresso....fired it up and heard an odd noise when the boiler pressure started building. Turns out, water was dripping from the fitting shown in the photo. Needless to say, I immediately shut the machine down.



Any thoughts? Should I try and tighten one/both of the nuts?

tr182md
Posts: 74
Joined: 9 years ago

#2: Post by tr182md »

That is disappointing, I would let the shop know that they missed that. It probably just needs to be tightened but it is too bad they missed it on bench testing. Looking at the parts manual I am trying to figure out which connector that is. It looks like either hot water or steam connector depending on which side of boiler it is.

If it were me and I were not taking it back, I would loosen it, check to make sure it is clean and not cross threaded. Then I would tighten it gently and turn it on again. With some of those types of fittings they often need a final tightening. The only reason I would take it apart is because I don't trust anyone else and I did not assemble it. Compression fittings don't need teflon, pipe fittings do. If it is a compression fitting there is compression ring that could be missing. But I doubt it. That would be too sloppy.

I think it is a compression fitting so it probably just needs a slight tighten.

http://www.globalspec.com/ImageReposito ... 95b171.png

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AssafL
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#3: Post by AssafL »

It is near the vacuum breaker so I think is the OPV connection.
Scraping away (slowly) at the tyranny of biases and dogma.

mixedup (original poster)
Posts: 139
Joined: 15 years ago

#4: Post by mixedup (original poster) »

He didn't do any work on that side of the machine -- guessing it worked it's way loose on the drive home (it was the nut on the line that was loose). Tightened and all seems to be ok, but I want to let it cool down completely and then fire it up again tomorrow just to double check.

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Peppersass
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#5: Post by Peppersass »

Assaf is correct. The tube leads to the OPV in the center of the machine.

If your dealer was only working on the pump, I would guess that the nut or fitting came loose during transport. It happens. But just in case you might want to call your dealer and ask if they removed any of the fittings on the steam boiler.

It's not a compression fitting. I don't know what they call this type of fitting, but there's a semi-spherical "pipe cap" soldered into the end of the tube that mates with the 1/4" M/M BSPP fitting on the boiler. There's no compression ring or gasket, and it shouldn't be necessary (or helpful) to use Teflon tape on the threads. The pipe cap is supposed to seal the opening in the fitting completely. There are quite a few fittings like this in the GS/3.

The nut on the tube probably just needs snugging, but I agree that it's best to turn off the machine, let it cool completely, then unscrew the nut and gently pull the tube away from the fitting to make sure there's no debris preventing a tight seal and that the nut wasn't cross-threaded. Then snug it up (not too much force!) and turn the machine back on. If you still hear hissing, try ever-so-gently tightening the nut.

If that doesn't work, try snugging the fitting -- again, ever-so-gently. If that doesn't work, the fitting has a copper washer at the bottom that might need to be replaced.

Here's how I like to tighten nuts and fittings when I don't have a torque spec: Hold the wrench loosely with your fingers and turn the nut slowly. Most of the force should come from your fingers and wrist, with as little force from you arm muscles as possible. You'll notice a gradual increase in resistance, then a sudden jump up in resistance. Sometimes if feels like the nut has bottomed out against a wall. That's usually the place to stop. In many cases if you continue to tighten beyond a quarter turn more you'll strip the nut or fitting.

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AssafL
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#6: Post by AssafL »

I think these are called Brass Nut and Nipple sets and are MAP brazed to copper. They are usually sold for hydraulics and not for regular water lines.

Dick's comments are spot on, but I'll add one thing I found helps. Sometimes, the nipple doesn't sit well against the coupler's flare. It is harder to get a good seal without over tightening the nut. To avoid this close both nuts on both ends of the coupler pipe by hand. As you tighten the nuts, wiggle the assembly. As the nipple aligns with the coupler, it will 'fall in place' and be easier to tighten again. Keep doing this until the nipple sits well in the coupler flare. At this point, usually a bit of tightening is all that is needed to seal.
Scraping away (slowly) at the tyranny of biases and dogma.