Cimbali squeal during brewing

[Albe]

Hello all.

First time posting here but I have gotten great advice on this forum. Here is my problem. I recently changed out the pump on a cimbali m29 selectron. The pump is working fine and pressure is stable during extraction. However, at the end of the brewing cycle there is a squeal. It is more pronounced on one group but both make the noise. To me it sounds like there is air being compressed in the system. Is it possible that air entered the group heads when I changed the pump? Is there a way to purge air from the group head if that is the problem?

Thanks for any help.

 

[CCafe]

If you trust your pressure gauge on your machine then do the following.

Tools needed:

Metric 3 Allen wrench
Metric 2 Allen wrench
6 - 8" long flat blade screw driver

Instructions:
Remove the right side panel from your M29.
Put a blank or blind basket in your portafilter like your going to do a cleaning.
Remove the drain tray.
Feel around if you don't see the drain tube behind the panel so you can locate the tube for the group you are working with.
Put a paper cup under the drain tube to capture excess water from the testing.
Now put it in the group and press any button for that group.
Wait till the pump pressure comes up to 9 bar.
A. If you hear a squeal and you're at 9 bar read Expansion Valve section.
B. If you hear a squeal and you're above 9 bar turn your pump down, repeat A.
C. If you hear a squeal and you're below 9 bar turn your pump up, repeat A

Expansion Valve
Your expansion valve has that little M2 Allen nut holding the main slotted screw in place and keeps it from backing out.
Loosen that screw to make an adjustment.
Put the blank portafilter in the group turn it on.
When the pressure hits 9 bar, adjust your pump pressure to 11.5 bar.
At this point your expansion valve should be squealing badly. There is a drain line attached to the expansion valve and connects to the black drain tub.
It should be weeping 1 droplet of water every second.
Adjust the slotted screw until it weeps 1 drop (Not a river, or a gusher, and on the reverse side not a drop that slowly dribbles down the side, we want 60 drops per minute)
Once this is done readjust the water pressure back to 9bar.
The expansion valve is now set properly and the squealing noise should go away.

Post if you have other issues.

 

[Albe]

Thanks for the reply! I will double check my machine's gauge with a portafilter mounted gauge and work from there. Hopefully that is the only issue. I'll post with results.