AssafL wrote:LM should do a special deal on all the plastic boxes. The display/keyboard, the drain, and the brain. They all fall apart after a few years in the heat....

I didn't mention my brain box falling apart because I've removed and opened/closed mine many times, which hastens the deterioration. Users who haven't had leaks and don't do mods probably won't have problems with the brain box falling apart.

AssafL wrote:What about Viton?

Also - in the thread about Cafelat Silicone Group Gaskets Paul Pratt recommended using Dow (which is Silicone based). I was intrigued by that.

I think that anywhere inside the GS3 - Dow or Superlube should be used. No Petroleum (I am saying this from - shamefully admit - experience).

I don't know why they recommend these things, I simply know from experience that if you use silicone based lube on silicone o'rings/seals they deteriorate (swell/soften) and you should use Petrolium Jelly (or similar). Silicone based lubes are fine for rubber. Viton is not a silicone based rubber and generally tolerates hydrocarbons OK, so Petrolium or silicon based would be fine. Of course you need to be careful as a lot of parts sold as Viton are not Viton, so it may be safer to always use a silicone lube in case.

If you doubt what I say, simply look it up or talk to any friends who do scuba diving.

DaveC - I don't disagree. I know this from Pneumatic brakes which can suffer the same catastrophic failures that (I guess) a scuba diver can encounter.

With lubes you have the o-ring type, medium chemistry, and lubrication chemistry. All three should be completely impervious to each other.

Matt - My guess is any technician that services shops can service your machine. I would gladly try to help but I am too far away (Israel is more than 2 hours drive from Chris" Coffee .

Why does your machine overfill? Can only happen if the board is underwater or a check valve is stuck open. Did you figure out what is causing it? If it still works, you don't need a replacement board. Even if the board has issues, it is repairable. Unless the Atmel is fried, you should be able to get more years out of it.

BTW - There are very few fittings on the LM for which a thread sealer would help (eg the milk frothing tip can use PTFE sealer) so my guess is either the fittings are not well aligned, ithey aren"t sufficiently tightened or you are not tightening using two spanners.

Matt - searched back to the last issue when you were stabilizing the machine - seemed like the RTC Battery was the only issue you had - that is a welded 2032 battery. They are less than a buck....

What you must figure out is why it overfills. That is concerning since erratic behavior many times indicates a short. Either water or something else. The sensor just touches the water and the water shorts it to ground. For it not to work, something is messing with the pull-up.

Matt - since the error displays went away when you dried and cleaned the board - and now they are back - it means the board is probably being contaminated.As Dick warned in the other thread - your board is at risk.

You may not see the leak: For example the leak may be near the steam tank, and evaporates. But when the machine is turned off, and cools down a bit, the leak no longer evaporates and works its way along the cable to the controller. There are always signs like crusty deposits, verdigris or black oxidation, or something similar. I've even used thin tissue paper and a flashlight for find a leak.

Is what is being called the OPV here the same thing that La Marzocco calls the Safety Valve in their parts catalog (p.33 Item 4)? I suspect so but just want to make sure. I traced a sputtering steam release into the tray to it so I assume that means it is failing and needs replacement.

You mentioned sputtering in the tray - that is unlikely to be the OPV. More likely it is item 14 - the vacuum breaker. It has a relatively short(er) life as it keep sputtering boiling water (as it closes) which leave a layer of mineral deposits - which accumulate over time and eventually prevent it from sealing well (it will continue to hiss and sputter but never fully seal).

As to your question: Yes - item 4 is indeed the OPV. If the steam boiler pressure increases above the OPV pressure - the OPV will release the excess pressure. Note that is doesn't have to be runaway thermals to get the OPV to pop. A stuck open fill valve or stuck open check valves in a plumbed in machine will cause the mains pressure (many times 3 bar or more) to drive the OPV open - at that point the OPV becomes a gusher and is one of the reasons that a plumbed in machine should also be connected to the drain.

The main difference between the OPV and the vacuum breaker is that the vacuum breaker is open and closes at a specific steam pressure. An OPV will open above a specific pressure to relieve excess pressure. When both are used in the context of a steam boiler, the rated pressure needed to close the vacuum breaker will be always lower than the working pressure, whereas the rated pressure needed to open the OPV will always be higher than the working pressure.