I had a problem like that with my Brewtus 2. It was fixed by lowering my steam boiler pressure to about 1.3 bar and hasn't happened again.

The problem only happened when the machine was hot and it started in the summer. I suspect my vibe pump has a klixon (an overheat protective device) that was kicking in when the environment inside of my machine got too hot.

My on/off power switch did eventually kick the bucket due to heat after about 4 years of light use. The replacement was cheap enough (less than 3 dollars) but these type of switches don't seem to be made for handling heat. The new Brewtus models now have metal toggle switches.

I wonder if some of these machines would benefit by having a fan placed inside them like a computer given the amount of non commercial parts placed in them. With my machine in mind I can recall the vibe pump of course, non - 220 volt wiring, plastic parts and componants, non commercial pressurestat, lots of teflon/silicon tubing (I would like solid copper.) These little downgrades keep the price from approaching that of a full fledged commercial machine and for the most part works well enough in a non-commercial setup most of the time.

I also wonder how much variance does one klixon have from another. Whatever the case I would suspect the vibe pump is getting more heat than it can handle.

The thermal fuse is seldom the problem. Removing it never made any difference. I don't recall exactly, but when I checked the rating, it was well above the values encountered in an espresso machine. You'd have to run the pump dry for several minutes to exceed the trip value.

A fan could change the dynamics of the thermosyphon. Maybe +, maybe -
Noisy and prone to failure in a high heat environment.

I suspect my vibe pump has a klixon (an overheat protective device) that was kicking in when the environment inside of my machine got too hot.

Think of the brand name "Klixon" like Kleenex, Xerox, Channelocks, etc., etc. The word "Klixon" is actually embossed on all(?) Ulka pumps just above the slot where it would fit. The thermal fuse/switch I am accustomed to seeing carries the brand name "MIO". It is cylindrical, 8 mm in diameter and ~ 3 mm tall.

Another brand name for a thermal fuse/switch is UCHIYA. That model number is UP72 and has a 100C rating. The data sheet is here: http://www.uchiya.ie/UP7.html .

I have previously referred to this Klixon as a thermal diode and was told that is incorrect via a PM from a forum member. I agree with him although my minor research effort on these gizmos did, from what I remember, use the term thermal diode (that reference doc is nowhere to be found today). Anyway, they are self resetting thermal switches and are present on lots of Ulka applications as well as rotary pump motor windings.

And here is a pic of the mechanically x-rayed Ulka coil (deceased).



Items 1 & 2 are the male terminals on the pump, item 3 is the rectifying diode, item 4 is the diode connection to the coil winding.

cafeIKE wrote:I've had several Ulka pumps exhibit the same behavior after a couple of years. IMO, it's not a power issue. Or the thermistor as they're almost bulletproof. It's an age / buildup[?] / thermal issue. All through the winter, the pump is fine. Once the morning temperature gets above about 72°F or the machine is left on all day Saturday, raising the reservoir temperature, the pump starts to fail. Fill the reservoir with cool water or remove the side covers and the problem stops.

Tired of forking out $50 a pop for a new pump, and having several duds about, I disassembled the oldest.
See http://www.madeinthegarage.com/articles...g=fr&pg=36 and http://ulkapumprepair.blogspot.com/ for instructions and images

Soak all parts save the motor overnight in a weak, about ½ teaspoon to a cup, citric acid solution. Rinse and Reassemble. Rebuilt has worked flawlessly all summer.

NOTE : Recommend dis/re assembly on a baking sheet lined with a tea or paper towel.
EricS knows why

I gave this a go over the weekend. Sadly it did not fix my issues. Pretty enlightening project though. Once I order a new pump I think I can have it changed in under 30 min. Still wondering if I should switch to a fluid-o-tech replacement pump or get the whole OEM pump/OPV assembly from WLL.

I was notified of this same issue while working on a friend's machine just last week. Almost all Ulka pumps in these machines are equipped with a thermal fuse (discussed in previous posts). I bypassed his fuse and the "problem" APPEARS to have gone away. For sure, time will tell. Obviously, by-passing the fuse is a one minute job once the machine is opened and the potential problems one could encounter when doing this are close to zilch.

The thermal fuses are available separately. iirc, from Chris Coffee, but I don't remember where I saw them.

OK, an update on the status of my machine... Per Chris' as well as local espresso repair shop's recommendation, I replaced the pump with a new Ulka pump from Chris and all of the issues went away.

It works as good as new now. Thank you every one!