Question about Bialetti Moka Express 6-Cup Coffee Maker

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Howdy, I have a six-cup Mocha Express. Lately when I've been making my morning brew, it makes a high pitched whistle (like a tea kettle boiling) towards the end of the coffee brewing. I have a feeling there's a coffee ground stuck somewhere. Any thoughts on how to end that sound?

Posted by jonathangrac on


1 Answer

Mark Cheong

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Stove top coffee espresso brewers; have three compartments, the lower is a sealed water tank that once heated will push boiling hot water and steam through the coffee grounds and over flow into the 3d chamber at the top of the pot. It is finished once all the water has boiled out of the lower chamber.
* Naturally when you boil water in a sealed chamber it's going to pressurize to the point where something will give. In this case it's the coffee grounds. But what if the grounds plugs up the filter and pressurizes it beyond what the chamber can safely contain? This is where the safety valve will sense the over pressure and release the excess steam. You will see and hear a loud hiss and steam exiting from the side where this valve is.
* The safety valve is not adjustable. Pre-mature blow out (of steam) can be caused by too fine a grind on the coffee, Turkish grind is finer than espresso. This tiny grind will clog all the filter holes. Use the standard espresso grind which is 1 size up from Turkish grind.
* The safety valve may blow if too high a heat is applied to the pot. Turn down the stove to a lower setting to give the hot water and steam time to flow through the coffee. If you observe the coffee as it oozes out of the center post. It should be a steady flow (like lava) with a gush of steam near the end of the brew when the top pot is full.
* The safety valve can get clogged which needs to be cleaned and checked PRIOR to filling and using.
* when in doubt. change out the safety valve. You could check with your vendor or MFR for replacements. Also check for the part.
Aloha, ukeboy57

PS; There a numerous videos on how to clean and maintain these pots. (I do NOT recommend Descaling). Here is one that looks safe:

Posted on Feb 12, 2018


5 Related Answers


SOURCE: Cleaning problems

Hi - I just clean mine with hot water (no soap), and dry it with a towel then leave it on the window sill... My problem is that the coffee can taste a bit metallic at times; and i want to know if I should be cleaning it after every time I use it... Suggestions?

Posted on Jun 23, 2008



  • 1 Answer

SOURCE: 6 cup only making one cup

I've finally discovered the solution to this problem. When the water is boiling and you can hear it trying to come up thru the coffee maker, pick up the Bialetti Coffee maker about 3 inches and just hit it back down onto the burner of the stove. You don't have to go crazy here.

Before you start making coffee just make sure the strainer is clean where the gasket attaches as you might want to blow through it and all parts are dry before you put coffee into that little metal cup.

Posted on Sep 01, 2008


  • 4 Answers

SOURCE: 6 cup moka express only making 1 cup of coffee

The funnel cup where you put the coffee may be bent out of shape, even slightly will be enough to let the pressure escape without the steam properly going through the cofee.

Posted on Jul 16, 2009


  • 7 Answers

SOURCE: Espresso irregularly spurts out the center post

It IS the gasket!!!!! Store the pot with the two parts screwed TIGHTLY together for about a week. Tighten it up as the new gasket compresses. Problem solved in two weeks or less. Funnel had NOTHING to do with my problem. Also cook on medium to low heat. High flame seems to make the problem worse.

Posted on Jul 17, 2009


  • 7 Answers

SOURCE: barely any coffee rises to upper chamber after cooking

It's the gasket!!!!! Store the pot with the two parts screwed TIGHTLY together for about a week. Tighten it up as the new gasket compresses. Problem solved in two weeks or less. Also cook on medium to low heat. High flame seems to make the problem worse.

Posted on Sep 12, 2009

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I've been using the same kettle on my stove for about a year and I hadn't cleaned it even once until last week.
A while ago I started noticing these weird white chucks that would come out with the water but I just figured that it was because I get a lot of use of out my kettle.
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