La Marzocco Rebuild - Part 1

Go to part 2 of the rebuild

Click pictures to see an enlarged version.

Finally, my La Marzocco Linea arrives. This unit had a shipping weight of 220lbs.
Included on the pallet was the main unit, a pump motor, and a pump. It was also supposed to have 3 portafilters, but those were back ordered.
It took me a few days, but before long I decided I was going to tear the entire machine down and rebuild it.
All three of the solenoids have this gray film on them. I tried to scrub it off, but it is actually in the plastic, almost like oxidation.
You can see some scale buildup. The gaskets were also shot. You can see part of the fiber gasket sitting in the group.
This unit has an old style brew boiler in it. This type of boiler uses 8 brass captive nuts held inside the boiler by a stainless steel mounting plate.
The boiler looks pretty good inside other than a little build up on the nuts.
You can see a wire binding post tree hanging at the bottom right of the picture. I think these should be held in by bolts and nuts, but there was only a small sheet metal screw inserted that wasn't really holding.
The front of the machine as I am removing all the components from the case.
A close shot of the tear down in progress.
As I removed items from the chassis, I placed them on a moving pad on top of the pallet the machine arrived on.
This is a close up of the brew boiler with all the groups, thermostat, and pipes removed. You can still see the heating element inside.
Any smaller parts were put into a box to await cleaning.
I labeled all the plumbing as I removed it and put it on this table.
Showing some build up by the banjo tube in the group head.
The group gaskets and o-rings were fossilized on this machine. I had to use the diffuser tool and a breaker bar to remove the diffusers from this machine.
I unfortunately broke one of the banjo tubes while trying to remove the bolt. They are silver braised together and I could have repaired it, but I decided just to order another one.
The one on the right has had the banjo tube and diffuser removed.
In order to descale all the plumbing I soaked it in a citric acid bath.
In order for the citric acid to work it has to be hot. I have heard that the best is around 150 degrees.
The first time I did this I put boiling water into the tub, added the citric acid, then the parts.
This worked great at first, but by 7 to 8 hours later the water had cooled leaving the parts looking worse than before I started.
In order to keep the solution hot I made this contraption. There is a small pump in the bucket that pumps water into the flask where it is heated on the electric skillet. With a rubber cork in the top of the flask you have a closed system and any water pumped in causes the same amount to be forced out.
This system worked great! It keeps the water hot, and it also created some current in the water to keep things moving around.
The flask doing its job.
This was hot enough to do a good job descaling the parts without damaging the plastic pump.
I didn't degrease some of the parts enough and so they were still a little dirty.
The citric can't eat through the grease so you have to be sure your parts are very clean before you start this process.
I also ran a metric tap into each one of these nuts to clean out any rust or buildup.
Comparing the citric acid bathed captive nut to another one that has been polished.
Parts cleaned, polished, and ready to start reinstalling.
I could not descale the boilers in my small device so I had to enlarge it.
I used the same pump. I purchased an electric hot plate from a local hardware store and a plastic bin.
The original flask I had was small and cheap. It apparently could not deal with the heat differential of this new setup and shattered near the bottom minutes after beginning.
I dried everything and moved up to this actual Pyrex flask. It is larger and thicker, and works very well.
A top down view of the larger process in action.
A bit cooler at the beginning, but after 12 hours it had gone up to 130 degrees.
Ready for polishing.
The brew boiler came out great! I could not be more happy with this result.
Another shot of the brew boiler after cleaning.
All the second round parts laid out neatly on my work bench for inspection.
The three groups cleaned up nicely.
The group tops, and bayonet rings cleaned up well also.
The scale seems to have removed the nickel plating from the groups wherever it was thick.
You also have to be careful not to leave these parts in the citric bath too long or it will eat away the nickel plating
You can see where the scale removed the plating on the group top also.
I used a course wire wheel on the brew boiler, and I am pretty happy with the result.
You can see the result a bit better in this picture.
The heating element side of the brew boiler.
The brew boiler with the captive nuts, thermostat tube, and the drain plug reinstalled.
Here is a close up of the captive nuts reinstalled in the boiler.
This is a picture of the inside of the brew boiler taken through the heating element mounting hole.
You can see the thermostat tube and the captive nuts at the top.

Go to part 2 of the rebuild