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 ?

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

Isomac Millenium - Post rebuild problems

DavecUK

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

chriswhite

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

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/8h4mfmvfcxdvqlf113pqd/IMG_8252.jpg?rlkey=l0ei2nsmhtpawinxblkzzf6aj&dl=0

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.

chriswhite

Isomac Millenium E61 Group exploded diagram

chriswhite

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

DavecUK

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?

Elcarajillo

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

DavecUK

Elcarajillo 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….

chriswhite

All of the valve are straight, including thr top group one.

The new OPV arrived today with a PF pressure guage. Once installed I will report back. One issue is definately that of pressure from the boiler side forcing the boiler valve into place.

chriswhite

Well things are moving along. I have replaced the OPV and adjusted it down to around 1.0bar, as low as it can go without the valve popping out. Didn’t solve the problem of the Lever jambing against the brew valve and pressured water not being released through the exhaust valve after pulling a shot. To date I have been working off a E61 Group Head schematic that shows a 2mm silcone gasket between the infusion chamber body and the lever assembly body. The gasket was sitting visible of the infusion body and was sometimes distorting under the pressure of the hot water behind. I removed the gasket and used teflon tape to make a good seal, the body then moves up some 2mm and now the valve is being opened by the lever. Now I have pressured water being released after pulling a shot or using a blind filter!!

It seems my model does not have a rebate for the gasket to sit in (unlike that of the mushroom) and that the gasket has been the problem all along.

The brew valve is still sometimes jambing, being locked into place by water pressure. Not sure of the cause but I have ordered new pins for both the brew and infusion valves, in the hope that this will remedy the situation.

Thank you for all your suggestions and helpfull advice.

chriswhite

Thanks to everyone who has provided advice. I now can confirm that all is working satisfactorily!

Up until now I have been following an E61 exploded parts diagram for the Isomac Millenium when reassembling the machine after a big catastrophic failure. The diagram indicated 2mm silicon gaskets between the brew assembly and the infusion assembly and the main lever body.

Having ascertained that the infusion body gasket was preventing the infusion/exhaust valves to be activated, I removed said gasket and used telflon tape to provide the required seal. This had the effect of moving the valve closer to the cam, SUCCESS! the machine was exhausting after a shot.

However I was still finding that the brew valve was not being activated by the brew lever (locked in place by pressure) so tried the same trick. I removed the 2mm gasket and used tape. This allowed the assembly to be screwed together closer to the cam and SUCCESS!

I cannot rememeber if the machine was originally assembled with the white silicon gaskets but it would seem that they have been the cause of months of re-assembly pain for me! The process has however not been a waste of time. I have learnt so much more about the machine and following input from forum members has recalibrated the machine to hopefully prouduce the best tasting coffe ever!

Thanks again for the help!

DavecUK

chriswhite Photos with indications where you have removed the white Teflon gaskets and used tape would be useful to you. This is not the right way to fix the problem, which could simply be a cam follower issue.

chriswhite

Interestingly I replaced both the brew valve and infusion valves pins as well as the Stem cam having thought that wear could be the issue.

Removing both gaskets has brought the pins closer to the cam, and perhaps the new contact point on the cam is overcoming the pressure that was locking the brew valve into place?

chriswhite

DavecUK

chriswhite Put the gaskets back and unscrew the cam pins about 1 turn to take up the distance.

chriswhite

Just tried that. I loosen brew valve pin to less than finger tight and added back the silicon gasket. Turned machine on and once up to pressure (1.0bar) the brew lever jambing against brew valve as before.

I then reverted back to the tape and removed the gasket. Works again with no jambing!

As noted before i have new pins and stem cam.

chriswhite

The exploded diagram has the valve pins sized as follows.

Brew valve 12mm

Infusion Valve 13mm

Exhaust valve 14mm

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

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.