Quick Mill QM67 Flow/Pump Help

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Screamsi

#1: Post by Screamsi »

Hi everyone,

Long time visitor here. I've benefitted from the many helpful discussions on the forum, but now (unfortunately) it is my turn to ask for help and guidance.

I've got a Quick Mill QM67 that is having flow and pump issues. When I begin to pull a shot, sometimes no water will come out of the e61. I have to stop and begin the brew process a second time. Once it does get going again, the flow is really slow. The brew pressure seems to be pretty stable, but it reaches max brew pressure really slowly. Almost as if the pump isn't working properly.

You can see the issue in the video below.
I've performed the following in order to correct the problem, but after every fix the issue returns after the 3rd-5th shot:

1. I replaced the pump with a new unit
2. I took it to an espresso tech that - adjusted the expansion valve
3. Took it back to the espresso tech that then said the pump was missing a spring? (which he said he fixed)
4. Not trusting the espresso tech, I completely disassembled the e61 group and replaced all of the gaskets along with new valves (all three)
4a. There was very little scale (none really) in the mushroom or any of the e61 sections, but I still descaled in white vinegar.
4b. Checked the e61 gicleur (spelling?) for obstructions and there were none.
5. Fully descaled the machine twice (all day process)
6. Inspected all lines for leaks (vacuum/water)
7. Inspected and cleaned the steam boiler water level probe (I know it wasn't the cause, but I figured it couldn't hurt to clean since the machine was open)


At this point I'm ready to send it to another espresso tech because I'm out of ideas. Usually the first and second pulls after each repair tasted pretty good, but soon enough the issue returns. When a shot pulls cleanly, I'm still getting a pretty bitter coffee flavor - so something is still off. I tasted the water from the group and it tastes good - no descale flavor. Same thing with steamed milk. I've tasted it by itself and it's fine.

I'm thinking it may just be a faulty pump (even though new?) and I can purchase another. Other than that, maybe an obstruction in the lines to the e61? I don't want to start removing copper/brass fittings unless you all feel pretty certain where the obstruction may be.

Any feedback ideas would be greatly appreciated. Thanks is advance!

-Ulises

Jeff
Team HB

#2: Post by Jeff »

There's usually a filter at the end of the water pick-up tube in the reservoir. Is that completely clean?

On the bitterness, assuming the coffee has a flavor profile you like, I'd check the temperature offset in the display. The "flash boil" test is pretty easy and doesn't require expensive tools. If you're off by more than a couple degrees F from local boiling point, that might be worth tweaking.

Personally, I preferred coffee extracted at a slightly lower pressure in my E61. I ended up somewhere in the eights into a blind basket, as I recall. One thing at a time, but that might be some of the overall solution.

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Screamsi (original poster)

#3: Post by Screamsi (original poster) »

I'll calibrate the temp based the on the flash boil test you suggested. I've never calibrated with that method, so I hope it helps with bitterness.

As far as the particulate filter in the tank, I did remove it and test the machine with and without it and it made no difference.

My biggest concern is the no water or pressure coming from the group at times. When it does happen, I let it run for 30 seconds or so and I get nothing from the group. I think I recorded a video of that, if I find it I will upload it.

-Ulises

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cafeIKE
Supporter ★

#4: Post by cafeIKE »

If there was a spring missing from the pump, it would not work at all.

Temperature is not an issue with the flow. On a double boiler, the boiler temperature is set by the controls.

With the steam boiler OFF on a cold machine:
with no basket, what is the water debit [now much water flows out of the group] in 30s?

with a blind basket, what is the water return to the tank in 30s? Should be the same volume as group water debit.

Repeat with a hot brew boiler.
Repeat with steam boiler heating from cold.

There may be a bad connection that is causing the pump to have insufficient voltage. Are there any nasty looking discolored connections?

Screamsi (original poster)

#5: Post by Screamsi (original poster) »

I tested it this morning with the machine hot.

6 oz in 30 sec. from the group.
approx 5 oz. in 30 sec. from the return to the tank


I will test with the machine cold in the evening and update with those results.

It may be a bad connection because a few of the plastic sleeves for the contacts are discolored. I will try replacing those during the week. Do you guys know where we can purchase a new pack? Home Depot? Amazon?

Thanks again for the help!

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cafeIKE
Supporter ★

#6: Post by cafeIKE »

some discoloration is normal. When they are dark and brittle it's a problem.
photos?

6oz is ok, 5oz return seems about right

Pressino

#7: Post by Pressino »

This really sounds like a faulty 3-way solenoid valve, so that would be my guess.

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cafeIKE
Supporter ★

#8: Post by cafeIKE »

Could be, but we need to find out if it happens after a 3-way valve operation. Hence, step by step suggested.

Screamsi (original poster)

#9: Post by Screamsi (original poster) »

Ok,

I just got done testing, and the connectors don't look too bad (pics below).

Cold:
6.5 oz. in 30 sec. from the group
4.5 oz. from the return

Steam:
I wasn't sure how to test heating up from cold. Water would not come out of the steam wand until steam pressure was building and even then it was very little water - mostly steam. The hot water spout seemed like too much water - once steam was building.

I'm attaching a couple of images. First, the contacts to and from the pump. The other pictures are the only solenoid valve I could see. I believe that is the fill solenoid valve, not the three-way.

Is this the correct 3-way valve for my machine?
https://www.chriscoffee.com/products/qm ... -opv-combo

- Ulises






Giampiero

#10: Post by Giampiero »

Maybe the check valve fail and as consequence even the priming valve, so in stand by some water flown back to the reservoir from the coffee boiler and while the pump is activated the priming valve keep open too long slowing down the pressure development.
My 2 cents thought.