Introduction: Rebuilding an ULKA Vibratory Pump (Espresso Machine Pump)

Picture of Rebuilding an ULKA Vibratory Pump (Espresso Machine Pump)

The most popular pumps for mid-range espresso machine are undoubtably those manufactured by the Italian ULKA company. The pump I rebuilt here is the ULKA H58, which is discontinued. However, many machines still contain this pump, it can be had as a replacement part from some suppliers (Cerini Coffee), and it's one of the simplest vibratory pumps to work with. Internally, it's much the same as the ULKA E8 series, though it's rated at 15 bar.

Rebuilds of some other pumps:
ULKA EX5
ULKA EP4 (French, but useful images and animations)

Step 1: Remove Pump Body From Solenoid.

Picture of Remove Pump Body From Solenoid.

The pump body is simply screwed into the solenoid at the head nut. It should come out easily enough with a wrench on the head nut and the solenoid held in your hand.

Step 2: Remove the Pump Head.

Picture of Remove the Pump Head.

The pump head and body are held together by nothing but friction. Don't worry: it's supposed to be that way. Twist and pull at it until it comes free of the pump body. You should be able to pluck the shuttle from the innards of the pump now as well.

Step 3: Disassemble the Inlet.

Picture of Disassemble the Inlet.

It really is an ingenious design. Once the pump body is removed from the solenoid, nothing really needs unscrewing or unbolting. The simplicity of design is one of the reasons why these pumps rarely need to be replaced: just take them apart, clean up the parts, and slap them together again.

Anyway, pullout the inlet fitting. You should be left with the pump body, the shuttle return spring wedged inside it. Use a blunt implement like a chopstick or bamboo skewer (to avoid scratching the inside of the pump body) to carefully push the spring out the inlet end of the body.

Step 4: Disassemble the Pump Head.

Picture of Disassemble the Pump Head.

Now it's time to take apart the pump head. This is where all the action is, really: it converts the reciprocating motion of the shuttle to a one-way pulsatile flow. (In electronics terms, it's contains the diode: it's a half-wave rectifier. Of course, they used to refer to diodes as "valves" for a reason...)

First, push the head nut along the outlet to reveal the pump head itself. The shuttle bumper will probably fall right off.

Step 5: Continue Disassembling the Pump Head.

Picture of Continue Disassembling the Pump Head.

The important part of the pump is also the most delicate, so be careful! The check valve is a tiny little snip of a thing, and it'll make you wonder how in the blue blazes it manages 15 bar pressures.

Carefully pick out the check valve gasket from the pump head and set it aside. Then, even more carefully shake out/pick out with a toothpick the check valve itself: it's a tiny rubber pellet on the end of a spring that looks all-too-easy to irreparably damage.

Step 6: Line Up the Parts for a Spiffy "exploded View" Photo.

Picture of Line Up the Parts for a Spiffy "exploded View" Photo.

You wouldn't take things apart and be left with no evidence of your prowess, now, would you?

Well, you don't necessarily take the picture yet. First you fix whatever turned out to be the problem, and your motivation for taking the thing apart in the first place. In most cases, it's simply scale and corrosion, which can be solved with a combination of 50:50 vinegar:water, cotton swabs, and steel wool. Just take care to fully rinse all parts before reassembly.

Oh, and take the picture, too!

Step 7: Reassemble and Test.

Picture of Reassemble and Test.

Hopefully your espresso machine is constructed such that a non-installed test setup like this is possible. It'd be highly annoying to completely install the thing and find out it's not yet working. Just be sure not to run it for too long at a stretch on a dry boiler: you did drain the boiler before you started monkeying around with this, didn't you?

Step 8: Optionally Adjust Output Pressure.

Picture of Optionally Adjust Output Pressure.

One thing you might want to do before you get the machine entirely together is adjust the pump output pressure. Somewhere along the water line between pump and boiler (and usually as shown quite near the pump) is an overpressure valve, which is essentially a check valve with an adjustable high cracking pressure. In an ideal case, this will crack somewhere around 10 bar, permitting brew pressures in the 8.5-9.5 bar range. However, in most pumps this is set too high.

