Mara X pressure builds continuously before venting at base

pandabear

I bought a Mara X from BB nearly 3 years back and today when I turned it on as normal, the boiler pressure built up without any control and exceeded 3 bar so much that the needle passed 3 o’clock and steam pressure was released at the bottom of the machine.

I immediately shut the machine off and drained the boiler but have left the machine off since.

I last descaled the machine a year ago and since then have exclusively used Osmio Zero water through it. I usually have milk drinks so when I shut the machine off I always purge 200ml from the boiler so it’s not sitting with overly mineralised water.

Has anyone come across this problem before and do you have any suggestions on what to try to fix it? I’ve taken it apart to do the OPV re-route but I’m not super familiar with the innards of the machines so layman’s advice to start would be appreciated!

DavecUK

pandabear It’s possible the temperature sensor has developed a fault and that might be the first thing to check/replace. especially if readings are erratic.

pandabear

Thanks for the swift reply Dave. I actually flicked between mode 0 (steam if I’m right, I’m on a V1 machine) and back to mode 1 (coffee mode ie. walk up and pull my shot) and it seems to have stabilised, oddly.

The machine pressured up past 3 bar when I reset the mode to coffee mode but then has dropped back to 1.5 bar since and stayed there with the pump going occasionally. Just ran a backflush for 20 seconds, pump at 9 bar and pressure hasn’t gone mental since (activated the boiler a few times, went up to 2 then pump activated momentarily and now idling around 1.5).

Is there an easy way to test the temperature sensor since I have the top off the machine off at the moment, or am I better off leaving everything as is for now?

DavecUK

pandabear Is there an easy way to test the temperature sensor since I have the top off the machine off at the moment, or am I better off leaving everything as is for now?

No, and wobble the wires around too much is a sure way of breaking it.

pandabear

Side question - is idling between 1.5 - 2 bar actually normal? What I keep seeing now I’m Googling is that the pressure should rest between 0.5 and 0.75 typically?

Doram

pandabear is idling between 1.5 - 2 bar actually normal?

You can see how my machine is idling in these two time-lapse videos below. This is coffee priority with temp setting 0 (the lowest). I think idling between 1.5 and 2 bar is too high, at least compared to my machine (same version and about the same age as yours).

This is starting the machine from cold:

And this is idling after a shot:

DavecUK

Doram Looks fine to me?

pandabear

DavecUK

Doram

Sorry for the late reply, I had a break abroad with the family. Yeah let me know if it falls though and I will consider!

I fitted the new probe at the top of the machine today and it has definitely made some difference, the machine seems to temp cycle now without over-pressurising (only tested the once from startup, though). I’ve attached a 1.5 hour timelapse from when it peaked steam pressure and then began dropping steam pressure before cycling to maintain temp. I was expecting it to sit between 0.75 and 1.25 like yours @Doram, maybe a bit higher because I’ve got mine set to temp setting 1, not like yours was at with 0. It behaves similarly but then around the 45 min mark ramps up and cycles between 1.5 and 1.75 perpetually from that point on. Does it look normal (for temp setting 1)? I’ll change to 0 and see what happens in the meantime.

Edit: it has now settled at setting 0 and behaves exactly the same, between 1.5 and 1.75.

Doram

DavecUK Doram Looks fine to me?

Yes, this is my machine and it’s fine. I uploaded the videos for @pandabear, because his machine is idling between 1.5 to 2 bar and he asked if this was normal, so this was just for his reference.

pandabear

Confirming my suspicions that the temp has been off a bit for a while and this issue is probably a culmination of that.

The issue happened again earlier after I let the machine idle for over an hour. Slowly built up and then tripped over.

Wondering if I should look at the steam temperature probe before I check anything else. Seen another person has some loose wiring at the bottom of the boiler too so might up taking off the casing and checking all wires/connections properly.

pandabear

Edit: should have said check the temp probe first as I’ve also been advise to check/swap the pressure stat (is that the actual dial on the front?)

DavecUK

pandabear MaraX doesn’t have a pressurestat. As I said before, change the temp probe. It could be the one in the HX circuit, but more likely the one on the top of the boiler.

https://coffeeequipmentreviews.wordpress.com/2020/03/10/lelit-marax-review-in-progress/#temperature

It’s worth mentioning the temp probe on the top of the boiler is a combined temperature and Level probe!

There should be an extra boiler plug on the top that’s not used, if so undo it. Then buy a separate level and temperature probe, The combined one can be more expensive. The wiring is self explanatory.

pandabear

So I’ve given the level probe a good clean and reassembled but the temp probe is ridiculously stuck when I try and remove it (to check and clean for good measure). It’s so tight and understand they use a thread locking glue on it.

Any ideas or tips to get this moving please?

DavecUK

Top off photo please…

pandabear

https://ibb.co/wsbjFgt

https://ibb.co/KwjV44Y

https://ibb.co/1s4Xzf1

DavecUK

pandabear OK, I can now see yours doesn’t have a combined probe. Cleaning of the temp probe won’t fix your problem and removal to clean is not advised as it usually breaks them (the little wires inside fracture due to all the bending at the top).

As I said before replace the probe…yes you may have to brace the boiler and use a socket to get it off…or even a small electric impact wrench. With the correct size socket attached…then it will come of easy without damaging anything.

https://tinyurl.com/29u8vxqw

pandabear

Thanks Dave. I’ll see if the level probe clean helped and then move to the temp probe then. Lelit mentioned to me that one exists at the bottom as well as the one at the top. Do you have experience with if both need replacing?

I’ve also read that some of them from 2021 batches were faulty after switching suppliers and Lelit resorted to their original supplier later that year. Mine appears an early 2021 model. Is there any recourse or if the cost burden likely on me? Sensors aren’t exactly a few quid!

DavecUK

pandabear Change the top one first, be careful as if that’s not the problem, you can try transferring the top one to the bottom.

pandabear

Thanks Dave, I’ll order the part(s) in the coming days. I noticed you mentioned your Lelit Elizabeth potentially up for sale soon, is that still on the cards? I’m interested in trying one out.

DavecUK

pandabear Thanks Dave, I’ll order the part(s) in the coming days. I noticed you mentioned your Lelit Elizabeth potentially up for sale soon, is that still on the cards? I’m interested in trying one out.

That’s already sold to a forum member some weeks ago. I have had a really bad back this last week, as I should have been preparing/testing a Lelit Bianca Version 1, to check it was fine to sell and is working perfectly. Someone sent me an e-mail saying they wanted it. It’s essentially been used 4 weeks only then stored in my house for years. I actually purchased it with my own money after reviewing it, and am looking to get some of it back.

If that falls through, then perhaps that will be of more interest….@ £850, but it will be collect only.

MediumRoastSteam

DavecUK I have had a really bad back this last week,

I blame you having to lift the Evo up onto the countertop :-) - Get well soon.