Recently, my beloved espresso (The Kim Express) machine was squeaking. The root cause was a lack of maintenance over 4 years since I bought it at an estate sale. Back then, I used a vinegar solution and ran it through a few times. I didn’t take the machine apart to do a deeper clean, and it seemed to run well. Some times things need to be taken apart to be able to get them to run to their full potential.
I brought it home, and I ran a vinegar solution again through it. I then thought I should take out the plunger because there could have been scale buildup in a place I couldn’t clean easily I looked online how to take out the spring and plunger to clean the inside. Now, this took a lot of time and elbow grease. It took half an hour to get it out with the help of two tools. The O-rings had swollen, so they did not move easily.
Finally, it popped out, and it was far worse than I imagined. There was 1 or 2 mm of resin buildup on the plunger head. The shower screen between the plunger and the coffee was mostly clogged. This probably caused water to flow into the coffee puck unevenly. I’m sure my coffee brew technique adjusted for the machine’s deficiencies or shall I say lack of maintenance.
I first cleaned the plunged by scrapping most of the resin off and then with a wet paper towel. I then worked on cleaning the shower screen. I scrapped it, wiped it, and finally poked through holes using a sewing pin.
This whole process took 3 hours. To get the spring back inside the machine, I had to use all my weight. Even then, the last O-ring had swollen too much. I saw a tip on line to use a heat gun, so I tried a hair drier. With some thoughtful convincing, it finally fit back into place.
Finally, I was able to go to bed. The next day, I took it into work, and it made a different cup of espresso than before. Even the colors coming out from the bottomless portafilter looked different.
But alas, that was not the end of this story. Water started coming out of the top, so I ordered O-rings because they were spent. At first, I did not measure, I just picked a size that looked close enough. I was wrong. So then I measured, and I waited three weeks to get some metric O-rings. They came, but they were too small. O-Rings have a wide variance, so even though I was looking for 3.1mm thickness, most were between 2.7 and 2.9.
So again, I tried a different vendor, and finally, I got the size I wanted due to the distribution. However, they didn’t work. I had measured wrong. I didn’t understand at first, but when I looked at them, the caliper has to barely touch the O-ring when measuring thickeness. I needed more like a 3.5mm thickness. I measured the metal part just in case, and it looked like a maximum of 3.8mm would go.
The day had finally come, the true test, and most likely the last because my wife was annoyed that I had spent $36 dollars on O-rings. I had waited 2 months, so I was very excited. They were a little larger than the originals, but they worked! Moral of the story: do maintenance more often so larger overhauls are less necessary.
As a postscript, the Kim started having some major squeaking and friction while pulling shots. I thought it was the main piston and tried more lubricant. Finally, I switched to a heavy, food safe lubricant, but I soon found out I needed to put some lube at the top. Probably because when the o-rings failed and shot water out the top of the spring where the lever is connected at the joint, the lubricant there was rinsed out.
Further readings of mine: