Sunday, June 17, 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.








1 comment:

  1. Hi,
    I’ll be learning about some of the features as I go along. I hope that it eventually proves easier for you the reader to follow the postings and comments.

    Thanks!
    Shaft Seals

    ReplyDelete