How to fix a La Marzocco GS3 pump on the cheap

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Recently the pump of my LM GS3 espresso machine broke. It was the second time the machine experienced this problem in a period of one year. The problem was quite substantial. The pump refused to run after pushing the brewing button. This brought me in a depressing situation. I wasn’t able to brew any espresso.

The cause of the problem

What was the cause of this problem? Inspection showed that the vane in the fluid-o-tech pump head didn’t turn smoothly. That made it impossible for the motor to drive the pump head.

pump head rotary pump
Failing pump head la Marzocco GS3

The been there done that fix

I knew how I could fix it. I just had to replace the fluid-o-tech pump head. That was something I had done before. It was effective, but only for a short time and it was very expensive. I didn’t want to spend a lot of money again on just a temporary solution. What could I do? Could this malfunctioning piece of machinery be fixed in another way?

On the cheap fix?

Most electric AC motors have an electrical part that’s called a run capacitor. This magical thing creates a rotating magnetic field after you press the brewing button of your espresso machine. The strength of the magnetic field is determined by the ability of the capacitor to store an electrical charge. In the 19th century a term was invented for this capability:  in honour of the English scientist Michael Faraday it was called Farad (F). On most capacitors you will find such a rating.

After reading on Wikipedia about start capacitors, several thoughts popped into my mind. What was the rating of my machine’s start capacitor? If it was too low, could I use a ‘stronger’ one? Could a simple ‘capacitor upgrade’ bring my machine back from the land of the dead?

Because I wasn’t completely sure about this fix, I called Peter from Kafko. He has a lot of experience  and he helped me out many times before. I asked him about this idea. He told me that this approach could work. First we needed to know the rating of the current capacitor. After studying the technical drawings I concluded that the thing should be in electronics box at the back of the machine. And yes, there it was, it had a rating of 7 micro Farad (7 uF). Peter told me that he would send me a 10 micro Farad capacitor for 12 euro. That’s a lot cheaper than a new pump head!

The capacitor swap

A few days later the higher rated capacitor arrived by mail. It was an easy job to swap the capacitors. You will need to be careful though. The capacitor will keep its electrical charge after removal, so make sure you don’t touch the electrical poles with your hands!


The back of the La Marzocco GS3
Inside the electronics box
7 uF start capacitor ready to be swapped
start capacitor rotary pump
This brought my machine back from the land of the dead

After installing I thought: Will it work? In a slightly nervous state I carefully pushed the brew button. Nano seconds passed. There was a spinning noise followed by water! The pump started running as if it had no broken past. The fix took place one week ago and since then there have been no issues. My daily intake of espresso based drinks has also been fixed and that’s good for my mental health and mood!

In case you are having troubles with your La Marzocco GS3 or another rotary pump you should definitely give this on the cheap fix a try!


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