Dual Boiler Ulka E61 (Quick Mill QM67) draining back to reservoir

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
Zachary37

#1: Post by Zachary37 »

Hi all,

Been lurking around this forum for several years and have never been hit with a problem that I couldn't fix through search. Thanks for your contributions.

I have a QM67 that is about 6 years old. It has been steady eddy with just a little maintenance until the past couple of weeks, when I pulled the lever and all I got was the pump running, no water through the group. I noticed the first time that the grouphead was cool (syphon issue). The boiler temp dropped, got back to temperature, and went on for a few more days without issue. It then started happening consistently every morning.

I first changed the Ulka pump. (I was also running into to duty cycle problems sometimes, so this made sense to me.) I put in an EFX5. This seemed to help at first but the problem came back. I changed out the brew valve next. Still having problems. I noticed as it was heating up this morning (I'm not usually in the room when it is heating) that it was bubbling in the reservoir. I had a look and the water level was at the very top, and I know it wasn't full yesterday.

When I flipped it on and off several times (not the power but the lever), the water level in the reservoir dropped back down and so did the boiler temp. Once it climbed back to temp I could pull shots normally again.

I'm sure someone knows exactly what's going on. A little advice on the next step would be appreciated.

Thanks,
Zak

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BaristaBoy E61

#2: Post by BaristaBoy E61 »

Welcome to HB Zachary!

I would suggest checking the vacuum breaker operation and see if the machine has a check valve to prevent back flow into the reservoir tank, if it does you can also see if you can verify it's proper operation too.

What happens if you open the Steam Wand spigot during boiler heat up?
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

JRising

#3: Post by JRising »

Yes, you've discovered the problem. Trace it. Follow the flow, the entire route through which the Brewer water is escaping is going to be very very hot. If your priming valve is hot, then it's flowing backward through the priming valve (which should have a check valve on the outlet) and possibly the pump as well, though the brew boiler's flow probably won't build enough pressure after the priming valve's checkvalve to actually close the priming valve. Anyway, you know the problem, feel the route of the escape. If it's the expansion valve, same thing, the temperature of the hoses is your evidence.

Zachary37 (original poster)

#4: Post by Zachary37 (original poster) »

Thanks for your replies. After it was mostly cooled off from this morning I ran it up to temperature again, but it didn't have syphon issues. I did open the steam wand during warm-up and nothing happened.

After I turned it off I noticed a small drip or two coming from the junction of the nylon and brass, pictured here.



It only dripped a couple of drops, and I've never seen any water pooled under the machine, so I don't see that as a big problem. But I should likely tighten it.

Lastly, is there a link to a diagram with parts names? It would be helpful if I could identify what I'm looking at/for inside the machine.

Thanks!

Zachary37 (original poster)

#5: Post by Zachary37 (original poster) »

My wife wanted a coffee this afternoon, which made it possible to try to diagnose again. I think I have it traced.

The water is escaping the smaller boiler out the lower port, through the t-fitting pictured. It is travelling down and toward the pump.



From there it goes through the nylon fitting, into the brass fitting, and back to the reservoir through the silicone tube.



This is assumed, as these parts were hot and the others not so much.

So from here, what bit(s) do I replace, and what are they called?

Thanks so much,
Zak

jgood

#6: Post by jgood »

Chris Coffee techs are really helpful and they know QM.

Zachary37 (original poster)

#7: Post by Zachary37 (original poster) » replying to jgood »

thanks. I sent in a question over their chat- hopefully they'll be able to help out.

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JRising

#8: Post by JRising »

Excellent picture.


Both the Pump outlet and the Priming valve will have a Check Valve to prevent the water from flowing backward through them.

If you unscrew the damper from the priming valve and look inside the outlet of the priming valve, you'll be looking at the plastic circle with a cross in it(Exact same set-up as the check valve in the Ulka Pump outlets). That circle can be unscrewed out of the outlet and the little rubber knob on a spring will come out. The little rubber knob is probably mashed out of shape and that's why the knob nop longer blocks the seat and the water is flowing backward through your priming valve. If it can be cleaned and reassembled to prevent you blowing backward through the valve, then it may be fixed. Probably best to replace it if the rubber knob looks beat-up.

Lastly, the reason some threads are exposed between the damper and the priming valve is because if it is screwed in too far, it will push the plastic circle all the way down on the spring and hold the rubber closed, the machine would get no water. Be sure to get some teflon tape on the damper's threads when you reassemble everything so that the valve isn't squashed but the threads don't allow any leakage.

Zachary37 (original poster)

#9: Post by Zachary37 (original poster) »

Thanks so much John! I was able to get time to inspect it this afternoon. Here is a pic of the plunger. Since I don't know what they look like new, how does it look? It was a chore to get that little guy in focus.


Zachary37 (original poster)

#10: Post by Zachary37 (original poster) »

A quick follow-up. I put everything back together the way it was to see if the check valve would reseat itself properly. It worked fine that afternoon, but by morning it was an issue again.

I ordered a new valve and it arrived yesterday. I replaced the old valve with the new one, and after two on and off cycles of the machine, everything seems to be working as intended. I'm willing to say it's fixed.

Thanks all for your input! I really appreciate it.