Sunday, 17 June 2012

LeLit PL041 OPV Fix

A friend of mine was having some trouble with his Le'Lit PL041. It's about 1.5 years old and has not seen much maintenance (no descale for even backflushing). Recently he told me he started hearing strange noises from the pump where it would go loud and then quiet, and the pressure gauge was swinging from 12 to 6 bar.

I like tinkering and learning about different espresso machines, so I agreed to have a look to see if I could fix it.

I must say, I heard good things about this Le'Lit. Folks on forums tend to recommend it a lot over other "single boiler- dual use" darlings  of the past (like Rancilio Silvia which is about $300 more expensive). My feeling having used and stripped both these machines is: you get what you pay for. The Silvia is definitely a  better made machine, no doubt. Thicker gauge steel, more robust components, less plastic bits, etc. Defintely worth the extra cash. But if your on a tight budget, the little Le'lit is not a bad choice.

Well, back to the problem at hand....

A swing in pressure makes me suspect 2 things: pressure source, or pressure oulet. In other words; pump or OPV (didn't seem electrical to me so I ruled that out) . While the suspect part could be either, the source of the problem is almost always the same: scale. So my fist step was do a good chemical backflush followed by a descaling with citric acid.

The descale seemed to change the rythm of the pressure swings. In fact, I even got one shot that didn't have the pressure swing. Still, it always came back.

After a few days trying with e-mails, I realized that the store where it was purchased (Idrinkcoffee), is not much into replying to e-mail. So after a few phone attempts, I finally got hold of the tech. He listened to my story, asked if I descaled, and told me it was either the pump or OPV, but he had no parts available to replace either. Hmmmm. Not much help.

So since I was pretty much on my own, I decided to just dive in:

Here's a view with the top off looking down on the boiler:

I was quite surprised to see the layout. The wiring and plumbing was a lot more complicated than I imagined after having worked on my Silvia (installing a PID). The water seems to go through quite a complicated flow path to get to the group head as you can see in the photo below:

The water starts at the Ulka vibe pump (1) then goes all the way around the boiler to the opposite side where it hits the tiny, non-adustale OPV (2). The water then enter the boiler, only to exit again out the other side, past a solenoid (3),  it then gets routed BACK through the center of the boiler into a "mini HX-like" brass tube (4), which passes straight down to the group head. Phew!

The boiler is rather small but with a powerful heater, and it sits directly over the grouphead. This means it gets up to temp VERY quickly and the groupheads stays nicely warm and stable. The problem is in the water path. There are sections in the water path where the water is cold (like just after the solenoid) and areas where it is super hot (like in the brass tube in the boiler). I noticed this when I did my first shot where the water first came out almost as steam, then after about 3 seconds, cooled right down to a proper temperature. Funny thing, I find myself doing 1 oz "cooling" shots with the Le'Lit and 1 oz warming shots of the "cold nose" on my Vivaldi. I just can't win!

Anyway, back to the problem at hand:

As you can see in the photo, the OPV is covered with a mess of wires, so I figured I'd start by removing the easier to access pump, disassemble it, and make sure everything looked normal. It strips down pretty easy (it's a brilliantly simple piece of engineering actually). The tiny plastic check ball and springs looked unworn and clean, so I quickly reassembled it and started work on the OPV.

I had heard the OPV was "Loctited" so that it could not be adjusted, so I was a bit worried to start. But in fact, the Loctite they use is very weak, so the screw turned easily. I rcarefullly removed the tiny spring and valve seat from tube with tweezers.

As soon as I saw the OPV valve seat, I suspected I had found my problem. The soft, green valve seat is stuck into a copper nut, but the nut sides where rusted and scaled up, likely restricting free upward movement in the brass valve body:

 A quick soak in citric acid:

 Then some food grade lube, and they looked as good as new:

I used my "neuro-surgeon skills" to wrap some teflon tape wround the adjustment screw so that it would not back out under vibration with the Loctite now removed. That's a pin next to the screw that I used to clean scale from the hole in the center of the screw (see what I mean by small!) The adjustable OPV in the Silvia is huge in comparison.

I reassembled the OPV and checked the pressure on the gauge with a blind basket in place. No more pressure swing! The pressure was high at first, but after a bit of tweaking (it is rather sensitive which is why I suspect they lock it), I got it right at 10 bar in the middle of the green zone (it was at 12 bar before).

This is a much better pressure for this machine, in my opinion. In fact, having now disassembled the OPV and seeing how easy it is to to make adjustable, I wouldn't hesitate to recommend this on any machine as an improvement.

Thursday, 18 August 2011

Mini Vivaldi Brew Boiler Descaling

I started this overhaul with the intent of getting inside the brew boiler to see if any scale had built up over the last 2.5 years.

After about 1.5 years, I added a descaling solution to my reservoir to descale the brew boiler, but since I can't see inside, I was never sure it removed everything. At the same time, I inspected my steam boiler by removing the vacuum breaker and looking inside with a flashlight. Everything looked clean there, but since I use the steam boiler only on demand, the brew boiler gets about 10 times the use (or about 2 hrs per day using my timer).

The first step to opening up the brew boiler is to remove the large lugged brass nut. You could use a "adjustable hook wrench" if you happen to have one for adjusting motorcycle shocks, but since I didn't have one, I simply used a piece of wood and hammer to get it turning. The wood helps prevent breaking off a lug if hit directly with a hammer. I could have also wrapped it in a towel and turned it with a large wrench, but there is not much room so the the wood piece seemed like the best method(which worked very well after a few light taps).

The nut came into contact with the heater tabs near the end of turning, but the tabs bent outwards slightly and the nut came right off exposing the back plate of the heating element. The back plate was still stuck against the boiler, so no water came out, but I put a yellow cup just underneath for when it started flowing.

To get the heater out, I needed to pry the backing plate away. WARNING: There is a small anti-rotation pin on the backplate, so don't try twisting it off. Instead I found another method that work extremely well. I took an old chisel and tapped down lightly into the gap at a few loactions to gently pry and work the plate away from the boiler (and the water started coming out like CRAZY). Next time I do this, I'll roll the machine onto its front at this stage (before removing the heater element). That way, the water will stay in (until I syphon it out), and descaling will be much easier as well.

There is a black o-ring in a groove on the outside edge of the back plate as seen in the photo below. So be careful not to cut it if you use the chisel to wedge the back plate away. Also, don't use the chisel from directly on top, since you might contact the small anti-rotation pin inside.

Once the heater breaks free, the water begins to come out (so be ready with a big cup....bigger than the one I have here... which overflowed).

NOTE: For re-assembly, it's a good idea to lube up this critical o-ring with Dow 111 food safe valve lubricant & sealant which you can buy from Doug & Barb at Orphan Espresso:

What came out of the boiler was a TOTAL surprise. I expected clean water like I found in the flowmeter, but instead I found a gross, milky water with small white particles floating around.....YUUUUCH!

What is this stuff you ask? Scale? Nope... I had seen this once before when I had changed my filter. This is the stuff that comes out of the water softener cartridge after it's used for the first time. I had just installed a Rancilio Silvia softener, and the resin (which is coated with NaCl for ion exchange softening) will appear cloudy like this at first use. I'm pretty sure it's not dangerous, but none the less, it looked totally disgusting.

Now how about inside the boiler? Well here's what it look like as I first opened it:

There were a few white lumps (scale pimples?), mostly on the stainless forward section of the boiler (not the copper back section). There were a few bigger soft lumps, but I assume this was softener resin. Whatever the large lumos were, they came off rather easy. The smaller bumps were harder to remove.

The the inside neck of the boiler (just inside the threads), appeard to be corroded at the bottom (as did the backing plate). The nickel plating had been eaten away, exposing the bare copper, but only at the bottom. I had seen this in photos of other machines that were stipped for descaling. My guess is that the heating element falls slightly when assembled and makes a light "point contact" between the brass backing plate and nickel plated boiler wall. This combination of water, metal, heat and charge seems to produce the perfect galvanic couple to produce corrosion. SO BE WARNED: For this reason alone, I'd recommend opening the brew boiler like I describe here every 2 years maximum, to check the conditon. When I re-assemble, I will likely lift the heater up before tightening the nut to see if this doesn't prevent the contact at the bottom.

The heating element had a thin, white layer of scale started. Not much. But enough to do some descling using a citric acid solution (1 teaspoon of citric acid powder for 1 litre of water).

After a 30 minute soak, it came out pink and perfectly clean.

I dipped a scotchbrite scouring pad into the citric acid solution and used this to scrape the inside of the boiler clean. I stuck it on the end of a wood rod to act as a handle since my fingers were not long enough.

After a bit of scrubbing and soaking for about 30 minutes, the insides were sufficiently clean (though not perfectly smooth). I thought about tipping the machine on its front and filling the brew boiler with citric acid, but the result I had with the scouring pad seemed good enough.

I then removed the vaccum breaker from the steam boiler and poured the remaining citric acid into the steam boiler. I removed the citric acid after 30 minutes using the "syphon method" shown in the photo. If I had a drain plug on my boiler like on the newer Minis, I would have used that, but the syphon works just great.

One other thing you might notice about the steam boiler from this photo. The flimsy, paper thin, white plastic boots on the wire terminals have all discolored to yellow from the heat on top of the boiler. (They are still white on the sides where it is cooler).  A very poor choice by the engineers on such an expensive machine. If I can find some higher quality "clip on" replacements that will withstand the temp, I might change them.

I'm now ready to puit everything back togther. Nothing special here so I won't bother posting photos (unless something interesting happens).

Sunday, 14 August 2011

Mini Vivaldi Flow Meter Disassembly

Except for a layer of dust, the insides look pretty new.
While I have it apart, one area I've wanted to take a closer look at is the flow meter.

Here's picture of the assembled flow meter:

This is a picture of the meter with the magnetic pickup removed. (You need to loosen a hex screw on the front of the meter to remove it. This is best left until AFTER you remove the 3 hex head cap screws that hold the black reinforced plastic cover onto the brass manifold on the bottom).

Here it is with the top cover off. Do this, you'll need to get a sharp chisel between the cover and the brass manifold to wedge it up and out (there is a tight o-ring seal inside to prevent leakage). Once open, you can see the small, white telfon vaned rotor that spins around. On top of the rotor are 2 metal inserts that spin past the magentic pickup above and produce the signal. Two metal passes correspond to one rotation and a fix volume of water. The white circle around it is a o-ring seal.
If you look closely in this photo and the next, you can see the hole in the manifold on the right where the water enters (just below the water line) and on the left is the exit hole.

In this shot the teflon rotor has been removed. You can see that the pin where the little rotor sits almost frictionless. Didn't seem worn, but if the rotor did ever wear out, it would be nice if you could replace the little $5 rotor (but I've hear you need to buy the WHOLE thing).

In this last shot, you can see the tiny rotor with my thumb next to it for perspective. The vanes are square, but I've seen some that have melted where they can appear almost rounded.

Mini Vivaldi Strip

Now that the Cremina is running smoothly, it gives me some time to strip my main Mini Vivaldi. Here's how she looks just before the strip:

It's been a fantastic Latte machine, and has performed flawlessly for the last 3 years when I bought it new. Still, I figured it was time to open her up and poke around inside. I figure I'll remove some caked on dust and at the same time, see if there is anyhting that needs my attention.

Mine is a 2009 Mini Vivaldi. It has a sealed boiler (drain was added in 2010). Even with no drain. it's rather easy to add descaler. But you can't remove the top like on the regular Vivaldis with the bigger boiler to "physically" remove scale (which is often required if the scale develops any thickness). I understand why they did this, since it saves space and also cost. So this means you have to be careful to use soft water (5 grains or less), to avoid too much scaled build-up. At the same time, I believe this whole "scale" issue is a bit exaggerated. After all, while I've used a water softener for the last 3 years, I've looked at the heater coils in the steam boiler after I've removed the vacuum breaker, and it looks perfectly scale free (copper colour coil). Still, my plan is not really to decale the steam boiler (since I can do this simply using a funnel and syphon tube and removing the top cover only). I'd like to get inside the brew boiler, since this is the most expensive part of the machine and has been "on" for at least 10 times as much as my steam boiler (which I only turn on for 5 minutes when making a milk drink). This ability to turn  on the steam boiler briefly "on demand" and be ready to make steamed milk in less then 4 minutes is what makes the Mini Vivadi the best home espresso machine in the world (in my opinion of course).

