La Marzocco GS3 Pump Issue

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

#1: Post by owlbass »

Hello All,

I'm having an issue with my GS3 and was hoping for some advice. I replaced the pump about 6 months ago, but this issue has come back but slightly differently. I have the machine programed to come on before I wake up. About once a week it reads "Boiler Time out Refill" and is cold. This was the same thing that happened when the pump was going bad. Usually turning it off then on again gets it to start heating up the boiler. Twice now when brewing only a small stream of water comes out and pump gauge plummets to zero. I came across a thread with a similar issue with something clogging the gicleur but I don't think that's the issue. La Marzocco home thinks it might be the coil going bad on the boiler 3 way solenoid valve. But seeing how this effects brewing as well I'm not so sure. I'm including a video and any advice would be greatly appreciated. I was thinking of selling the machine and wanted it working perfectly before I do.

Thanks

User avatar
Jake_G
Team HB

#2: Post by Jake_G »

There are two check valves between the pump and the rest of the machine. One is mounted directly to the pump outlet beneath the stainless braided hose and the other is threaded into the tea water mixing valve at the other end of the hose.

I would check both of these for scale buildup as each of these would impact boiler fills and flow while brewing.

Cheers!

- Jake

Weber Workshops: tools for building better coffee
Sponsored by Weber Workshops
owlbass (original poster)

#3: Post by owlbass (original poster) »

Thanks Jake! I actually have a couple extra check valves. The machine is from 2014 so might be a good idea to replace them anyways. I believe I need to drain he boiler to replace these, correct?

User avatar
Jake_G
Team HB

#4: Post by Jake_G »

You should(n't) need to drain the boiler. But the machine needs to be cold and the steam boiler depressurized.

Cheers!

- Jake

owlbass (original poster)

#5: Post by owlbass (original poster) »

Just to be clear did you mean "shouldn't need to drain the boiler".

Thanks!

User avatar
Peppersass
Supporter ❤

#6: Post by Peppersass »

Shouldn't.

There's a third check valve on the flow meter at the back right of the machine. It's harder to get to. If cleaning the other two doesn't solve the problem, you may need to clean that one as well.

User avatar
Peppersass
Supporter ❤

#7: Post by Peppersass »

Re-reading your post, I should add that Jake advised you to clean the check valve at the pump and mixing valve because of the Boiler Refill Timeout. Those two check valves are in the refill path for the steam boiler, the refill of which is timing out, and they're also in the brew water path. So the check valve at the flow meter can't be the sole cause of the problem because it's only in the brew path. But if the other two check valves are scaled, it may be as well. In that case the boiler refill problem would go away but the zero pressure during brew problem would not.

Similarly, given that the problem affects both the steam and brew boiler paths, it's very unlikely the autofill solenoid or 3-way solenoid are the problem unless perhaps both are clogged with scale.

Espresso Vision: the perfect cup of coffee starts with understanding your roast
Sponsored by Espresso Vision
owlbass (original poster)

#8: Post by owlbass (original poster) » replying to Peppersass »


Are you referring the the check valve right before the Tea Water Mixing Valve? Because I think there is also one right after the Tea Water Mixing Valve that then goes to the Steam Boiler fill Solenoid.

Also, now that I think of it the check valve at the pump was replaced 6 months ago when I replaced the pump. But I'll look at it out for scale too.

Thank you!

owlbass (original poster)

#9: Post by owlbass (original poster) »

Now that I think of it the check valve before the Steam Boiler fill solenoid wouldn't have any effect on the brew issue. So I'm guessing the one before the Tea Water Mixing Valve is the most likely culprit. Time to let the machine cool off and dive in.

owlbass (original poster)

#10: Post by owlbass (original poster) »

Peppersass wrote:Re-reading your post, I should add that Jake advised you to clean the check valve at the pump and mixing valve because of the Boiler Refill Timeout. Those two check valves are in the refill path for the steam boiler, the refill of which is timing out, and they're also in the brew water path. So the check valve at the flow meter can't be the sole cause of the problem because it's only in the brew path. But if the other two check valves are scaled, it may be as well. In that case the boiler refill problem would go away but the zero pressure during brew problem would not.

Similarly, given that the problem affects both the steam and brew boiler paths, it's very unlikely the autofill solenoid or 3-way solenoid are the problem unless perhaps both are clogged with scale.
Jake_G wrote:You should(n't) need to drain the boiler. But the machine needs to be cold and the steam boiler depressurized.

Cheers!

- Jake

Thanks to both of you! The problem seems to have been resolved when I replaced the check valve that threads into the tea water mixing valve.