I have long been convinced that it is a good idea for HB users to communicate their methods for other users to ponder.

The MCAL is, in my opinion, one of the best constructed lever machines available today. When properly maintained they should last for many many decades. These machines, however, can be easily damaged by failure to take certain precautions. Here are things that I do to try to keep my MCAL in top working order:

1. External group examination: The lever pivot roller can seize and then slide instead of roll. This can do serious damage very quickly. This problem can be eliminated by proper lubrication and by taking care to watch with every pull that the roller is actually turning!

2. Internal group service and examination: Chloride containing water can cause serious damage to the group walls because the top of the piston runs "dry". Other nasty components of water can also cause damage. Chloride containing water in the pores of the brass evaporates leaving the chloride behind. As time goes on chloride concentration in these pores increases creating the possibility of "bronze disease", a chloride catalysed air oxidation somewhat equivalent to rusting. Instructions have been given in HB and other places about how to service and lubricate the piston. Each time the group piston is removed the walls of the cylinder should be examined carefully for pitting, and it should be cleaned very carefully. (One should do this even with chloride free water.)

3. Internal boiler flush and examination. It is a bit difficult to examine the inside of the MCAL boiler because of the small diameter cap. The best way I have seen is to obtain a rifle bore examination LED lamp. I follow the following procedure. (a.) Make sure the boiler is filled completely. (b.) Turn on the machine and allow to come up to pressure. (c.) Enjoy a cup of espresso made with it like this! (d.) DISCONNECT THE MACHINE from the power!!!!! Do this while fully "up to temperature." Immediately do the next step. (e.) BE SURE step d was done!! Put a bowl under the group. (I put the portafilter without a basket in place.) Push down the handle and hold it down and allow as much water as possible to be drained from the machine. (f.) Remove the cap and tip the machine over a bowl to drain out the remaining water. (g.) Fill the boiler with tap water and drain by dumping as in step f. Do this at least twice. (h.) Take a rifle bore light and insert it in the boiler cap threads. Examine inside of the boiler very carefully. Note condition of walls and element. (i.) If there be scale present, descale. Examine carefully to be sure scale is gone. Consider using better water in the future, especially if the scale be heavy. (j.) Refill the machine.

It is convenient to do a boiler flush and examination each time the group is serviced and lubricated.

rpavlis wrote:3. Internal boiler flush and examination. It is a bit difficult to examine the inside of the MCAL boiler because of the small diameter cap. The best way I have seen is to obtain a rifle bore examination LED lamp. I follow the following procedure. (a.) Make sure the boiler is filled completely. (b.) Turn on the machine and allow to come up to pressure. (c.) Enjoy a cup of espresso made with it like this! (d.) DISCONNECT THE MACHINE from the power!!!!! Do this while fully "up to temperature." Immediately do the next step. (e.) BE SURE step d was done!! Put a bowl under the group. (I put the portafilter without a basket in place.) Push down the handle and hold it down and allow as much water as possible to be drained from the machine. (f.) Remove the cap and tip the machine over a bowl to drain out the remaining water. (g.) Fill the boiler with tap water and drain by dumping as in step f. Do this at least twice. (h.) Take a rifle bore light and insert it in the boiler cap threads. Examine inside of the boiler very carefully. Note condition of walls and element. (i.) If there be scale present, descale. Examine carefully to be sure scale is gone. Consider using better water in the future, especially if the scale be heavy. (j.) Refill the machine.

Thanks!
What is the benefits of the hot boiler flush+examination? Why not just do a cold water dump+examination?

The benefit of any boiler flush is to remove the concentrated contaminants in the water that is in the boiler. Drawing steam off of the boiler to steam milk or just vent off noncondensible gases results in concentrating the remaining contaminants and this is cumulative until the boiler is flushed. Contaminants in the water are not carried out of the boiler in the steam, they stay in the remaining liquid. Doing this hot tends to get more contaminants out of the boiler.

Hmm ;o) maybe a hot boiler will be dry inside , easier to inspect ;o)

Ps , one can buy a cheap usb endoscope that has its own light source, they are even watertight (they claim)

What about the chlorine in the bore , would it be a good idea to wash it out?? put a small plug in the inlet hole , put on portafilter with blocked outlet, and fill up the cylinder with water and let it stand for some time

Boilers and/or steam generators are not blown down cold as some things you do not want in there drop out of solution when cold.

Is there any difference in maintenance requirements between the chrome and brass group heads? How about the chrome and brass boilers?

Depending on how they were chromed the insides of things may or may not be chrome plated. I suspect most machines are not internally plated? One can determine this by simple examination.

External chrome surfaces need to be kept clean and dry. All MCAL bases are plated, either chrome or copper over steel. One must not allow water to collect under the drip tray!

Maintenance requirements are dictated by water chemistry. Brass or copper boilers have been around for a long time and if used with distilled water they require minimum periodic maintenance. Just about anything else will require different water chemistry control procedures based on the exact chemical/mineral makeup of the water used. I believe rpavlis has several detailed posts on water chemistry., they are definitely worth the read.

I suggest you remove the piston assembly from the group head for a thorough inspection and cleaning. It is amazingly easy to do this--just remove the two Allen screws on top and pull it out. Push out the dispersion screen with a flat, preferably wood object, and clean the bore very carefully. I often use brass polish on mine when I take mine apart. Be sure to wash away all traces of brass polish after doing this. I also usually finish off by wiping the bore with grain alcohol. Lubricate the piston seals with the standard Dow "silicone". Put plenty on the upper piston seal, but do not over do it with the lower one, or it may clog the holes in the dispersion screen. Use care not to damage the seals when you re insert the piston assembly into the group body. Push any silicone that ends up on the top of the bore back into the bore when the seals have been reinserted.

What you do not want to see is pits in the cylinder wall.

You might flush and examine the inside of the boiler too, as described at the start of this thread.

As I pointed out before, the MCAL is particularly sensitive to bad water, because the cylinder walls above the piston are open to the atmosphere and dry out, concentrating contaminants there.

These machines are built to last for decades and decades unless abused by failure to clean things or use of water with the wrong contaminants. Distilled water does not have contaminants at all, and is fine, though water with about 100 ppm potassium bicarbonate or sodium bicarbonate allows a better protective film of copper oxides over the brass and copper parts. It also reduces acidity of acid coffees, and results in a flavour shift. The flavour result is very similar to weakly hard water that is otherwise clean.