Lelit Mara X - Steaming hot water out brew priority mode

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dandua98

#1: Post by dandua98 »

I started my machine's pump with the portafilter off to heat up the portafilter (I usually just leave it on while the machine's warming up). Surprisingly the water came out steaming for a bit, which I thought wasn't supposed to happen with Mara X on brew priority mode. I did leave the machine on for a bit before pulling the shot and I know on E61 group heads a cooling flush is needed but from what I've read that's not the case for this machine. This also explains the shot variation I've been seeing recently but that is a bit disappointing. Is this normal? I've also been seeing high resting steam pressure recently (but in the range mentioned on the extended manual)

woodbar

#2: Post by woodbar »

Had exactly the same problem a few weeks ago.

Supplier diagnosed a faulty temperature sensor - the top (steam) one and sent me a replacement.

I fitted this and it made no difference - so I replaced the bottom sensor (brew/HX) with the one I had just removed from the top location and this cured the problem.

From my experience and reading other posts and forums it generally seems that a fault on the top sensor tends to create very high steam pressures (gauge off the scale) and possibly the steam safety valve letting by. Whereas a fault in the lower HX sensor tends to create very high brew temperatures (possibly steam from the group) and the steam pressure sits around 1.5 bar all the time as it is not allowing the cooldown for "coffee priority" - basically working as a normal HX machine!

dandua98 (original poster)

#3: Post by dandua98 (original poster) »

Hmm, interestingly my problem doesn't seem to happen that often. Maybe I should get a grouphead thermometer to see if there's a lot of variability to confirm if it's a faulty sensor. But yeah not a huge fan of having to do cooling flushes on a machine with temperature stability as a boasting point

DaveC

#4: Post by DaveC »

dandua98 wrote:I started my machine's pump with the portafilter off to heat up the portafilter (I usually just leave it on while the machine's warming up). Surprisingly the water came out steaming for a bit, which I thought wasn't supposed to happen with Mara X on brew priority mode. I did leave the machine on for a bit before pulling the shot and I know on E61 group heads a cooling flush is needed but from what I've read that's not the case for this machine. This also explains the shot variation I've been seeing recently but that is a bit disappointing. Is this normal? I've also been seeing high resting steam pressure recently (but in the range mentioned on the extended manual)
It would depend on the exact timings and events prior to you drawing water. e.g. how long was it on for before you pulled water out of the group, did you pull any water from the group prior to this.

dandua98 (original poster)

#5: Post by dandua98 (original poster) »

I think for more than an hour and a half since I first turned on the pump, and didn't pull any water from either the grouphead or the bypass before this

woodbar

#6: Post by woodbar »

Presumably your machine is under guarantee - have a word with the supplier.

The symptoms you describe are almost exactly the same as the problem I had and were cured by replacing the lower HX temperature sensor - obviously with the machine in coffee priority mode using the PID it should not produce steam from the brew group!

Note my supplier stated it would be the top sensor ("always is, we have never changed the lower one") so my machine proved to be the exception to the rule!