Looking for Marzocco GS3 Help with Grouphead Pressure Release - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
tomasso (original poster)
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Joined: 13 years ago

#11: Post by tomasso (original poster) »

Th Jake and Chris...very helpful.

Yes I already removed the nipple - or aerator - draining into the tray and except for a bit of coffee residue on the outside it was clean inside. There's no scale on it.

I don't have a gauge on top of my group head, if that's what referred to as "gauge turns." I bought my machine used, and as best I can recall, the group head was updated to the anodized blue version of the plunger.

Until recently, I could clean the group head and get a puff or spurt of water out of the nipple when shutting the paddle. Now it's inconsistent. I no longer get the spurt...sometimes I get nothing...and sometimes water slowly releases. I will try more cleaning first and see if that works.

If I move towards taking apart the group head, do I have to buy the tool or can I improvise somehow? If I take it apart, do I have to install the whole kit, or can I just replace the bad o-ring? I've seen kits for sale but not single o-rings. If I can replace just one, where would I buy it?

Thx again for your help! Tom

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Jake_G
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Joined: 6 years ago

#12: Post by Jake_G »

Ok.

You have an early MP with the blue helix shaft.

Here's the parts breakdown for that group:



The most likely culprit is item #3, which is a 012 size O-ring made of EPDM with a 70 hardness, but I'd recommend getting the kit, since the paper gasket is likely toast and you don't want any leaks after you're done. That said, the kit is absurdly expensive. They apparently switched to kalrez O-rings in 2016, and they are actually quite expensive to source ($45 each for the -012 size!). Not sure why the parts list shows the old part number.

The tool is UT004, and is basically an internal bearing extractor. After you remove the helix shaft, you drop the tool into the O-ring stack and tighten the nut on it to expand it and then lift the stack out with it. You could probably use a series of picks to get them out, but having the tool makes it much easier.

Here's a video on servicing the group:
Another consideration is to get the conical valve retrofit kit. It requires much less maintenance than the old style.

Cheers!

- Jake
LMWDP #704

tomasso (original poster)
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Joined: 13 years ago

#13: Post by tomasso (original poster) »

Thx, Jake. I remember looking at all of what you posted a couple of years ago. I assumed that I would eventually need to perform this task. Thx for posting it. I reviewed the video again earlier today.

I'm not really worried about the time it takes to replace gaskets. Everything looks simple. I've replace sealed bearings before on bikes and motors.

I found the removal tool for around $140, which seems overpriced, but it's Marzocco, right. As I understand it, the force to pull up the o rings is based on the o rings themselves - so there's no metal to metal contact - is that correct? I'm just trying to gauge how much force is needed to pull them up. Would it, for example, be reasonable to find a long screw with a head that is just big enough to go down the hole, then move it from side to side pulling to work the assembly up and out?

I also looked on eBay and found "9Pcs Blind Hole Bearing Slide Hammer Gear Puller Remover Set" that looks a lot like the Marzocco tool. Is there any reason to think that it would not work as well? I appreciate that damaging something could be costly. I just wonder if there's another way to do it.

Any additional thoughts you may have are appreciated!

Moxiechef
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#14: Post by Moxiechef »

I've got that tool. I also changed mine out to the new conical valve. If someone can confirm I don't need the tool to pull the confocal valve, I'll sell it to you.

I just can't remember if I need it to service the new valve.

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Jake_G
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#15: Post by Jake_G »

Moxiechef wrote:I just can't remember if I need it to service the new valve.
No longer needed on the conical valve.
tomasso wrote:I also looked on eBay and found "9Pcs Blind Hole Bearing Slide Hammer Gear Puller Remover Set" that looks a lot like the Marzocco tool. Is there any reason to think that it would not work as well? I appreciate that damaging something could be costly. I just wonder if there's another way to do it.
I'm sure that kit would work just fine, so long as it can handle something with an ID of roughly 9-10mm. There is a $30 kit at harbor frieght that says it can do 3/8", which might be small enough...

And yes. The only thing holding the stack in place are the 3 o-rings.

Cheers!

- Jake
LMWDP #704

tomasso (original poster)
Posts: 20
Joined: 13 years ago

#16: Post by tomasso (original poster) »

UPDATE. For the last 2 days, I've been leaving the machine on and periodically running it with a blind filter and cleaning powder. Yesterday I was able to get some normal discharge into the drain tray from the aerator. Today I got LARGE BURST releases of sudsy cleaning water from the aerator - almost like seeing a blockage overcome. I pressure it up for 10sec, then run quick 1 sec bursts to add pressure.

My sense is that an o-ring hasn't failed - as if it did, why would it begin working again? My sense is that coffee residue is clogging the pressure release path somewhere. I'll continue to clean and see if it goes back to normal.

Thanks for your help!

Splunge
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#17: Post by Splunge »

Good news!
Though weird that there'd be a blockage so far upstream. Jake would know better than me, but as a clue to the state of your group valve it might be worth checking inside the aerator (and maybe even behind the distribution screw/shower screen) for any chunks of o ring.
Chris

tomasso (original poster)
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Joined: 13 years ago

#18: Post by tomasso (original poster) »

Thx Chris! I'll keep that in mind. I've opened both the aerator and the group screen for cleaning - no rubber pieces inside....so far.

tomasso (original poster)
Posts: 20
Joined: 13 years ago

#19: Post by tomasso (original poster) »

About the same time that I was noticing slow pressure release, I had changed my pump pressure from 9bar to about 8bar to see if my pours were better. A couple of weeks later, wondering if this pressure release problem was exacerbated by the lower pump pressure, I adjusted it up to about 11bar. Lo and behold, the pressure release from the aerator into the drip tray was strong. I ran through some cleaner and flushed many times. The strongest pressure releases occurred when I quickly pushed the group paddle off after maybe 1sec of running the pump. Doing this one after another flushed a lot of cleaner through the aerator. After cleaning I reset the pump to 9bar.
From this I don't believe I have an o-ring issue. I think somewhere coffee residue built up in the pressure release flow channel. I don't know if my cleaning today was enough to cure the issue. Some coffee residue buildup is difficult to flush away.
Tanks to all those who contributed to my original post! The more information I have the better.

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