'New' Cafelat (blue) piston seals v 'old' Cafelat (red) seals for CMA group

#1: Post by **Paolo** » November 29th, 2020, 11:30 pm

Has anyone with a CMA-type lever group machine replaced Cafelat (red) seals with the new blue seals that are now recommended by Cafelat?

Just wondering if you noticed any difference in operation/performance with the new blue seals.

#2: Post by **allon** » November 30th, 2020, 7:40 am

I just replaced the original BUNA (?) rubber seals with the blue cafelat seals.

It's super tight and I'm having water flow issues - I think these are incorrect for this machine. Espressoparts had only the blue seals and had them as appropriate for the CMA.

I think I'm gonna have to take them off

#3: Post by **Paul_Pratt** » November 30th, 2020, 7:00 pm

Paolo wrote:Has anyone with a CMA-type lever group machine replaced Cafelat (red) seals with the new blue seals that are now recommended by Cafelat?

Just wondering if you noticed any difference in operation/performance with the new blue seals.

I added 0.5mm to the height of the middle section and increased the OD by a similar amount. There is no performance benefit, but an attempt to address the small number of people who cannot use normal seals.

allon wrote:I just replaced the original BUNA (?) rubber seals with the blue cafelat seals.

It's super tight and I'm having water flow issues - I think these are incorrect for this machine. Espressoparts had only the blue seals and had them as appropriate for the CMA.

I think I'm gonna have to take them off

That makes absolutely no sense to me, the blue or red gasket would not affect that. Make sure the piston is on all the way, make sure the sleeve is being pushed down into the group. Is it a new o-ring on the sleeves? A fatter o-ring may prevent the sleeve from being pushed down all the way.

#4: Post by **allon** » November 30th, 2020, 7:41 pm

Hm, I wonder if I dislodged the sleeve pulling up on the piston. I did make sure the piston is screwed in all the way.
These seals are super tight, it was hard to pull the piston out of the group.

Isn't the sleeve pushed down by the group cover?
I didn't change the sleeve seals.

November 30th, 2020, 8:04 pm

Yes, it's baffling

Hm, I may have found the issue. Working on it...

#6: Post by **allon** » November 30th, 2020, 8:37 pm

Oksy, so apparently when I changed the spring out for a stainless spring one a few years ago, I ended up with a piece of zip tie left behind, and it was wedged into the spring; must've shifted position when I changed out the seals.

Seems to be somewhat better now, but still not 100%. There's a piece lodged in there that I just can't get out.

I have a friend who may have a spring compression tool, I'll have to see if we can disassemble/reassemble the lever assembly. Otherwise I may just continue with it as is. So not related to the seals.

#7: Post by **Oskuk** » December 1st, 2020, 5:42 am

I have flow-issue too on my CMA Astoria, but I do not think there is anything to do with the seals. Changed one red for blue, but they seemed quite a like.

as I wondered why there is bad flow I measured the place where the holes are. Did not get any viser barista with that.

#8: Post by **Paul_Pratt** » December 29th, 2020, 9:22 pm

OK so Allon sent me a message about his group again, saying the blue seals are a problem for him with water flow. I stand by what I said earlier that on a standard group the seals and the water flow are not related and it must be due to the sleeve hole height and the piston position. I pulled out 2 groups today.

First up is a comparison of the older CMA style group (left)and the more modern group (right). I placed the sleeve up against the prongs of the upper group to show the position.

At rest the sleeve holes should line up near the teflon spacer, inbetween the middle and upper seal. Here is better photo of the right group with the sleeve.

Next images will show how that when the lever is pulled, not just the seals but the entire piston should clear the holes by a few mm. The springs are compressed

CMA group

Modern lever group

Lastly to confirm that the piston clears the holes, a shot up inside the group with the lever pulled down - water hole is marked with the arrow

I have measured 6 groups now, the blue seals were actually tested in both modern groups and my own vintage Astoria Fiore. I would say parts have been changed or the sleeve holes are higher than normal.

#9: Post by **EddyQ** » December 29th, 2020, 11:49 pm

I've had the blue seals on my KvdW Idro for about 2 weeks now. They seem to work great. For reference, my machine has the modern group.

The only issue I had was due to an oring, which Kees has installed with top seal. I first tried installing the oring with the blue seal and it was too tight. I removed the oring and things seem to be working fine. Time will tell.

December 30th, 2020, 5:42 am

I just checked your posts. yes no need for the o-ring. I can sort of guess why it was added to take up slack since the black seals are smaller than the groove.