Dear Coffeetimer's I rebuilt my Isomac Millenium after something went catastrophically wrong, something that caused the pressure in the machine to run up, the boiler safety valve then failed to operate and water filled the pressure gauge. I was next to the machine and quickly turned it off. Since then I have replaced the Boiler Safety Valve, the Pressure Stat and the Gicar Controller. I have also rebuilt the Group Head, replacing all the seals and have carefully reassembled it. Now I have a somewhat unusal problem that I am struggling to understand but could be linked to the problem that caused the original meltdown. The machine turns on and quickly comes up to pressure that i have set at 1.25bar. I can hear the Pressure stat working and the green light on the front of the macchine comes on and off as would be expected. The problem is that the boiler valve in the group head becomes jambed in place by the pressure of the water behind it. The lever can only be pulled up once I have relieved the pressure by opening up the mushroom or allowing the machine to cool. When the pressure has been relieved the lever moves freely upwards and down. I have opened up the lever assembly and tried to push up the boiler valve to no avail. Once pressure drops sufficiently I can push it up with a screwdriver and water forces it way out. I have cleaned out the old OPV and ordered a new one and will look to set at 9bar. Could this be the issue? One thing that might be relevant……….I have noticed since the problem and subsequent rebuild is that when I get the machine operating and after pulling a shot there is not a release of pressured water out of the exhaust value, likewise after using a blind basket used. Something that surely should be happening? FYI I have checked and carefully reassemebled the E61. Any thought or input would be much appreciated!

> @"chriswhite"#p50214 I have noticed since the problem and subsequent rebuild is that when I get the machine operating and after pulling a shot there is not a release of pressured water out of the exhaust value, likewise after using a blind basket used. Something that surely should be happening? FYI I have checked and carefully reassemebled the E61 Is the exhaust valve not venting out at all? If not, then what happens when you remove the PF from the group? If there’s no pressure, then it must be getting vented somewhere else… I would definitely take the group apart and meticulously rebuild making sure all the seals are good and all the valves and pins are seated correctly and are the correct size.

Are the valve stems the same length as the originals ?

I would also take a photo of the group valve internals and paste it here.

I have attached photos of the valves and their position in the E61 group head as currently disassembled. https://www.dropbox.com/scl/fi/4ikzxc9wxuk27rnkfejjp/IMG_8249.jpg?rlkey=npsbeuwjqy9brr9oa3syexo3t&dl=0 ![](https://www.dropbox.com/scl/fi/4ikzxc9wxuk27rnkfejjp/IMG_8249.jpg?rlkey=npsbeuwjqy9brr9oa3syexo3t&dl=0 "Assembly ") I have not changed the valve stems, I understand from a E61 exploded diagram that the Boiler valve is 12mm, the Middle valve is 13mm and the bottom exhaust valve is 14mm. The valves inlcuding exhaust valve operate perfectly by turning the lever when the machine is not operating. https://www.dropbox.com/scl/fi/4na4nyid46erwu1slbk7u/IMG_8251.jpg?rlkey=ymb24x2io6dtsmg0g4q4svsz3&dl=0 ![](https://www.dropbox.com/scl/fi/4na4nyid46erwu1slbk7u/IMG_8251.jpg?rlkey=ymb24x2io6dtsmg0g4q4svsz3&dl=0 "Valves") https://www.dropbox.com/scl/fi/8h4mfmvfcxdvqlf113pqd/IMG_8252.jpg?rlkey=l0ei2nsmhtpawinxblkzzf6aj&dl=0![](https://www.dropbox.com/scl/fi/8h4mfmvfcxdvqlf113pqd/IMG_8252.jpg?rlkey=l0ei2nsmhtpawinxblkzzf6aj&dl=0 "Valves side by side") Two issues - that might or might not be related 1\. I am not seeing a pressure dump after using a blind PF or after a shot is pulled. 2\. The Boiler valve is being locked into place by pressure from the boiler side. A new OPV is arriving and I plan to adjust it to 9bar using a blindPF pressure gauge.

Isomac Millenium E61 Group exploded diagram ![](https://www.dropbox.com/scl/fi/3utkb9u3mnkn0xuhf0oam/IMG_8253.HEIC?rlkey=5mkrnr1yp41ishbvfz5g95spb&dl=0 "Isomac Millenium E61")

@"chriswhite"#p50285 ![](https://www.dropbox.com/scl/fi/ucbrgl203ybvfwnblxg9i/IMG_8253.jpg?rlkey=zgknk1nerqcidywg5mei0ea9w&dl=0 "Exploded E61 Isomac")

https://www.dropbox.com/scl/fi/ucbrgl203ybvfwnblxg9i/IMG_8253.jpg?rlkey=zgknk1nerqcidywg5mei0ea9w&dl=0

I wondered if the cam follower pins on the valves were worn, causing it to lock slightly under pressure, but they seem OK. The only thing is the top group valve stem looks bent in the photo?

Could it be the boiler is full, the OPV is not releasing and forming a hydraulic lock ?

> @"Elcarajillo"#p50384 Could it be the boiler is full, the OPV is not releasing and forming a hydraulic lock ? HX machine, so the HX unit will always be full….

Isomac Millenium - Post rebuild problems

DavecUK

chriswhite Could it be that the the diagram is incorrect and the larger 14mm valve should be used for the brew valve? The extra 2mm would then allow for the gasket

Not sure, because generic E61 groups exist, there are many manufacturers and slight variances, usually it’s best to buy group parts from the specific manufacturers. It’s why I like solenoid operated E61 groups so much. If they start letting by you can buy a Nucleus for a few euro, if the solenoid coil itself fails you can buy a coil, or an entire replacement solenoid.

« Previous Page