La Marzocco GS3 MP pump cuts out

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
mgrayson
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#1: Post by mgrayson »

Intermittent, but increasingly frequent problem: While moving the paddle, the pump will sometimes stop (misplaced modifier - sorry). It starts up again with a little jiggling. Sometimes it won't turn on when I start a shot, but again, it starts up after moving the paddle back and forth for a second.

Is this a sign that some contacts need cleaning? Or is it time to do a group rebuild? The machine is about 3 years old and does 4 to 6 shots/day (my wife drinks them, too!).

Thank you much,

Matt

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Jake_G
Team HB

#2: Post by Jake_G »

Hey Matt,

The problem sounds like it is related to the limit switch that the paddle arm presses. I'm not sure if the switch itself can be serviced, but I would start by removing the group cap and seeing if the pump starts reliably when you manually trigger the switch. It could be that the switch itself simply needs to be adjusted to sit a bit closer to the pin on the paddle arm.

Here's a picture of what to expect under the group cap taken from the parts manual:


The pin that actuates the switch is item 12 on the above drawing. As I mentioned, I'd manually trigger the switch and see if you can replicate the problem, and then verify that the pin is threaded securely into the paddle arm and that the switch is securely mounted to the bracket. With luck, all you'll need to do is make sure the switch is tight and sitting low enough to reliably trigger when the pin sweeps under it.

Cheers!

- Jake
LMWDP #704

mgrayson (original poster)
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#3: Post by mgrayson (original poster) »

Thanks, Jake!

I take it the machine should be cold before I remove the pressure gauge :shock: ...

Matt

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Jake_G
Team HB

#4: Post by Jake_G »

The gauge is attached to the group, so as long as the paddle is closed, you can service it safely whilst hot. Just wear some light gloves as it will be "warm". :mrgreen:

You can also reattach the gauge and paddle after removing the group cap and work through any remaining troubleshooting steps before buttoning it all back up.
LMWDP #704

mgrayson (original poster)
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#5: Post by mgrayson (original poster) »

Sorry for my little joke. I should have said "reattach the pressure gauge...". Although it would make a good YouTube video...

mgrayson (original poster)
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#6: Post by mgrayson (original poster) »

I raised the switch very slightly so that it would engage more easily. Everything looks good now, but it is an intermittent problem. We'll see.

I also noticed that one of the wires from the switch had been caught under the plastic cap. It was flattened in two close-by places. I relocated it deeper in its well, but I wonder if there is a possible point of failure there.

Thanks again,

Matt

First test: a delicate layered fruitiness combined with full mouthfeel and ... kidding. It worked fine.

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Jake_G
Team HB

#7: Post by Jake_G »

I hope that worked!

If it still acts up there are a few more troubleshooting steps we can follow.

Cheers!

- Jake
LMWDP #704

mgrayson (original poster)
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#8: Post by mgrayson (original poster) »

Update, which I haven't done since everything works now.

Everything works now. :D

Thank you!

Matt