New LM GS3 MP (less than a week).

At first, steam was too powerful if anything. I even reduced boiler from 262.4 F to 261 to get the bars down to about 1.5 vs 1.65.

But suddenly (past 24 hrs), steam power just quickly "evaporates". Steaming milk is basically impossible. This is very new behavior.

At first, when I "bleed out the water", steam seems fine (powerful). But when I actually steam now, power is clearly diminishing, and quickly. I cannot steam milk this way, only slightly warm it. Set boiler back to 262.4 F. No joy. Gauge shows a reduced pressure (after "steaming") but only down to about 1.3 bars, not nearly enough to indicate the near complete loss of steam power I'm eventually getting.

Ideas greatly appreciated.

Yuki

Two possibilities come to mind:

1. The steam boiler level probe is out of position. It should point straight down, or nearly so. If it's horizontal or higher, the amount of space for steam in the boiler will be reduced and you'll run out quickly. You don't have to take the probe out to determine it's position. The spade connector points in the same direction as the probe. If it points down, or nearly so, it's OK. If it's 90 degrees or higher, it's out of position. Loosen the lock nut to move it, but be careful not to loosen the main nut (hold it in place with another wrench.)

2. The probe sensitivity setting is too low and your water is low in mineral content. This could cause the boiler to overfill. Set the probe sensitivity to Mid or High.

Just reread your post. If the pressure after steaming only drops to 1.3 BAR, it seems unlikely you're running out of steam. Sounds more like the steam valve is closing partway after you open it. That can happen if the large silver nut at the front end isn't tightened quite enough. Usually what happens is the valve pops closed all the way, but it might close partway depending on how tight the nut is.

Thanks much. I've never cracked the case on one of these, but I guess I'm going to have to eventually. (Not terribly shy about it, just no experience.)

Yes, the 'hiss' of steam starts out strong, but very quickly declines to almost nothing, and it seems the manometer drops to around 1.3 BAR, and then goes back up rather quickly when I give up and close the lever.

Does this mean steam is likely being vented inside the case? That would not sound very good, but I don't see anything coming out of the vents.

If anyone has an old photo lying around, I'd be gratified.

Thanks again.

What might complicate this a bit for me is that side-arm lever. How straightforward a disassembly/reassembly might this be? It seems very clear to me that has to come off before I can remove the side panel.

Hi Yuki,
Have you contacted Dan about the problem? He may know whats going on since he built the steam valve...

I forgot you have a custom steam valve. Definitely a suspect. Make sure it's in the fully open position and watch to see if there's any movement towards the closed position when you're steaming. It may not take much movement to significantly reduce steam power. Also, try holding it fully open with your hand to see if the steam power stays at a high level. If so, the arm might need some adjustment to stay fully open. Ask Dan.

A leak from the steam valve or boiler is a possibility as well. I'd expect you'd see some vapor escaping from the top, but It's possible the vapor is condensing inside the machine before escaping, which is why you don't see it. That's not a good thing because the water can find its way into the brain box and disrupt or damage the logic board.

For this reason, and to check the steam valve/arm assembly, you must open the machine. You can get a pretty good view by removing the right panel and the top. For the top, remove the cup tray (might be a bit hard to pull out -- I use a hex key to pull up under one edge to loosen it.) Then remove the screws that hold the top on (usually two screws), and remove the top. It should come right off (if both sides are on it'll be wedged in too tight, but with one side off it should come out OK.) Now you should be able to look straight down at the steam valve, arm mechanism and right side of the boiler.

I suspect that if you remove the arm, which may just press on or is held by a small screw or two, you can remove the left side panel. Ask Dan for help.

Thanks Dick. Yes, I've emailed Dan, and very hopeful he'll have the answer.

Btw, I do see some steam escaping at a certain point during warm-up, but then something seems to occur and it just stops. I was assuming there was some kind of pressure valve or something that reached a certain level, and that it was all normal. Is it?

I'll work on pulling the right side & top today, and hopefully I'll hear from Dan, too.

Thanks again.

Dick, your comments about steam inside (esp possible brain box damage) have me reluctant to turn on the steam boiler (even the machine itself, actually), but it seems necessary to do that to diagnose the problem.

Am I worrying too much?

You can just open the right side panel and have a look at the boiler, that should be pretty simple and should not affect the side steam lever. Have a look at my post on installing a side mounted steam arm, to see photos of what the inside looks like. I feel like the steam dying out maybe due to the steam valve closing in, I'm just speculating.

Here's the link to my post
DIY La Marzocco GS3 Side Mounted Steam Lever