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How to fix a coffee Maker that is not brewing entire pot of water

Key Points

  • Most home coffee makers use a simple heating design to brew coffee
  • If you are having a problem brewing coffee, it is most likely due to a clogged check valve or flow valve

Table of Contents


I purchased and used my Mr. Coffee maker about 2 years. It was a fairly inexpensive model (ISX43-1) and is no longer being made.

I drink a lot of coffee but I neglected to clean it as recommended by Mr. Coffee. To make the matters worse, my city water is very hard (i.e. lots of minerals)

Here are some common problems I started to experience:

  • You put ten cups of water to brew but only get six cups of brewed coffee
  • Excessive gurgling noise
  • Excessive steam, fogging up the LED display

What is actually happening is that a small anti-siphon flow flow valve inside a supply water hose collects coffee grinds over a period of time and prevents heated water from entering the coffee grind basket.

When this blockage occurs, a cascading setpf events occurs:

  • Converted steam forces itself into LED control unit, possibly causing damage
  • Coffee maker itself over-heats, possibly increasing the risk of fire
  • More electricity is wasted brew a smaller pot of coffee

If you own a Mr. Coffee coffee maker or something similar for home-use, I will show you exactly how to troubleshoot and solve this problem.

Inaccurate Repair Information

Lots of sites have incorrect or mis-information on solving this problem, including naming parts that do not exist in most home coffee machines and “recommending” that you purchase “de-scaling” products.

Unless you own a commercial-quality professional coffee maker, please know that most home coffee makers have few parts that can break.

Required Tools

Below is a list of tools you will need:

Repair Steps

Cleaning the flow valve is covered in Steps #1-12 but highly recommend you complete all steps to clean and check all parts before putting it back together.

  • STEP # 1 – Remove the coffee grind basket, grill and carafe
  • STEP # 2 – Tilt the coffee machine to the side over a sink to drain any leftover water
  • STEP # 3 – Place the coffee machine upside-down. There are six screws in total: 4 Phillips screws and 2 Torx Security screws (size TT30). Torx security screws are under the hot plate area
  • STEP # 4 – Use a long-shaft Phillips screwdriver + Tamperproof Torx security screwdriver to remove all screws to remove the base cover plate
  • STEP # 5 – The exposed underside has several parts
    • A – cold water supply hose
    • B – heater
    • C – hot plate
    • D – hot water supply hose
    • E – electronic temperature processing unit
    • Blue arrow – cold water flow (from the reservoir)
    • Red arrow – heated water flow (to coffee grind basket)
  • STEP # 6 – We need to access the other end of hose D. Squeeze hose clip wings and slide it down the hose then carefully pull off both hoses from the heating element pipes
  • STEP # 7 – Remove four Phillips screws holding down the bottom assembly. In addition, it would be best to remove two smaller Phillips screws holding down the electronic control unit (blue circles) which will make it easy for you to detach the control wires (multi-colored) from the LED panel
  • STEP # 8 – Gently lift the bottom assembly from the shell while carefully re-routing hoses, power cord and wires
  • STEP # 9 – Clean the reservoir; please note that the hot water supply pipe (black plastic pipe, about 6 inches long) is removable
  • STEP # 10 – Squeeze wing-tips to pry off the hose clip from hose D and gently tug to detach the hose from the bottom assembly
  • STEP # 11 – Gently squeeze the hose near the end to push out the flow valve; take a note of the flow valve (water is designed to flow in one direction)
  • STEP # 12 – Use a toothpick to gently remove solidified coffee grinds from the ball / valve
  • STEP # 13 – Now we want to remove the “shower head” and soak it in 50/50 vinegar/water solution to dissolve any build up. You can remove it by pushing the showerhead well into the coffee grind basket then pulling it to the right
  • STEP # 14 – While it is soaking, gently remove the LED control unit and take it apart to check for rust.


Although I had to spend $12 to buy a Torx-security tool, I think it was worth to to fix my coffee maker.

I guess at minimum, I can find in comfort in that I avoided one more piece of trash headed for a dump!

Good luck with your repair!