La Marzocco GS3 - Leak at Swivel Fitting in Steam Assembly Elbow

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

#1: Post by blacktalon »

Hi all, it's been a while since I participated, although I still stop in regularly to read and get some info on minor fixes. First the ramblings/ background:

Seems like I'm on a reliable 6-1/2 year schedule for having my machine (one of the 'fire sale') disassembled and scattered around for the better part of a month. The machine gets home use only, for 2-3 cappuccinos/ day plus a steamed milk here and there for others to pour into their pod machine coffees. it is not plumbed; I fill the reservoir using water from a Brita, and I manually dump the contents of the drip tray into the adjacent sink.

The coffee boiler started losing pressure (going down to 0) and a steady drip developed out of the expansion valve. There also was a steam/ water leak at the wand assembly.

The steam leak looked easy enough, as it appeared to be at a fitting that needed to come apart anyway so I could replace a worn spring in the lever assembly. So that all was taken apart, cleaned, new spring installed and reassembled. No more slight leak at the fitting, so that side of the machine all looked good.

Pulled the water line assembly out of the group head, removed more corrosion due to the chromed brass (did a bit of this last year as well), replaced the gaskets, etc., and all of that went back together with no issues.

Now with the sides fully exposed, there were a few fitting at the boiler on the right side that appeared to be leaking, as there were some small mineral deposits. And a spot below the end cap. I had reworked all the connections on the steam side 6-1/2 years ago, and that side still looks good. But at that time the right side fittings did not appear to be leaking so I did not do anything other than snug a few fasteners. So this time I pulled all the connections, cleaned scale of the element, filed down the rough edges of the threaded holes and replaced all the gaskets. There was a lone connection at one of the brass 'blocks' that had obviously leaked slightly, but I could not get the fitting disconnected and I decided to leave it (starting rounding the brass fitting trying to loosen). I pulled apart the vacuum breaker (which I 'updated 2-3 years ago), cleaned and replaced the gaskets, and then cracked the dang plastic housing by overtightening. So an expensive little slip up, as I had to order a new one.

Decided to look in the electrical tray and found a very small puddle of water that was milky. Uh oh... Pulled the board and cleaned around the areas where the water had been, using suitable alcohol (99%?). Put everything back together and fired it all. All was well. For a while :) and then a temp probe error appeared. A little research point back to the board, so I pulled it again and really went to town on it with alcohol and wood toothpicks. Viewing through a magnifying glass I thoroughly attacked any/ all possible spots of very tine mineral deposits or other debris. New result is I put it back together and the machine now heated properly and threw no more errors. In fact, what had been an inconsistent display for the whole life of the board (I installed it 6-1/2 years ago) now illuminated properly, with the LED lines all staying lit rather than some of the segments turning off. So not only fixed, but better than before.

But dang, the fitting I had unsuccessfully tried to remove was now seeping, and I could not get it snugged without pulling off a bunch of stuff. I tabled that work and dug into the expansion valve drips. All signs pointed to a bad OPV, which proved to be accurate. So I ordered a replacement and also ordered a new expansion valve. Even though I thoroughly cleaned and descaled the original one a few weeks ago it did not turn very easily and I believe the rubber pieces inside have probably given more than was every expected.

The new OPV and expansion value arrived a few days ago, along with a new set of flare wrenches. I pulled everything apart that needed to be removed in order to clean up and reseal the one troublesome fitting. The flare wrenches did not help much because they are too thick, and of course they are 6-point so it's 60 degrees between positions -- which is largely unusable with a lot of other plumbing in place. I pulled the OPV container box and plumbing, and cleaned as well as I could. There was a little rust deposit, as it looks like the welded connection for the drain line is mild steel... But the new OPV went in with no issues and the old one was definitely stuck open. I'm saving it in case it is repairable, although I could not find any threads about disassembling and refreshing. It seemed like replacement was the typical solution for the rare occasions when there is an OPV issue.

I put it all the plumbing back together and turned it back on. Steam pressure built and was steady in a good range. And lo and behold, after bleeding the group head a couple times, brew boiler pressure seems to be normal. I adjusted the new expansion valve until the gauge pegs right at 12 ATM when pulling a shot, and pressure does not slowly drop all the way back to 0 anymore.

I put front and back panels on, made sure the electronics tray was fully buttoned up/ screwed closed. All was good, and life was good. Until I did a test of the steam wand. Which resulted in a small cloud of steam and a little bit of water. Tried it again while watching closer, and the leakage was at the push-on 90 deg elbow w swivel fitting that connected to the steam valve assembly.

I will admit I have no experience with push-on fittings, so it took me a few minutes of internet research to see how easy it was to remove the teflon tube. So I pulled the fitting and the tube, pulled out the collet, replaced the internal gasket, reset the collect, pushed the tube back in and reconnected to the steam valve. A quick pull down on the steam lever showed my work was for nothing.

The leak is at the 'swivel' -- where the end fitting is mechanically secured to the cast body of the elbow. There appears to be a thin metal washer, but I'm sure internally there is something going in with a metal-to-metal seal or a rubber gasket that cannot be accessed.

Has anyone successfully pulled apart and resealed one of the elbows at the swivel connection? I searched and searched earlier this afternoon and this evening, starting with H-B then Google in general, and also YouTube. I watched a dozen or so YouTube videos about push-on fitting leaks, but none addressed the leak point I am experiencing.

I'll order a new elbow tonight, but it's another week before I'll have the part in-hand. Maybe longer, as Espresso Parts indicates it's a special order item. I rigged a temporary catchment/ gutter system with foil-faced tape that seems to do a good job containing the escaping steam and discharging the condensate into a measuring cup on the counter, but it is a bit more water than I am comfortable with so I may skip the milk this week. As a consolation prize I seem to be back to proper brewing operation so I will at least be free from the horrid pod machine.

Thanks for listening. Any info on the repairability of the swivel in the elbow is much appreciated.


#2: Post by newmanium »

Another thought is to upgrade to the new metal steam connection rather than the Teflon tube. I did this when I moved to the full-burn wand and it's been pretty solid. If you do the new pro steam wand, this is also upgraded I believe as part of that kit.

blacktalon (original poster)

#3: Post by blacktalon (original poster) replying to newmanium »

Thanks. I'll look into it.