Post By Lyrebird
Post By MorganGT
E61 group valve gasket interchangeability.
Possibly an abstruse question, but does anyone know if the "valve gaskets" inside the E61 grouphead are interchangeable between brands?
I'm refurbishing a VBM which appers to have suffered 8 years of poor maintenance: I've finished the grouphead except for these seals, two of which are starting to decay. I can find ones for Expobar and am wondering if they are all the same size. Of course they are so cheap I can just order them and try it but if anyone knows that they won't fit and has a source of ones that do that would be a help.
They are interchangeable, however 50 % chance that you will snap the top when you try of unscrew it. Look at the tare and ware of the brass, always if is a ware you better of replacing the valve
If you're interchanging the whole valve and not just the actual rubber gasket part, be aware that their are 2 lengths of the infusion/preinfusion valve (Middle valve), that I know of. The VBM uses the longer of the 2. I was once sold a shorter one that doesn't work in the VBM but was for a Rocket machine I believe. As far as I know the brew valve and drain valve are the same on most E61 groupheads but am happy to stand corrected if not. Keep the old ones to check length of replacements.
I think on most older machines trying to dismantle these valves to replace just the rubber gasket will usually end in snapping off the threaded spigot but if you're not using the machine just try some gentle heat on the longer brass leg of the valve before trying to unscrew. There's nothing to lose in trying but just keep the pieces together for your length checking of new valves when needed!
(scroll through to valves - http://coffeetimex.wikidot.com/e61-group-servicing)
The Cafelat 8mm Red silicone E61 Grouphead gaskets work well in the VBM and perfectly centre the portafilter handle.
Last edited by CafeLotta; 28th June 2018 at 05:01 PM.
Thanks for the tips.
BTW I must belong to the other 50%, and no heat needed.
There are a variety of different configurations and lengths of the actual brass components of the valves, but the actual rubber seals are all interchangeable across all variations of the E61 lever group.
And they are actually the same as the tap washers used in older Rancilio taps, and all La Marzocco taps (except Linea Classics).
For me about half the time a gentle turn using a tiny shifter will undo them, when this doesn't work I give the valve a 5 second blast with a blowtorch which softens the coffee oil that has seeped up the threads and set like tar, and they can usually then be unscrewed by hand.
That's caused by oxidative polymerisation: like most fats of vegetable origin, coffee fats* have double bonds (= unsaturated) so they will polymerise in the presence of oxidants. Since the "tar" that is produced is chemically similar to paint** it can be removed by the same types of processes: caustic is your friend.
Originally Posted by MorganGT
As per the post above, I've already disassembled them, I just wanted to know whether I needed to look further afield for replacement
* About half is linoleic acid, so called because it was isolated from linseed oil.
** Old fashioned oil paints were based on fats which polymerised easily, such as linseed oil or tung oil.
Last edited by Lyrebird; 1st July 2018 at 10:25 AM.
I can now answer my own question: they are not completely interchangeable. The valve gaskets listed as being for Expobar have a slightly smaller OD than the ones for Vibiemme.
Last edited by Lyrebird; 14th July 2018 at 10:25 AM.
They are actually meant to be the same size, all applications of that seal are specified as 13mm x 4mm x 4mm, but can vary slightly due to differing materials being used to make them as different materials shrink at different rates after being moulded. Unless the maker calculates this precisely and makes slightly differently oversized moulds for each type of material used (Viton rubber, EPDM, silicone etc.) you end up with slight variances in size, sometimes even within batches of the same material.
Originally Posted by Lyrebird
Sometimes I rebuild a set of valves and find one seal will drop into place and is loose enough that it would fall out without the nut securing it, another pushes easily into place and will hold itself secure, while the third one needs extra persuasion to push it into place.
The ones I bought were consistently 12.85mm OD, I've ordered some 13mm OD ones.
I'm in no hurry as it looks like the Gicar autofill controller is dead so I am presently designing a replacement.