Problem is the piston shaft is rusting at its base and is beginning to jam and stick when it moves through the collar when the lever is pulled down.

Is there a food grade rust preventative/lube to use on the piston shaft to treat and prevent rust?

Machine is a vintage Bezzera La Familia with a group similar to MCAL. It uses MCAL seals on the piston and the seal grooves are built up with Teflon tape to make the MCAL seals...well...seal better.

Water leakage into the upper part of the piston is rare, but does happen.

All parts are either brass or stainless except this damn shaft.

Also, as you can tell in photo, access is extremely limited through the spring. I can use a pick to flake off the rust residue that is jamming it.

Olive oil?
Petroleum jelly?

-Jared

Chunks of rust scraped off.

Dow Molykote 111 is a great food-grade lubricant for espresso machines. If this were mine, though, I'd want to disassemble it, fix the problem and thoroughly clean it up rather than just picking off rust and applying lube.

wsfarrell wrote:Dow Molykote 111 is a great food-grade lubricant for espresso machines.

I use the Dow 111 on the seals. I've never seen these pistons disassembled before. I'm sure there is a way, but would require carefully compressing the spring somehow. It's under quite a bit of load. I wonder if the piston is screwed into the shaft...hmmm

To remove the rust you could place the whole assembly in molasses diluted 1:10 with water. It does a great job at removing/converting rust (contains low amounts of phosphoric acid and chelating agents) and is non-toxic. It might take a few days though. After that washing with warm water drying and apply something like DOW 111. A cotton swab might help getting it between the spring.
Cheers
Rob

That is likely due to steam getting past the seal. I would replace the top piston seal as part of this repair, and then pull the assembly every 3-4 months to check on it. I had a similar issue on my commercial lever and was only able to resolve it by sourcing silicone seals that didn't have such a rapid failure rate.

Get some Evaporust, soak the affected parts overnight in it, and that will completely remove the rust. You will need to build some sort of compression jig to remove the piston from the spring assembly. I made one out of a 1" plywood square and threaded rod.

You could use electrolysis to remove the rust and not disassemble.

https://www.instructables.com/id/Electr ... aka-Magic/

grog wrote:That is likely due to steam getting past the seal. I would replace the top piston seal as part of this repair, and then pull the assembly every 3-4 months to check on it. I had a similar issue on my commercial lever and was only able to resolve it by sourcing silicone seals that didn't have such a rapid failure rate.

Get some Evaporust, soak the affected parts overnight in it, and that will completely remove the rust. You will need to build some sort of compression jig to remove the piston from the spring assembly. I made one out of a 1" plywood square and threaded rod.

Good advice.