Machine is a 5 year old Lelit PL41. id say well maintained ( back flushed and descaled regularly).

I typically heat up my machine for 30-45 minutes for my first shot of the morning, and everything works fine. I leave the machine on and go to make my second shot of the day a couple of hours later. Lately when I do this, the pump just gives a low hum noise, and little to no water comes out. maybe a dribble of water if I wait long enough.

After repeated attempts it usually starts working again. And by the next morning all is fine again.

Now I've read that heated water will cause issues with ulka pumps, which would explain why the problem is only present after a long idle. However it never behaved this way before so why now?

Any ideas? I'm up for disassembling the pump if I know it will fix the issue.

Also, is there any way to rule out something else as the problem (OPV?)

baldheadracing wrote:Somewhere here/Internet there are disassembly instructions.

From Repairing a ULKA vibratory pump:

HB wrote:Someone contacted me offline asking if it's possible to repair an espresso machine's vibe pump. It took awhile to relocate this very helpful how-to due to its obscure title: I ended up with a free Starbuck. I'll add this to the Resources page for future reference.

Below is another great schematic from Eric:


From Pump? OPV? Check Valves? Wit's end!

Thanks for the info. I guess my only hesitation to pulling apart my pump is - it works fine for the first hour or so of the machine being on. I only get this problem after the machine sits for a couple of hours ( which is why I think it's heat related ).

Does this sound like a problem that might be fixed by taking apart and cleaning the pump?

Maybe open the top and run the pump and make a note of how much it vibrates. Leave top off and wait an hour and see if it still does it. If does it, then pump still vibrating the same? Then touch the pump output (white plastic part) and see if it feels hot. Does it feel hot or regular? Look at the feed tube and is still water in there? Make sure you don't touch anything else so don't shock yourself, it really hurts. Maybe can figure something from all that. Or not.

Update...

I disassembled the pump, and surprisingly is was very clean. No scale or buildup of any kind that I could see. I didn't even bother soaking it because it was clean.

Could the solenoid be bad?

The pumps do wear out over time, and 5 years is a pretty good run. Time for a new one. They are fairly easy to replace.

These pumps have a lifespan, and you've hit it. My first one lasted 7 years, my second lasted a month, and my third one is going fine (I think the 2d might have been because of a solenoid issue I discovered later).

I rebuilt it, in part for the experience, following what the guy did above. Interesting, but not worth it - pump died again in a month, and I just ordered one from chris coffee. They are reasonable enough, and the repair process of disassembling a vivaldi annoying enough, that I didn't want to be in there rebuilding every month.

(note, issue was with different solenoid)