Hi all,
I am hoping somebody can help me resolve an issue I am currently having with my Bianca. When I backflush the machine, it frequently dribbles out a TINY bit of water. I often have to remove the blank portafilter to release the pressure, relock the portafilter and try backflushing again. Sometimes it will take several attempts before I see the level of backflushed water that I expect. I tried corresponding with Clive and they told me it was within the "normal range" of what they would expect to see. When I say "tiny," I mean tiny - 1-2 ml of water (I am trying to figure out how to upload a video). I have owned several other e-61 machines and never seen a backflush that releases so little water. I make sure that the flow control is completely open, so much so that I have taken the knob off to fully open it in an effort to isolate the problem. It makes no difference.

Has anybody seen this before? Is this truly within the normal expectation? Is this unique to the Bianca or other flow controlled machines? Thank you all for your wisdom!

My suggestion would be to completely disassemble the Group, inspect all of the parts, and replace everything that's worn and/or corroded.

It has been behaving like this since the machine was brand new (the machine was purchased brand new in late 2021 and has only seen rpavlis water).

I would focus not on the amount of water specifically but at the amount of pressure that you are building "UP" to do the backflush, and even more so if the gauge shows you,
possibly you are not waiting enough to create a full pressure to reach the set up before OPV opens,
if you reach 8-9-10 bar during brewing there is no reason why you should not reach the same with a blind filter on,
unless the OPV opens sooner but that means that it will open sooner as well during brewing

Before to any "invasive" operation, should be better if the OP will find the way to post a video, i frankly don't understood his statement: " When I backflush the machine, it frequently dribbles out a TINY bit of water. I often have to remove the blank portafilter to release the pressure, relock the portafilter and try backflushing again."

Thanks, Stefano. Yes, I am able to get full brew pressure both from the pump and also at the flow control.
What I mean is that if the backflush does not expel much water, I have to remove the portafilter and lock it back in place. After the removal and repo king the portafilter the backflush will expel a normal amount of water.

Here is a video:
http://www.vimeo.com/822025776

Thanks for posting a video Andrew. Some things I notice:
-The steam pressure is over 1.5bar, is that correct for a Lelit Bianca?
-The brew pressure is also high
-The lever squeaks during operation, indicating to me that the components inside are scraping metal to metal, without grease, and the group needs to be disassembled, cleaned and serviced
-The machine is very dirty outside, and I'm guessing (as I mentioned in my first post) that it's dirty inside as well

I don't think you'll resolve this by saying that the machine is not old and only uses X type of water.

It looks to me like there's no detergent in that backflush. I don't see anything wrong in the video, if you're backflushing with just water, there will be very little air and absolutely no detergent trapped in the brew chamber, so there will be almost nothing there to expand (liquid water can't be compressed), so almost nothing will be displaced out through the drain when the drain valve is re-opened. It looks okay to me.
The sounds, however, don't sound perfect. What makes that wailing noise after the lever is all the way down? It's not just brass on brass squeaking, the cam isn't moving at that point.

I agree with Todd that you probably want to take the valves out, clean them and lubricate the ends where they ride on the cam.

Do you completely push back the lever ? By your video seems the lever is in a different rest position at the beginning of the video. Anyway , as suggested by austinado16, a better check, especially of the lower part of the group head, is a good idea.

how old is the machine?
How often do you backflush with detergent?
Do you remove the lever and lubricate after backflushing with detergent?
Have you ever removed the lever and lubricated the camp pins etc.?
What do you lubricate them with?
How often do you backflush with detergent?

The squeak is after you lower the lever, so it's not the cam pins squeaking. More water should come out than that when you release pressure, or backflushing wouldn't work.

Remove the lever, take a detailed photo of the cam pins....I suspect the vent valve isn't opening properly sometimes.