Hi there,

This is my first post after years of lurking and from reading the great advice that's been given on these forums, I could do with some myself!
I recently upgraded my dual boiler E61 to a new LM GS/3 MP. This is obviously a very different machine to the E61's that I'm I'm used to and I noticed a few oddities that I'm hoping I can get some advice on.

Firstly, I noticed a very small leak/weep from the brew boiler to expansion valve connector. A drop of water was hanging on nut that connects the copper pipe to the brew boiler (I've tried to attach a photo of the area below) I wiped it away and left the side panel off to monitor it and very slowly, water begins to appear. I've checked that the nut isn't loose.
Would it be best to replace the complete part (copper tube, nuts etc) or is there a better way?

My second question is regarding the brew pressure gauge when activating the pump with no portafilter engaged.
When I do this, the gauge shows 8.5 bar and then a few seconds later, there's a slight change of sound which I think is coming from inside of the group head, accompanied by a 0.5 bar raise in pressure on the brew boiler manometer. It doesn't seem to happen everytime and only happens when there's no portafilter in the group.
Is this normal - has anyone else noticed this?

My last question is about the ease of movement of the hot water wand.
It seems to have quite a lot more resistance to movement than the steam wand. When I move the steam wand, it moves easily and stays in the new position when I let go.
The hot water wand on the other hand required more force to move and when I let go it sort of springs back a few mm's.
I have to say that this doesn't really bother me as I rarely use the hot water wand but it'd be nice to get it moving in a similar fashion to the steam arm.

Apologies for the long post but would appreciate any advice.

All the best

Call LM. It isn't okay.

If this were an older (past warrantee) I'd suspect that the fiitting wasn't sitting flush. So I'd open it with a wrench and hand tighten while wiggling the pipe so that the fitting sits flush.

But if it is new I wouldn't do so without the direction of LM support. So in case the fitting is somehow damaged - however unlikely that is - you wouldn't void the warrantee by doing it on your own.

Thanks for the quick reply. I've called LM and I'm waiting for a call back. What do you think about the brew pressure gauge and hot water wand?
Cheers

I've reassembled my AV version many times. So I know the fittings very well.

Mine doesn't have a hot water wand so no experience with it. I can't tell if it is expected or not but will say that steam and water behave differently (steam being pneumatic so springy and compressible - while water is hydraulic and incompressible). So I would expect them to behave differently.

As for the pressure lag sounds like PI (gicleur and headspace) taking place. Again my machine is an AV so I don't know if MP behave the same or not.

Surely others with an MP can chime in.

I owned a GS/3 a few years ago and I suspect that the problem with your hot water wand moving a few millimetres when you let go of it is due to the position of the spring that provides the tension to hold it in place.
If you move the wand sideways as far as it will go towards the right rear of the machine this may rotate the spring in its mount to a different position, and so solve your problem.

Thanks for the replies.

I did wonder if the brew pressure change involved air somewhere. The group is properly bled and the machine runs off the internal reservoir if that makes any difference?
I've made a quick video of the change and put it below.
In case you're wondering, I've reduced the brew pressure to 6 bar to experiment with the taste - I've heard good things!
The pump output pressure setting doesn't seem to impact the pressure change/noise.

Thanks for the tip about the hot water wand. I've tried rotating it a few times but still the same. I did notice that the steam wand ball joint sits slightly lower into the machine than the hot water wand so not sure if that's correct or whether that may have something to do with it?
Thanks again for taking the time to post
http://www.youtube.com/watch?v=jX0zFl5l4S4

I don't think that the steam wand ball joint sitting slightly lower in the machine will be making any difference, sorry.
Also, i looked at the video you linked to and i'm afraid that i cannot really see a problem.

I would wait until you receive a response from LM.

Thanks,

I'm sure there's nothing wrong but I'm just curious as to what causes the change in noise and slight pressure increase when the pump runs freely and why it happens sporadically.

Are there any other GS/3 MP owners out there who could say if their machine behaves in this way?

I have a GS/3 AV, but my comments apply to the MP as well, except possibly regarding the pressure lag/jump:

Drip at Brew Boiler Tee

Assaf is correct that with the machine being brand new you should get advice from LM before attempting to correct the drip at the coffee boiler tee.

I recommend that you turn off the machine until you hear from LM. Although the drip is small and slow, any water accumulation on the chassis floor could find its way into the brain box, damaging the logic board. Since you're not plumbed in, the boiler pressure should go to zero when you turn off the machine, and the drip should stop.

FYI, there's a small "nipple" at the end of the copper tube that the nut presses against a hole inside the fitting. Although you checked that the nut is tight, it's possible yours needs a tad more torque to get a good seal. But don't do that unless LM directs you to do so. The nut has to be torqued somewhat more than finger-tight, but shouldn't require very high torque -- over-tightening could damage the nipple, fitting or nut. If you're lucky, you'll just have to tighten the nut slightly to get a good seal.

Other possibilities are that tiny debris got between the nipple and fitting before it was tightened, preventing a good seal, and the small, slow drip wasn't noticed when the machine was tested by LM. In that case, you would drain the boiler, disconnect the tube and clean both the nipple and fitting. Or, it's possible that the nipple or fitting isn't smooth due to a manufacturing defect or damage somewhere along the line. Or, the solder joint where the nipple meets the tube is defective or has been compromised by over-tightening. In these cases, the part or parts will have to be replaced. Although I would probably do the repair myself, I think LM should arrange to send a tech to your location to do the work, which should be completely covered by the warranty. I would think they have plenty of qualified techs in London.