The top, front and sides all come off very easily with any screwdriver (now that the side panel design has been changed so they are held in place with easily accessible top screws). Here's what it looks like from the back with the covers removed:

That's all for now. It just got sunny outside so it's time to go bike an dplay with the kids. More stripping later!

Sunday, 7 August 2011

67 Cremina - Pulling the first few shots

The machine is now fully restored and sitting on the kitchen counter across from my Vivaldi. Time to pull a few shots.

The first one I pulled before the restoration was much too hot, so I dropped down the pstat to somewhere near midway as my starting point.

I turned on the machine and everything seemed to be holding together well. Only a small leak from the nut on the top rail holding on the steam faucet. For some reason a new copper washer was left out of my rebuild kit from OE. I needed to re-use the old one, but these are only one time use items. (By the way, I e-mailed OE and Barb sent me a new one in the mail right away...aren't they great!).

The machine warms up quickly (only 6 minutes until the heating light goes off!). I bled off the false pressure from the steam wand and then did 3 flushes with the lever to warm the grouphead. Only 8 minutes from on, and I'm ready to make a shot....amazing. (For comparison, my Vivaldi takes 40 minutes to get up to temp and stable). This is the fastest warming machine I've ever used, truly a "walk-up espresso" lover's dream machine!

I then ground 16g of Vermont Artisan Coffee "Espresso Blend" that was roasted 4 days ago (I picked it up myself from the roaster a few days before when I was at the Vermont roasting facility). I pulled my first shot, but it was cold and sour. Obviously I had gone too far in lowering the pstat.

I knew this machine would take some time to calibrate to the proper temperature. It involves quite a few subtle variables like warm-up time, number of warming shots, number of previous shots, etc. A moving target that would require me to gain experience first.

Luckily, I have a big advantage here in that I have a super accurate and consitant LaSpaziale Vivaldi sitting across from Ms. Cremina. So all it takes is to warm 2 cups on top of the Vivaldi, pull one shot from the Vivaldi, and a second from the Cremina. I then compare espresso temperatures (in the cup), with my probe digital thermometer, and I should be bang on. When set to a group temperature of 93F, the Vivaldi gives me a perfect 66C in the cup. So this is what I aim for on the Cremina. It only took 3 shots (3 seperate days actually), and after raising the psat about 5 turns higher, I was dialed in at 66C.

I attached my OE steam wand Omega pressure gauge and measured a pressure swinging from 0.8 bar to 0.95 bar. Seems good to me (from what I've read). I also read Olympia recommends 0.9 Bar.

So here's the current espresso shot process (using my Mazzer SJ grinder). Enjoy!

Monday, 1 August 2011

67 Cremina - Rebuild Time

So the boiler has now been removed and stripped of asbestos insulation. Now it's time to shine her up.

One thing I know for sure, I won't be using sandpaper like I've seen on other restorations. Sandpaper scars up the surface horribly (even fine grit). Instead, I'll soak the brass boiler in a ctric acid solution for a few minutes then rub it lightlly with a nylon scouring pad (NOTE: Don't use ANY citric acid on the chrome parts or it will strip off the chrome).

After the mild acid bath is complete, I buffed the surface using Simichrome paste. This stuff works like magic and creates a "gold" like mirrored surface on the boiler. The solder adds a neat "candle effect" I think.

I touched up a very small spot on the inside of the metal frame with Krylon "hammer surface" grey paint (a nice match).

All the remaining parts were removed from the frame (including every nut and bolt). All bolts were cleaned and lubed for re-assembly.

The grouphead was stripped entirely as well. The mini snap ring pliers worked really well for the c-clips!

Now time for re-assembly:

Despite the cleanliness and obvious lack of use of the machine, the rubber gaskets were all baked flat and cracked. Butyl rubber is temp rated to 250F and has a shelf life of only 15 years, so I'm WAY past due for a change! I replaced every gasket using the gasket replacement kit from Orphan Espresso. The new gaskets are silicone, rated to 500F and with unlimited shelf life . They should last MUCH longer and allow me to re-use them several times when I need to strip every 2 years or so to remove scale, etc.

Here's a picture of the old gaskets (on top) and the new ones (on bottom).

First was to install the boiler end plat gasket and reinstall all the wiring. Thank goodness I took a picture of the wiring before removing! I needed to refer to it several times. It then went back together perfectly.

