Breville BES900 Group Head Leak

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by misicmil »

Hi guys,

I have one of the older versions of BES900. I got a leak from group head, actually once the coffee starts pouring from the spouts few seconds after espresso starts leaking on the left side of the portafilter holder.
So, I've changed:
1. portafilter seal, problem continued,
2. Group head collar, It's a bit of a work to get off the boiler and then replace the collar, but I've done that, I've found that the old one had crack, so I thought this would fix it. But the problem was still there with new collar
3. Group head basket, I am using vst20g ridgeless basket and to see if problem would stop I've changed to original Breville double basket, but problem is still there.

I apologize if this was answered somewhere but I've been trying to find all over the site and the best so far is that I need to change the group head collar what I did but problem is still there.

Any help would be welcomed.

Thank you


#2: Post by WWWired »

Hi misicmil :) The mighty BES900 is a true powerhouse developed by Breville as a huge leap forward in Dual Boiler systems for their Pro-sumers!

It might be worth unplugging the machine and then removing the top-lid/cover of the case and looking in around the Brew Boiler (the smaller of the two Boilers that is directly over the GroupHead) for any signs of water getting loose of the Hydraulic Pathways.

Were any signs of water intrusion seen on top of the group head when the Collar was replaced perhaps? Any signs of water intrusion or leaking from any of the fittings on the Brew Boiler, whether the smaller fittings for high pressure hoses, or the larger fittings that have Probes, may be revealed through a good inspection for any signs of water dripping out.

Below is an annotated picture (photo credit: Breville), showing the areas to perhaps look and where the water might be sneaking out. If one of the fittings inside the machine (or even the Grouphead assembly interface with the three-way solenoid near the back of the grouphead assembly and behind the Brew Boiler) is leaking water, this might first accumulate on top of the Grouphead (there's a little hot tub like area there) and then when more water drips/runs in, overflow and run over the between the edges of the grouphead assembly and the collar area. A good inspection of this area will help locate any possible leaking o-rings/fittings. Depending on how long this machine has been in operation, it may be time to replace the high-pressure hose #007 o-rings (smaller ones) and the slightly larger #010 o-rings (probes). If doing the Brew Boiler's o-rings, it might also be worth considering doing the high-pressure hoses and probe o-rings on the Steam Boiler (top) and inspecting the fittings on the side of the larger Steam Boiler for any signs of leaking, as well as the hose coming from the top of the OPV/Brew-Pump Assembly at back of the machine as there is a high pressure Teflon hose there was well with an o-ring seal.

Perhaps take a good look around the 3-way solenoid at the back of the Brew Boiler area too to see if any leaks are coming from where it is mounted onto the Grouphead assembly (which has kind of a Frying pan shape with the handle extending backwards). The photo below shows a possible leak path on the right side of the grouphead and as the leak is on the left, its the same channel for water but just the left side . . .