Group Head Gaskets... FROM HELL

Once again, the accurate and impassioned knowledge of the CoffeeGeek and Home Barista community taught me two things.

1. Group head gaskets should be replaced every 6 months as part of regularly scheduled maintenance.
2. If group head gaskets have never been replaced on a machine nearly 20 years old, and the rubber composite has been subjected to repeated onslaughts of heat, water, and espresso residue, you will create a fossil.
3. Fossils are neat when you're 7 years old; they suck when they have integrated themselves into your espresso machine.

I didn't even know how deep this gasket went nor where the gasket started and the espresso residue funk on the underside of the group head ended. The gasket was literally as hard as the surrounding brass. I made my inaugural post to the Home Barista forum to be met with great advice with a slight "oh you noob" undertone. Aside from the newbie chiding, I got my answer on how to remove the gaskets, but the execution was where the real challenge began.

I tried using a spoon like their example showed, and then moved on to the church key (paint can opener). Not getting anything other than frustrated, I ventured out to Lowe's in search of the dentist pick set I heard they had. I finally found them after a lot of searching and store employee assistance, and brought them home to beset upon the gasket fossils of terror. $6 and two bent picks later, I decided to try the wood screw approach. I had to use a power screwdriver on low torque and drilled the screw into the gasket. I pulled on it with some needle-nose pliers and the screw came out bringing with it only as much fossilized rubber as the threads had touched. I tried again and again only to leave the gasket slightly pockmarked as if attacked by a persistent, yet retarded woodpecker. It was time to break out the Dremel 4000.

I had to be very careful not to go too deep or too close to the sides as the group head brass was at risk of being deeply gouged, and aside from aesthetics, it could compromise the seal I was desperately trying to restore. I used the smallest engraving bit I could find, and after securing the group head in a vice padded with towels, I started creating a small crater in the fossilized rubber. Afraid to go too deep, I then began prying with a small bladed screwdriver in the crater and managed to work deep enough that the rubber separated. I tried again a few centimeters back from the split, but I had to use a hammer to gently increase the depth of the blade. It finally popped through and broke out a chunk of the fossilized gasket. I had a brief moment of celebration, and then kept chipping away chunks until about 20% of the gasket was out. With a little leverage, I worked the screwdriver under one of the exposed ends and pryed the rest of it out.

Now knowing the process, I was able to get the second gasket out with much more ease than the first. The shower screens on both were in decent shape, but despite soaking and scrubbing with the brass brush, I couldn't get all the gunk out of the fine mesh. After a quick search on Cafe Parts, I decided to replace them both when I replaced the gaskets. It was definitely worth $7 each.

Now that the hard part was over, I still had the task of cleaning and descaling the group heads. I removed the shower diffuser screws and the pre-infusion chamber as well as all the internal springs and pistons within the group head. I found an exploded view of the E61 group head, and took it down to the most basic parts I felt comfortable doing. I reused some of my original acid bath that I saved in a 2 liter coke bottle, and soaked the brass parts overnight. The chromed group head components I just let soak for 10-15 minutes to prevent problems with flaking or discoloration. As the underside and internals of the group heads are brass and don't have the chrome plating, I turned them upside down and filled them with the citric acid solution to make the residue easier to remove and break up some impressive calcium deposits where the hot water pipe inputs were located. With two group heads, it was pretty easy to get a before and after shot of some of the parts, such as the shower diffuser screws. Black vs. Brass.















After the inverted acid soak, I did the best job I could in scrubbing out the grime inside the group heads with the wire brush and shop rag. My main goal was to remove any remnants of rubber that may have sealed to the brass, and to get the loose espresso reside off to prevent off-tastes when I finally got it up and running. I could have probably spent more time cleaning it up to remove the discoloration, but I think functionally, it is good to go.

The steam wand, steam valves, and hot water dispenser were also cleaned during the group head process, but I think they deserve their own post. Stay tuned for my next post: "Steam Punk, Milk Funk".

Interlude: Shoot often or get screwed

I realized I didn't really cover the organizational aspect of this rebuild in too much detail, so I thought I would made a quick post to comment on how not to turn what was a fun and challenging project, into a junk yard nightmare.

The camera I used was a basic 8MP Canon Powershot 850IS. Nothing too fancy, but it got the job done by photo-documenting the tear down and general construction of the machine. The key was to take a wider shot of the machine from several angles of the parts to be removed, then switch to the macro setting (which looks like a flower) and get detailed shots of each piece you remove in the order you remove it. For the long skinny tubing that disappeared behind the frame wall, I took shots of both connection points one after the other so I would know where to put it back. The great advantage of our wonderful digital camera age is the nearly unlimited quantity of photos you can take with nearly instantaneous feedback on quality and framing of the shot. From inception to completion, I took 613 pictures of this espresso machine and it's assorted parts. They were worth their weight in gold when I began reassembly.

Apart from the symphony of brass nuts and copper tubing performing an aria of mechanical exhibitionism, there are a lot of nuts, bolts, washers, and screws inside a machine this size. Thanks to my pack-ratted-ness and frequency of breaking bicycle parts, I had several small zip lock baggies perfect for storing associated hardware. The snack sized zip lock bags would have also worked, but I was too lazy to go to the store. I also used a cheap plastic fishing lure divider with a snapping lid that I found in my tackle box. This allowed me to either label the bags or drop in the divider a post it note describing what the screws, or bolt assemblies belonged to. When I was reattaching the group heads to the frame, I just grabbed the bag labeled, "group head hardware" and reattached it. Same with the "pump motor mount nuts", and the "power box screws". Organization on the front end will save you screaming and hair pulling on the back end, unless you know... that's your thing.

Next post, I promise... the group head gaskets from hell!