Rancilio S27 steam from grouphead

Need help with equipment usage or want to share your latest discovery?

Postby devillighter » Oct 28, 2015, 10:14 am


I am in the process of fixing up a rancilio s27 that I purchased on craigslist a few years ago. I waited to fix it up until I moved into my new house and had room to work in my basement! The time finally arrived and I have enjoyed the rebuild process so far, but don't know how to fix some lingering problems. This is my first espresso machine rebuild, and first espresso machine period, so I don't know what I am doing for the most part. Browsing this site has been very helpful in figuring out the initial steps!

I disassembled and descaled the boiler, group head, and pipes in citric acid. I purchased new gaskets for the heat exchanger, boiler, and group head and rebuilt the steam wand and water dispenser. After reassembling everything, the boiler fills, it heats up, and the water dispenser and steam wand seem to work well. The machine is hooked up to a flojet pumping from a 5 gallon water jug.

My issue:

When trying to brew espresso, I get a ton of steam from the group head with very little water - a few drops at most. If the machine is cold and I hit the button to brew, i get no water from the group head at all, although I do hear the pump kick on. I am not sure if this is normal behavior. The pressure gauge to the boiler is not working, so I'm not sure what the pressure in the tank is. I hoped that the descale would fix that problem, but it did not. Last night, the gauge moved up, but then crashed back down to zero after some time, no idea why. Not sure if I caused this by overtightening the t-fitting on top of the boiler which cause me to have to bend the pipe to the pressure gauge to get things to fit. In addition, once the machine is hot, I continue to hear a ton of hissing from the anti-syphon valve, which from what I understand, should seal once the machine is up to temperature?

Not sure how I should attack this problem! My novice guess is possibly a pstat problem?


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Postby stuartmac » Oct 28, 2015, 12:55 pm

regardless of tank pressure you should get water from the group, i would address that first.

Check your hx loop water input, will be the small pipe attached to the bottom of the boiler, also check to see that you reassembled the 3way valve correctly and that the solenoid cable is attached and its operating.


is the auto fill functional, how much water is showing on the sight glass. ?
how long have you left it on to heat up?
did you try the steam wand after the machine had been powered up for a bit.

You can take the cover off the pstat to watch it , and see if its open or closed.

anti syphon valves sometimes dislike being de scaled are usually are better just to replace. ( i just finished a classe 8 and had the same issue)


Postby devillighter » Oct 28, 2015, 8:42 pm

Ok, I will attack the lack of water to the group first. Even if the machine is cool, just started, I should be able to get water out of the group?

I removed the three-way valve completely. This, in theory, should allow water to flow through without obstruction? When cool I get no water out of the group head when i hit brew. If it comes up to temperature I get a ton of steam. Going to work my way backwards to see what is happening.


Postby devillighter » Oct 28, 2015, 9:39 pm

Looks like the inlet to the flowmeter is pretty scaled up. I am going to descale this flow meter to clear this blockage.


Postby devillighter » Oct 30, 2015, 10:45 am

Ok, after descaling the flowmeter I now get water out of the group! Was definitely overthinking this problem. I was worried about pulling apart solenoids and other parts when doing the descale, so it is not surprising the flowmeter was descaled. Brewed my first espresso out of the machine as well!

I attempted to disassemble the pressure gauge to see if it was salvageable, but managed to mangle the internals in the process, so it looks like I will need to buy a new one.