Tea Wand

Mine was quite tight when I got the machine, and remains so today. I have the"spring-back" effect, too. I don't think this is abnormal. You don't want that wand flopping around. However, yours might loosen up a little as you use it more. Note that somewhere along the line I rebuilt the tea wand joint because LM replaced a plastic part prone to binding with a metal part. The movement was a little smoother, but still quite tight. I wouldn't worry about it.

Pressure Lag/Jump

I thought my GS/3 was the only one in the world that did this! Well, it used to. Much more on that below.

But first, I don't see a pressure jump on the brew boiler gauge in your video. It doesn't look like anything is wrong, though I can hear the slight change in pitch, which also occured with my lag/jump problem. Perhaps you could post another video that shows the lag/jump more definitively.

I've laid out my long pressure lag/jump story below, but it may or may not have anything to do with your situation. Before you read on, however, bear in mind that it's possible your lag/jump has something to do with the leak at the boiler tee. I would get that taken care of first, then determine if you still have the lag/jump.

I must hasten to point out that I modified my GS/3 AV by replacing the rotary vane pump with an outboard variable speed gear pump for pressure profiling. However, I did observe the lag/jump phenomenon occasionally when I had the rotary pump, though not as often. That pump was outboarded, too, which could have something to do with it.

Here are some videos showing the phenomenon:

http://www.youtube.com/watch?v=5CJ0xv9Q7qc
http://www.youtube.com/watch?v=_jC4QUezE-A
http://www.youtube.com/watch?v=p3XUOKFWDT8

The first video shows normal free flow at 9 BAR. Then I do a backflush (gear pump speed lowered to keep pressure below 10.5 BAR). After that, the free flow pressure drops to 8 BAR. Sometimes if I run free flow several times it'll jump back up to 9 BAR. In this case it didn't jump, so I increased the gear pump speed to the 12 BAR setting. You can see that it sticks at about 11 BAR, then jumps to 12 BAR. Note the difference in the sound of the flowing water before and after the jump. After that, free flow at normal speed is back to 9 BAR.

Often I saw the lag after the machine had idled for a few minutes, and it happened after almost every backflush and after almost every shot.

Oddly, if I drained the brew boiler, refilled, it, and bled the group, the lag/jump would go away for a while. But it always came back. I could temporarily force the jump by letting the group run or by running the pump at high speed (12 BAR) but it always came back -- especially after backflushing or pulling a shot.

Note that the lag/jump was more frequent and the lag was more persistent when I lowered the line input pressure to the pump (my machine is plumbed in.) I sometimes do this to achieve very long, slow pre-infusion for Slayer-like shots of light roasts (you can do much the same with the paddle of your MP.) Anyway, I suspect that your problem could be caused or exacerbated by the fact that you're using the reservoir, which has zero input pressure. That said, to my knowledge other reservoir users haven't reported a problem like this.

Side note: seems to me the low pump pressure (6 BAR) that you've set could make the problem worse. And my experience has been that lowering peak brew pressure doesn't have any positive effects on taste in the cup, and when you get below 7 BAR the effects are mostly negative.

At one time Assaf had a theory that the rubber tubes inside the long braided hoses I was using for outboarding would "give", slowly expanding as pressure built, and when they reached max expansion the jump would occur. But I was able to disprove that theory by replacing the hoses with short, solid tubes.

For a while, my theory was that dissolved CO2 (carbonic acid) in my relatively hard well water would come out of solution when heated, forming gas bubbles that took time to compress. The lag/jump time would vary with the amount of gas released and the input line pressure being used. But it seemed like the pressure change would be more gradual if that was the case, not a sudden jump.

I recently discussed the phenomenon with several techs at LM USA. Their leading theory was that it could be caused by "standing wave" resonances in my machine. They've seen this phenomenon in other machines, but it's rare. One suggestion was to slightly increase the diameter of the flow restriction hole in the flow meter. This might change the fluid dynamics just enough to eliminate the resonances. We also speculated that the problem might be caused by a worn or misaligned flow meter impeller. I ordered a replacement flow meter so I could go back to stock if enlarging the restrictor didn't work. This also provided a new impeller to test. (Note -- your MP doesn't have a flow meter.)

However, before doing this, I installed a new TL-30 tube that LM has just come out with. It moves the gicleur (another, much smaller flow restrictor) from inside the boiler to the interface with the 3-way valve outside the boiler (note -- the MP has a different gicleur setup.) This makes it much, much easier to replace or clean the gicleur. The replacement required opening the group, so I had to drain the boiler. When I refilled, I bled the heck out of it. I normally bleed the group several times after a refill, but have always noticed tiny bubbles continue to come out no matter how much I bleed it. I believe these are the result of "flash boiling" of the hot water when it hits the air, but I'm not certain about that. So this time I bled and bled, maybe 20 times. This didn't eliminate the bubbles completely, but did seem to reduce the number.

Lo and behold, the lag/jump has been gone for three weeks now. I don't see it with low line pressure, either. I'm not ready to declare victory quite yet (it's sometimes taken a week or so to return after a drain/refill), but I'm mighty encouraged.

One might speculate that debris stuck inside the original gicleur caused the lag/jump, but I saw nothing in it, and I had replaced the gicleur a couple of years ago anyway, when I replaced the copper TL-30 tube with the improved stainless version.

My conclusion is that it was either standing wave resonances, as LM speculated, which changed when I moved the gicleur, or was due to the very thorough bleeding I did. My bet is on the former. I will try to confirm this next time I drain/refill the boiler.

Like I said, the causes of my lag/jump may be entirely different than yours. If so, I hope you enjoyed my story .