My Machine is whistling.

[podo98]

After I pull a shot and sometimes when its sits idle, the machine will start a brief intermittent hign whistle. I called Chris' and they told me too loosen the expansion valve until it stops. I did it and it appears to have stopped, I do notice that after a shot there is a little drip out of the valve maybe for 30 secs or so, is that normal? Also what should the pressure (on the left) read when idle? Now it reads about 1.2-1.3 bar. Oh and my still are still undrinkable without milk.

[den99]

Man, you must of gone the wrong way on the GMT time when you signed up; I

[podo98]

Den99-

I have yet to get a drinkable shot. What bean are you using? Grinder etc?

[Niko]

I do notice that after a shot there is a little drip out of the valve maybe for 30 secs or so, is that normal?

Yes, this is "considered" normal.

I have yet to get a drinkable shot.

What grinder are you using?

[den99]

podo98, I have a Mazzer Super Jolly grinder. When I first got my machine I used Houston Coffee and Tea

[podo98]

I have a Mazzer Mini E

[podo98]

I am using some locally roasted beans, roasted yesterday. My grinder is set about 5 little notches finer than factory. Set at 94 deg. It tastes bitter all hell.

[Niko]

I have a Mazzer Mini E

I am using some locally roasted beans, roasted yesterday. My grinder is set about 5 little notches finer than factory. Set at 94 deg. It tastes bitter all hell.

It could be that you're over-extracting shots, therefore, bringing all the bitters into your shots. It could be that the blend is too young (fresh), some roasts are best after 1 week rest. There's so many variables that it can be any little thing that we're overlooking...
My finger points to a roast that is too fresh, mine have blonded too fast and channeled like hell on a few occasions when my roasts were too fresh.
Can you go into detail of the whole process of how you pull your shots? Like how many grams are you loading in the basket, how dark is the roast, your distribution technique, tamping style (what kind of tamper), etc.. and anything else you can think of.

[podo98]

I am dosing about 17-18g. The beans are medium dark not too oily. Roasted at about 444 deg. I am trying to use the Weiss method (yogurt cup stirring the grinds, leveling with finger in an X pattern, then tamping with an Espro). Pulling about 1.5 - 2 oz at 94 deg C. I use a naked pf. I am noticing a fair amount of perimeter channeling. Maybe 3-4 pin holes along the side. The extraction looks ok, Lots of crema. Tastes like crap. Very bitter like aspirin.

BP

[Niko]

Everything sounds good up to a certain point except where it tastes like aspirin, I know that flavor in coffee! I've experienced that with a couple of types of beans. It could be that channeling you're describing is just enough to extract the very worst out of that coffee, some roasts are not very forgiving and it seems that one might be one of them. There are some beans that no matter what I've tried, they tasted sour or bitter - I could never hit that happy middle ground.
How much space is between the coffee grounds and the shower screens? In other words, do you see the ridge in your basket after you tamp and how much of the ridge can you see?



And Denny,
I love your avatar!
It finally dawned on me that's a vehicle wrap (graphic) on the van, I thought what a jerk that van driver parked up against that nice sports-car!
I mean...it is a vehicle wrap, right?

[podo98]

I tamp to a hair below the retention ridge. Just so you get that slight impression of the dispersion screen bolt in the puck.

[Niko]

Yeah, that sounds pretty much perfect.

Did you try down-dosing it? Maybe something like 15 oz's to see what happens...grind a little tighter and maybe raise the temp a notch.
These are all little things I've tried for the "Aspirin Blend" I was going through a couple of months ago, I almost lost one of my tampers that evening...wanted to throw it through a window out of frustration (mostly because I was over-caffeinated).

I would try a couple more things before giving up, along with more rest for the coffee.
Try to get more espresso blends to try out, you may find that some other blend will give you the shot of your life.

[den99]

Yeah, that's a paint job on the van, it really looks like a car parked next to it until further investigation. Ha!