Puff of air released when the lever is raised

Matthew Hoffman

I've recently noticed that at the point when I release the lever after preinfusion, there is an audible sound ("psst") of air being evacuated. There doesn't seem to be any associated problem with the espresso, but it has made me curious. Perhaps it is a sign that the bore needs regreasing?

Matt

Reiss Gunson

hi matt

thanks for posting

my first thought would be, at what angle is the lever grabbing? e.g. 45 degrees?

have you tried lengthening the duration of the pre-infusion phase, for example, by adding three more seconds?

kind regards

reiss.

Matthew Hoffman

I tried that, raising the infusion time from 7 to 10 seconds. But I still heard the puff of air being released. What are you thinking causes the phenomenon?

Matt

Reiss Gunson

hi matt

as you probably know, when the piston is raised and the water is forced into the brew chamber through the four ports it does not fill completely to the bottom of the piston with water; there is an air space between the bottom of the piston and the top of the water

it sounds as though you are hearing some (all) of this air move past one or more seals as the piston comes down, hence my question about the angle at which you observe the lever grabbing/being arrested - if it is too high then yes, it is worth changing the seals, or if you are lucky simply re-greasing the bore (although i suggest this is false economy if you can feel that the heat has begun to rob the seals of their elasticity to any extent)

kind regards

reiss.

Matthew Hoffman

I think the lever has been grabbing a little higher than 45 degrees. I've changed the seals once since I've had the machine, but I don't recall how long ago. Anyway, I'll pull the spring/piston assembly out when I get a chance and have a look. Thanks for your assistance,

Matt

Reiss Gunson

i am getting 18 months plus out of my seals with Loxeal no.4 grease (the machine is on from 0500 to 2200 each day)

if the seals have begun to harden (from heat) i suggest replacing them as it is unlikely that they will seal as effectively once you have had the group out

Victor Sherman

Matthew
My bet is your portafilter gasket is up for replacement

Matthew Hoffman

Yesterday I took the piston assembly out of the group. The seals were still soft but the bore was completely dry. I think this is because that I didn't use very much Loxeal when I last changed the seals. Having seen your helpful video, I used much more Loxeal this time to re-grease the bore.

The puff of air has now disappeared and the lever is catching around 45 degrees.

Thanks for your help,

Matt

Reiss Gunson

great!

Matthew Hoffman

UPDATE: After a couple of days, the puff of air returned, so yesterday I pulled the piston assembly and looked again at the seals. I observed that although they were soft, they were nearly flat. The flares had worn off, probably because they had been sliding in a dry bore. This time I replaced the seals. I am happy to report that not only is the puff of air gone but the lever catches noticeably lower than before and with a more solid feel. I should have followed Reiss's original suggestion to replace the seals the first time. He knows his machines.

Matt

Reiss Gunson

thank you for the update matthew. kind regards. reiss.