Repairing the Over Pressure Valve on a Breville 860xl

20 Apr 2019 . Category . Comments #hardware #diy

The Breville Barista Express 860xl is a nice little semi-automatic espresso machine that I bought about 5 years ago for $450 (probably because the 870 was about to come out). While that might seem expensive, it’s maybe a third of what normal espresso machine cost with a grinder. I can make a mean latte with it that’s better than anything other than a top-notch coffee shop.

When it started leaking water, I looked into repair options (basically sending it back to the manufacturer to get a refurbished unit for $350) and considered buying a new unit (after all, $100 a year is only 20 store-bought lattes, and it had cranked out 600-800 a year).

However, there’s definitely a little repair community around espresso machines generally and higher end Brevilles in particular. Some parts are also available though not all.

After opening the case, I could clearly see whitish deposits around the leak area where water had evaporated/boiled off. It seemed likely to me that the rubber o-ring had failed (see picture at end of post). Unfortunately, that o-ring is not available for purchase, so I took a leap and bought some o-rings proposed as suitable replacements for another Breville model. They ended up being the wrong size, and I so I bought a part that included the o-ring. I measured the o-ring and made some measurements below that may help others buy the right size o-ring from Grainger.

The real trick in this is to take a lot of photos and take your time. The over pressure valve (OPV) screws off without removing other components if you first remove the stem and loosen the rubber mount plate. This means cutting a zip tie; I found HyperTough zip ties from Walmart to have suitable mechanical properties for this connection (6/6 Nylon and reasonably high temp; see picture). However, the stem tightness regulates max pressure, so you either want to image the threads before removing or count the number of turns as you take off. Another gotcha is that the plastic white washer at the base of the OPV is directional, so you may want to mark it to ensure it goes back in with the same direction. Finally, I had to reopen and retighten the OPV as it screwed into the base because I didn’t tighten enough the first time. Pictures of some key steps are below.