Bezzera BZ10: Leaking Between Portafilter and Group Head

Learn what to do when a Bezzera BZ10 espresso machine is leaking from between the group head and the portafilter.

If the machine is leaking from between the group head and the portafilter then the group head gasket is either pushed out of place and needs to be reinserted properly, or the gasket is worn out. Typically, group head gaskets will wear out in approximately 6 months to a year depending on how heavily the machine is used. Premature wear to this gasket can be caused by using excessive force when attaching the portafilter.

It is important to distinguish where the leaking is occurring. If the leaking is coming from between the portafilter and group head where you twist the handle on, then the gasket will need to be replaced.

1. To clean the group head, first unplug the machine and remove the water reservoir.
2. Place down a soft cloth or towel and tilt the machine on its back.
3. Use a flathead screwdriver to remove the screw on the bottom of the group head. Once the screw is removed, the shower screen and the diffuser plate can be removed.
4. Soak the parts that were just removed in a solution of hot water and backflushing powder.
5. Next the group gasket needs to be removed. The gasket on the BZ10 will have a few grooves around the perimeter. Use an awl or a small flathead screwdriver to pry the gasket out; the grooves on the gasket are an easy access point to help leverage the gasket out. Gaskets that are particularly old or worn out may get stuck into the group head. One trick is to partially screw some self-tapping screwing into the gasket; be careful not to go too far or the screws will puncture the other side of the gasket and possibly damage the group head. Then use a pair of needle-nose pliers to pull on the screws. The gasket will come out with the screws.
6. Once the gasket is removed use a group head brush or old toothbrush to scrub down the group head really well. Make sure to remove any built-up coffee residues or coffee grinds.
7. When the group head is clean the new gasket can be installed. The gasket will have a tapered edge and a flat edge. The flat edge needs to fit to the top of the group head, and the tapered edge needs to be exposed so that it can seal with the portafilter. Press firmly all along the edges of the gasket until it is fully in place and is not sticking up anywhere along the circumference.
8. Reinstall the diffuser, screen, and screw. Once everything is back together, firmly attach the portafilter a few times to help the gasket seat properly, but do not over tighten. If that does not resolve the leak then the gasket will need to be replaced.

The gasket can get stuck in the group head from wear or excessive heat exposure. To remove the gasket take some self-tapping screws and partially screw them into the group gasket. Make sure not to go all the way through the gasket because you can scratch/dent the group head if you go too far. Then use a pair of pliers to pull on the screws and the gasket will pull out with them.