First thing to do is mark the current setting with a Sharpie on both adjustment nut and casing. Then remove the valve core by loosening the adjustment nut fully, and swab out the inside with vinegar, flushing it well with water: a sticky overpressure valve can cause excessive and inconsistent brew pressures. Depending on the machine, the factory setting may be fine (especially if you've been getting good shots out of it). However, if the machine shipped with a pressurized portafilter, it's almost certainly several bar too high, and needs loosening. With most two- and three-turn OPVs, adjusting in 1/2-turn increments seems to be a good starting point. However, with no means to measure pressure, you'll have to assemble the machine each time and pull a test shot with known-good coffee.

See Home-Barista.com for more details.

Comments

BenjaminG35 (author)2017-07-02

My rebuilt 1980s Brasilia machine has this vey H68 pump and it is still going strong! Although it is louder than those plastic casing Ulka in my most recent machine. I was wondering if there was any change i could reduce its operating noise by a pump rebuild? Also, the pump is directly connected to copper tubing instead of teflon, so this migh actually be what contributes to the noise? any ideas? thanks!

kredfish00 (author)2015-03-06

I have an H 64 which seems VERY much like your H 58. I have 2 questions:
1.) The pump seems to have a good bit of rust and corrosion from I assume water sitting in the valve. This was from a commercial machine used at the 1984 World's Fair and now only sees occasional use. Is there an alternative ULKA pump I should replace it with that might stand up better to the occasional use scenario?
2.) I cannot seem to get the inlet side out. Is there a trick or a tip you can offer?
Great article!

dave713 (author)kredfish002015-04-19

30 years bit long enough> Most ulkas last 5 to 10 years. cost is $40 to 60

Major Woody (author)2011-01-09

Thank you so much for this guide. My Saeco Rio Vapore has the Cosmec pump, rather than the Ulka. But internally they are quite similar. You need a set of snap-ring pliers to get the Cosmec apart, but after that it is pretty self explanatory getting them apart, cleaning them etc. I ran a tank of descaler through mine and that didn't fix it. Taking it apart and cleaning/shining up all the internals did fix it and I have no reason to believe the fix won't last.

Your article inspired me to do it.

Definitely a good idea to photograph things as they come apart. Parts look similar and reassembly is not exactly intuitive but it isn't rocket science either.

Thanks again!

dave713 (author)Major Woody2015-03-10

YOu are rebuilding old junk. remember that the water that comes out of that ancient boiler is GOING INTO YOUR BODY!

DUH!

Major Woody (author)dave7132015-03-10

Dave, please expand upon what it is in this brass pump and/or brass boiler which I am ingesting by descaling the unit and/or by cleaning my pump out and reassembling it. I am using a descaler marketed specifically for periodic maintenance of espresso machines.

Just because something is not designed to be repaired, doesn't mean that it shouldn't be, when appropriate. My time is worth whatever I think it's worth, so if I want to spend an hour cleaning my machine's pump, that's my prerogative and it doesn't make me an idiot. Indeed, by repairing this machine, I now have at least $160 in my pocket ($50 pump, $10 gas, $90 labor) that I can use to take my family out to dinner--money I would not have if I had simply unplugged the machine and brought it to an equipment service place to have the problem diagnosed and the pump replaced.

You seem to have an Internet Warrior thing going here in this thread, without offering any rationale behind your posts. If you have advice to offer based on your experience servicing espresso equipment, your advice will be much more credible (and appreciated) if you would please turn the caps lock off, save the condescending attitude and explain the reasoning behind your recommendations. Thanks!

dave713 (author)Major Woody2015-04-19

There is LEAD in older boilers, as much as 1.5 %. VERY bad for you.

kredfish00 (author)2015-03-06

One more question.....if the piston shows pitting on the bottom, should it be replaced? and if so, is there ANYWHERE to find replacements parts for these old pumps?

dave713 (author)kredfish002015-03-10

NO! THEY ARE 30+ YEARS OLD!

kredfish00 (author)dave7132015-03-11

Yes Dave...I hear you! Which would you recommend as a replacement the EAP5 or the EAX5 or some other model? It is amazing how easy the old ones are to clean up and get going though.....

dave713 (author)kredfish002015-04-19

ANY of the current Ulka 41 or 52 watt pumps will be fine.

