I am reconditioning a La Cimbali DT1 of unknown repair history http://www.home-barista.com/espresso-machines/plumbing-la-cimbali-jr-and-other-questions-t11178.html and everything was going fairly smoothly until I attempted the first backflush.

Using a triple basket (it's all I have at the moment) and a blind rubber insert, I cycled Joe Glo a couple of times (approximately ten second on/off intervals). Nothing came from the three way, except perhaps a single drip, and eventually there was an overflow from the group gasket. The machine pressures up fine, water doses appropriately through the grouphead as well as steam and direct water. A boiler and hx descale have already been done.

I took apart the solenoid group. There was a little bit of grime, but the path was clear. I cleaned and reattached the solenoid group and still no joy. I have not heard a *click* from the solenoid, though, I must confess that since most of the sounds of the machine are so new to me, I may not have an ear for such things yet. I have not messed with the opv, nor put grounds in the portafilter yet.

Paul Pratt's page and others have been fairly instructive on the need for solenoid replacement and testing, but I'd like to get the specifics of how to troubleshoot this item. I'm not afraid of a voltmeter so long as I know where it is being attached. Any suggestions before I run out and buy a new coil and/or valve? Is it possible that the depth of a triple basket is preventing the 3-way from opening properly? I would think that that might be a volume left in the basket issue, but the pressure itself will eventually rise to the necessary level to do the job.

Thanks

1. With machine turned off - measure the resistance across the coil.
2. if the reading is open, replace coil
3. if reading is not open, measure the voltage at coil with machine running (is either 24vdc or 110/240vac depending on your model.
4. if volts ok and coil ok but not clicking the body is jammed. Replace
5. if volts not reading - hmmmm. Check wiring connections. I don't think these have a fuse for gr solenoid. Panic. (I don't think this reason is very likely)

Thanks Paul. Just what I was looking for.

When the three way valve is not energized (ie at rest) the path from the brewhead to the backflush port should be opened by the force of the internal spring inside the body of the valve.

When you flip the brew switch on the current will flow to the coil and force the valve to close the path to the backflush port and open the boiler port to allow water to flow to the head. Once you shut off the brew switch the spring should force the boiler port closed again and allow the water to flow freely once again to the backflush port.

If you do not get any release of pressure when the brew switch is shut off either the spring is not doing its job, or the opening of the backflush port in the valve is being blocked by something. If that is the case tear down the valve body and take a good look at things, and descale it while you have it ripped out.

Good luck!

-Cecil

Well, now I'm back at square one. The solenoid coil showed a closed circuit at rest, but I wasn't able to get any voltage across the plug. Nor can I feel a click on power up with my hand on the coil. However, water travels from the HX to the grouphead without venting to the drain which means the valve is closed. So either I'm doing something wrong or there are TWO failures in the system- not very likely unless someone did it intentionally as a "fix". I can't see any obvious mechanical problems with the valve body, so I suspect the easy answer...I'm doing something wrong. I'll likely start testing the individual wires for voltage to see if maybe there is a loose wire or a bad connection in the main switch where these lines aggregate unless there is a different idea of what to test.

At least this is a fun machine to work on. Reminds me of old mustangs with everything obviously laid out and accessible.

Thanks for the help.

Hmmm. So, looking at your first post; water comes out of the gr when you run the pump? But your 3way sol is not working. Your coil is not blown but not getting power. If water is coming out, then the sol plunger must be in the open position (ie, stuck open or very bad seal at the end). On a non-plumbed machine this will mean you can make coffee. On a plumbed machine, water would be exiting the hx as soon as the mains pressure went on. Ohhh - but you've got one of those guys with the plastic reservoir so you won't have this problem.

Hard to say what is wrong. If it were in my workshop I'd be looking at why there was no power to the gr sol. Specifically, I'd look at the relay function on the main board. After this was sorted, i'd probably replace the gr sol body rather than attempt a repair/descale.

thanks again. This machine does have a plastic reservoir thing, so making espresso can still happen despite the issues with the three way. Just a soupy puck, right? I'll likely do as you suggest and look back at the relay to test juice at the terminals. That will give me some answers. Meanwhile, I'll look at the valve body again to make sure I haven't missed something obvious.

It's still a week before the grinder shows up, so I have more tinkering time to track down the mechanical issues.

Junior wrote:I can't see any obvious mechanical problems with the valve body, so I suspect the easy answer...I'm doing something wrong.

I want to be clear when you say that you can see no problems with the valve body.

If this was a visual inspection of the valve body it may not tell you what you need to know...


To see the problem I was speaking of you would need to remove the head/shower screen/three way valve assembly from the boiler and the body of the machine, then remove the 3 way valve from the head, then remove the coil block from the valve body. Then finally split the mating halves of the valve body open and check the condition of the ruby seals and the seats that they seal against.

Or you could try blowing into the backflush outlet pipe with the power off and see if you can hear air easily flowing out of the grouphead, if not do the above and descale everything in the group head path.

My guess is that you have scale blocking the lower outflow port of the valve or the sliding part of the valve is hung up on scaling. ESP if you tried to descale the HX/boiler and could have flushed any gunk down the line.

Bumping myself, sorry.

I did think of one other thing. When I had my machine apart the 3 way would not come clean with the descaler, the coffee oils in the backflush port had become rock hard tar. I had to soak in hot a Cafiza bath for a couple days with firm scrubbing from a scotch bright pad to get that build up to come off, but in the body was a nice bright pink, and the main valve and spring were smooth, shiney, and free.

I swear that stuff is worse than a mineral deposit to get off.

-Cecil

Interesting. I did take the rod and spring completely out of the valve, just to see what basically a straight tube would do. Most water came down the 3-way vent, some went out the screen.

I'll try the blow method and see what that gets me. I'll take it apart regardless, but this will give my family plenty to laugh about.