Next was the most difficult part....restoring the group head. I chopped of all the old piston seals and soaked the brass portion in citric acid (NOT the chrome part though). Still, I needed to use steel wool to remove the black from the piston grooves.

On the inside walls of the group head chamber, I used steel wool, and then wet sanded with 400 grit paper in a circumferential direction to avoid and length-wise grooving that could cause slight leaking. (This is the only area where I sanded...since it cannot be seen).

I soaked the remaining chrome parts in Dusty Caf cleaner overnight. (This is a very mild soap used for cleaning portafilters and for backflushing and will not strip chrome).

Once everything was clean I installed the new piston seals with Dow 111 lube and did the upper rod cup seal as well. With a litle patience and poking, everything went together smoothly. The OE supplied rod end cap and instructions worked perfectly.

Here's how it looked when done:

The next step was install the sight glass tube and new o-rings. These worked VERY well. Only problem was trying to figure out how much torque to apply so it didn't leak but not so much that it would crush the glass. The trick seems to be to tighten it ONLY enough so it doesn't twist, then tighten more only if needed after the hot leak check.

The remaining items on the top rail, pstat, faceplate, steam faucet and grouphead all went on in about 30 minutes. The saftey OP valve was installed with a teflon gasket from OE. But for some reason the replacement copper washer for the steam faucet nut was missing (maybe they assumed mine was a post 1982 model?). In any case, I re-used the existing copper washer (which leaked but eventually sealed after some good tightening). I'm not sure why OE doesn't supply a teflon washer for this nut as well, but I suppose it is because the nut holds the steam tap from moving, so it needs to be a bit stiffer than teflon.

The new handle was installed as well. It looks great and appears totally original. (I'm very happy with that).

Not much left to do except test her out!

I pluged her in and crossed my fingers I got all the wiring right! Phew. No zap.

I added an Omega gauge to the steam wand tip with a rubber hose and checked the pressure. It was low but I increased the pstat pressure to get between 0.8 bar and 1.0 bar (quite a big deadband!).

Well that's it. Just added the back and top and here is the final result:

And another shot from inside showing the sexy boiler:

So what about the espresso you ask?

Well, I pulled a few shots and the first few were a bit hot ( I since dropped it down 0.1 bar). I also need a lot more practice. Things like warm-up time, warming shots, pre-infusion, dosing, etc, all make a huge difference. I'll report back with some espresso pictures after I've gotten a few more hours on her.

All in all, a WONDERFUL restoration experience. I can't imagine a better machine to start out with as a first project, since everything is simple, easily accessible and most parts you can get from Doug and Barb at Orphan Espresso (along with their free, excellent advice).

Sunday, 31 July 2011

67 Cremina - Asbestos Insulation Removal

I'm not sure what this stuff is on the outside of the boiler. It looks like cement, but from what I read, I'm pretty sure there is some asbestos relative buried inside. Whatever it is, I'm not taking any chances and decided to remove it. The insulation is in good condition (no flaking), so it might be better simply to leave it in place. Still, for the sake of  my family, I figure it's best to simply get it off and out of my house. Besides, it's just plain UGLY !

I brought it outside and soaked it for 30 minutes in hot water.

Meanwhile, inside the house I put on a apron, mask, glasses and rubber gloves. In the end, this turn out to be  totally unnecessary since the insulation  simply peels off if long strips like thick, wet wallpaper and sinks harmlessly to the bottom of the pail.

(IMPORTANT !) I used a wooden paint stripper to prevent scratching the soft brass, since I am planning to shine it up like new and don't want any scratches from a metal scraper or wire brush.

Here's what it looked like after about 10 minutes of underwater peeling.

Apart from the chunks that fell to the bottom, the water was surprisingly clear. Still, I got out my funnel and a coffee filter and did a "pourover" to filter the water into another bucket which I dumped.

The chucks that were left (and the filter) were then stored in an airtight plastic container, which I will bring to my city for proper disposal.

So here's what's left after removing the insulation. (On the right is a spent Howitser shell for comparison......double boiler Cremina anyone? Hee Hee).

I liked the nice patina finish on the boiler after the insulation was removed. Still, my plan is to shine it up. But that's tomorrow's job.