bruce honnigford (author)2015-03-25

This article help me make a decision. Years ago I bought a used Gaggia Classic on Ebay and it was in bad shape. However, being very handy, I overhauled it, got it working again and enjoyed maybe another year out of it before it crashed again. I put it away, forgot about it and became a regular at my local coffee shop. Since then I moved away and have been craving cappuccino again. So I pulled out the old Gaggia and started tinkering with the pump. It looked pretty much like the one you have pictured here. Sure, I could have gotten it going again - for a while- but I decided to buy a new machine instead. Why did I go through so much trouble fixing up a junk machine all those years ago? Because I loved cappuccino, I had an engineering degree and I was kinda broke. Saving $40 bucks mattered more then and it felt great making something work with my spare time.

dave713 (author)bruce honnigford2015-04-19

very good sir. Not to mention all that rotting aluminum in the boiler! NOT the best thing to put in one's body, IMHO.

dave713 (author)2015-03-10


Dave, please expand upon what it is in this brass pump and/or brass boiler which I am ingesting by descaling the unit and/or by cleaning my pump out and reassembling it.

You are connecting this ancient pump to a machine that is ~ 30 years old. DO you know what is in the boiler? I do not.

I am using a descaler marketed specifically for periodic maintenance of espresso machines.Just because something is not designed to be repaired, doesn't mean that it shouldn't be, when appropriate. My time is worth whatever I think it's worth, so if I want to spend an hour cleaning my machine's pump, that's my prerogative and it doesn't make me an idiot. Indeed, by repairing this machine, I now have at least $160 in my pocket ($50 pump, $10 gas, $90 labor)

does someone PAY you $90 and hour? no. then your logic is flawed!!

that I can use to take my family out to dinner--money I would not have if I had simply unplugged the machine and brought it to an equipment service place to have the problem diagnosed and the pump replaced.You seem to have an Internet Warrior thing going here in this thread, without offering any rationale behind your posts.

rationale??
One does not WASTE time on old junk.

If you have advice to offer based on your experience servicing espresso equipment, your advice will be much more credible (and appreciated) if you would please turn the caps lock off, save the condescending attitude and explain the reasoning behind your recommendations. Thanks!

OK. these pumps are not meant to be rebuilt. BUT, if you have nothing but time you are welcome to it.

UNlike amateurs, we have to warranty the work we do, and fixing a disposible pump is NOT the way to a happy customer. Especially when I pay $27 for new brass ULKAS

Zak (author)2007-07-12

I have repaired two espresso machines by just descaling the pump. On the first (I still use it 10 years after) I used a syringe to force bathroom descaler through the bump. It came out as foam again and the pump was working instantly. The next one was a friend's. I figured out that by putting descaling fluid in the tank and repeatedly heating up and cooling down the machine, I would pull this liquid through the pump. That worked indeed, but the descaler I used was perfumed and also designed to leave a glossy coat on the bathroom. That took quite some time to get rid of. Thomas

dave713 (author)Zak2015-03-10

ARE YOU SERIOUS?

xsmurf (author)Zak2007-07-15

We use white vinegar. Works like a charm, cheap... and none toxic. Just leave the machine running for the length of one or two servings to get the taste out.

dave713 (author)xsmurf2015-03-10

yeah get the stink out.

NOT what you want to use.

sehrgut (author)Zak2007-07-12

Gah! I can't even imagine the flavour/odour of bathroom descalers in coffee! To say nothing of the fact that they're incredibly bad for any plastic water lines and rubber gaskets in the machine (and pump). In a pinch, vinegar will do as a circulating descaler, but something along the lines of citric acid (I've even heard of people using formic acid, but I wouldn't), or one of the "gentle" sodium-carbonate-based coffee machine descalers, are what you want.

You can pick up citric acid for a few dollars a pound at soapmaking and homebrew shops, which is a lifetime supply for an individual, and even a several-year's supply for a cafe.

About This Instructable

64,507views

14favorites

License:

More by sehrgut:Quick, Sturdy Wooden Marudai (for Japanese Kumihimo Cord Braiding)"Fluxx: the Board Game" Pegboard HackHacking the Cuisinart SupremeGrind for Espresso
Add instructable to: