Breville BES900 Dual Boiler - Owners thread

[noidle22]

No luck with the new pump, machine still doesn’t do any pre infusion and there’s no primary brew pressure either, even though I can hear the pump running.

There's a high chance that there's a failed teflon seal in one of the solenoid ports that is restricting flow. A brand new pump should have repaired the issue if it was indeed the pump at fault.

On a certain build date range of the machines, Breville started using teflon discs instead of the large silicone seal for the group solenoid. They did not install metal reinforcing tubes in the middle of these discs and over time, the hole in the disc would close up and severely restrict, or even stop, water flow.
In later revisions, the metal tubes were installed at the factory.

If you remove the solenoid, you should be able to see fairly easily if there is a problem with one of the discs. Make sure the machine has been off for a while and the group head is cool. If it's hot and you remove the solenoid, hot water can spray out.

[Janus]

Thanks Noidle, i had removed the solenoid to see if there were any visible blockages previously when the pre infusion had initially started playing up (there weren't). My solenoid has a silicon seal with small metal tubes, is there any way to clean/recondition this or does it require replacement?

[pcrussell50]

On a certain build date range of the machines, Breville started using teflon discs instead of the large silicone seal for the group solenoid. They did not install metal reinforcing tubes in the middle of these discs and over time, the hole in the disc would close up and severely restrict, or even stop, water flow.
In later revisions, the metal tubes were installed at the factory.

I can confirm this. ^^^ I got a new solenoid in 2015 that had the teflon discs AND the metal reinforcement ferrules. The metal reinforcement is a sensible thing, as PTFE is known to cold-flow.

Here is a picture of mine after about three years of service on this particular solenoid, right after I removed it. There is a little bit of clear residue. That was a little dab of silicone grease I put in place when I installed it, to keep the silicone discs from falling out when I was lowering it into position:


Here is a more detailed view of the discs and the metal tubes that support the holes, cleaned up a little before re-assembly:


At the time the picture was taken, my pump would make full brew pressure, but would not pre infuse. Changing to a new pump did not fix the lack of pre infusion.

-Peter

[noidle22]

Thanks Noidle, i had removed the solenoid to see if there were any visible blockages previously when the pre infusion had initially started playing up (there weren't). My solenoid has a silicon seal with small metal tubes, is there any way to clean/recondition this or does it require replacement?

The silicone seals don't fail in the same way that the teflon discs do. I've never had any problems with them.

It's possible there's a blockage somewhere else in the brew path or that the new pump is faulty. I personally have always had success with installing new pumps to fix preinfusion problems and am yet to see a faulty circuit board be the cause. I'm sure it's possible for the board to be at fault but from my experience, it would seem very unlikely.

The fact that your new pump doesn't even give full pressure is strange. What happens if you try the hot water tap? Does the pump run and water flow from the tap normally?

[pcrussell50]

Noids, I don't want to take anything away from your pre eminence as a knowledgeable repairer. And I feel like I've been crossing you with my contrary posts. That is not my intention. At all.

When I had my -900 that stopped pre infusing, (but still made normal brew pressure), I tried a brand new EX5 (with the brass neck and a new brass OPV in that old -900. It was the "newer" -900, with the -920 group that requires the notched portafilter. Anyway in the old machine, even with the new pump, it still would not pre infuse, but it would develop normal brew pressure. BrevilleUSA decided they couldn't or wouldn't fix it, so they sent me a new -920. The very first thing I did with that brand new -920, before even plugging it into the wall, was to take out the plastic EP5 and plastic OPV and put in the same brand new EX5 and Vibiemme brass OPV. And it works and pre infuses normally... With the same EX5 that didn't pre infuse in my old machine.

Since this experience is outside the bounds of your experience, I feel it may be one of the less common failure modes and worth discussing the cause. It also sounds a bit like the difficulty Janus is having.

-Peter

[noidle22]

Noids, I don't want to take anything away from your pre eminence as a knowledgeable repairer. And I feel like I've been crossing you with my contrary posts. That is not my intention. At all.

Not at all, it's just discussion on a topic. I can't profess to know everything about these machines and there will always be cases that I haven't experienced yet.

Since this experience is outside the bounds of your experience, I feel it may be one of the less common failure modes and worth discussing the cause. It also sounds a bit like the difficulty Janus is having.

I hope to get a machine eventually that doesn't pre-infuse even with a new pump. In this case I will replace the main circuit board or if i have time, just replace the components that make up the pre-infusion circuit. I would anticipate that these would fix the issue as there isn't really anything else it could be.

[Janus]

Breville BES900 Dual Boiler - Owners thread

So is the 3 way solenoid valve replacement essentially a brew group replacement? To me it looks like the part that can get blocked is a part of the brew head? Otherwise the part that screwed off the top of the part my finger is pointing to seems to have decent flow, I can blow water through it easily enough.



Also I’m slightly unsure how it works, there are 2 pumps. One I assume pushes water through the group, and the other is for filling the boilers? It looks like the pressure from the brew pump runs through the boiler for the steam first though?



It looks like both pumps run into the steam boiler, one at the side down the bottom and one into the top, with a line then feeding from the top of the steam boiler to the brew boiler?

Also my valve looks like this:



Edit - ok google says the solenoid valve is the bit that I detached from the part my finger was pointing to. If that’s the case there’s no visible gunk...

