New to me La Marzocco GS/3: Steam boiler not heating, odd pump noise - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
daynejones (original poster)

#11: Post by daynejones (original poster) »

OPV looks immaculate so I'm suspecting an overfilled steam boiler. Seems like you have a lot of experience with that one lol.

daynejones (original poster)

#12: Post by daynejones (original poster) »

Update: found a little corrosion on the bottom of the board. There was a puddle of water underneath the steam boiler drain valve and sure enough, looks like some got into the brain box.

daynejones (original poster)

#13: Post by daynejones (original poster) »

Update: after carefully removing the corrosion from the board and re-tightening the drain valve, I reassembled and it's running with no issues but still a small leak at the drain valve (what a pain that it's directly above the brain box). Will keep an eye on things but it looks like the only thing worth replacing now is the drain valve.

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#14: Post by Peppersass »

I think you're spot on with your diagnoses and steps to repair.

Obviously, the ball valve leak caused the logic board contamination, and I'd lay odds that the contamination caused the boiler to overfill. I had a leaky ball valve, described in this post.

The stem failure I experienced was unusual, possibly unique and due to operator error. More commonly, a leak occurs at the boiler end of the valve body where the threads enter the boiler. Sometimes the valve unscrews slightly when the brass cap is removed for draining. You have to use two wrenches to prevent that.

Just tightening the ball valve probably didn't work because the leak allowed some scale buildup on the face of the copper crush washer, the valve, and/or the boiler. Best to drain the boiler, remove the valve, clean it, and clean the boiler hole and the area around the hole. Use a new copper crush washer when reassembling.

If you haven't already, inspect every square millimeter of the logic board for signs of contamination. In my GS/3 AV, there are two small holes in the chassis floor near the ball valve that allow water to leak onto the brain box, where I believe it can enter the box via the screw holes. I plugged those holes with plumber's putty.

On the pump, it looks like the bypass valve broke. There's a piece of a circlip that probably came from it, as well as the black pieces. Seems like an unusual failure.