[Janus]

Breville BES900 Dual Boiler - Owners thread

I plugged it in and the pump is not getting water. I can see bubbles of air in the line and eventually it goes dry.



Below where the water feeds in there are also bubbles in the line.

[Janus]

Breville BES900 Dual Boiler - Owners thread

Ahhhh.. appears the valve from the water tank was stuck closed. Have jammed it open, and I’m getting hot water from the water pipe.

I’m getting pre infusion and full pressure. So it appears I may have had 2 issues, a stuck water valve from the tank, and a broken pump.

Further testing this evening will ensue.

[Janus]

Breville BES900 Dual Boiler - Owners thread

We have pre and brew pressure. Happy days. Just made a couple of FW and all seems to be working properly. Coffee tasted good.

** morning update, machine working as it should. The ramp from low pressure to high is a bit slower than before, which is probably a good thing. Coffee tasting good.

[BOR15]

Janus, water for the group head runs through the steam boiler to get pre heated. thats how these unites keep such a steady temp and recover so quickly

[inertia8]

Excellent to see this thread still going.

My 900 is making twanging/buzzing noises from the pump when it first gets energized, still seems ok but i suspect I'll be replacing it.. might as well go brass with brass opv at the same time, so thanks for the links.

I also have a dripping steam wand and occasionally hear a noise as if a water drop is dripping onto the boiler, haven't opened the machine up, however I think I need to investigate sooner rather than later based on your findings about steam leaks!

Just following up on this, the behaviour remains the same... twanging buzzing noise when first hitting the shot button, which softens and continues during the shot pour. Pre-infusion pressure seems vastly reduced.

My leaking steam wand is getting to point where I need to do something about it.

I presume my first port of call is to grab a bag of those #007 o-rings and maybe an Ulka EK5 pump. My plastic OPV was replaced some time back, but cannot recall if the pump was replaced or not.

There is still the sound of the leaking within the machine and I'll have to work out what's going on there.. it basically sounds like a drop of water if leaking onto the top of one of the boilers and hissing as it sizzles and evapourates! Can't be good!

[inertia8]

As if to spite me for making this post... Making a coffee this afternoon the machine continued to make that buzzing noise during a pour..

I read earlier in this thread that cleaning the machine made the buzzing stop for a fellow user.. well, it made mine much worse! During the cleaning cycle the group seal went, water spurts out all around between it and the portafiler. The portafilter does not move and try to come off, it used to do this but the whole group head was replaced during it's final "in warranty service" and hasn't been a problem since, it maybe moves 1-2degrees sometimes but generally not.

My machine was in for repairs about a year ago costing $350+, adding and now I'm considering my options.

1) diagnose and repair it myself
2) have the shop do it, potentially another big bill and almost half the cost of a BES920...
3) Buy a BES920 during the next sale

Can someone help with the diagnosis?

1) buzzing sound cause. Is it likely to be the pump, a solenoid or combination of both?
2) Leaking steam wand. Is it the ball valve or just an o-ring?
3) Leaking group seal. Seal itself or will I need that plastic piece to help the handle exert more pressure against the seal?

-EDIT:
1) buzzing is solenoid, potentially disassemble and clean.
2) Potentially just a disassemble and clean
3) Seems this the leaking seal is more likely the black plastic group collar insert being worn and not exerting the pressure on the seal



Thanks in advance!

[inertia8]

Ok, curiosity got the better of me and I took the lid off to see what was what.

Two leaks causing the hissing drop of water on frying pan noise... one from the connection of the pump to boiler, this one leaks after the pump is disengaged. the other leaks from the water level probe(?) it actually leaks between the shaft and the body of the probe itself.


Here are some general condition pics:

[pcrussell50]

-EDIT:
1) buzzing is solenoid, potentially disassemble and clean.
2) Potentially just a disassemble and clean
3) Seems this the leaking seal is more likely the black plastic group collar insert being worn and not exerting the pressure on the seal


Thanks in advance!

You've been doing your homework (reading), or your intuition is right on the money. Either way, what you have concluded in your edit is very good. I'll add if I may:

1) solenoid: disassembly and cleaning may stop the buzzing. When I disassembled and cleaned mine, I found very little to clean however, so I just assumed that cleaning was no help, and I replaced it with a new one. This solved the buzzing. For some reason, new solenoids seem a good deal cheaper in the USA. I have heard of good luck though with disassembly and cleaning up. So do it and tell us what you find out.

2) steam ball valve: unfortunately, when you start getting dripping out the steam wand, it's the seals inside of the valve, which I have heard almost no success stories of fixing. Replacement is the only thing I know to have worked here. It also look like you need to replace the #007 o-ring where the ball valve attaches to the bottom. This works the same way as replacing the #007 o-rings under the PTFE hard tubes on top of the steam boiler. New ball valves have been out hard to find lately at the parts houses.

3) plastic group collar: I have heard of no fix here, just replacement. These have been out of stock for a long time in the USA parts outlet. They only just got them back in stock.

4) your pic of a water drop coming out under the silicone boot on the steam boiler is the classic #007 o-ring leak we all get eventually. The silicone boot might be "glued" in place by some silicone sealer, so you might need to wrestle with that before you slide the boot up the tube and out of the way. Don't lose/drop the little spring clips that looks like hairpins.

-Peter