Restoration of a 1963 Faema Lambro [Finished] - Page 13

A haven dedicated to manual espresso machine aficionados.
User avatar
IamOiman (original poster)
Team HB

#121: Post by IamOiman (original poster) »

I pulled one more shot today, it was a little overextracted but it was essentially liquid caramel.



However that is not why I am posting. I found the source of the hissing, on the t-fitting for the water inlet and hot water solder joint. A pinhole leak :x (the greenish area right below the brass blob) . It is not consistent, often there is no hissing (even at operating pressure) but there are times where there is hissing and tiny bubbling occuring at various pressures but not room pressure. I noticed it specifically after I turned off the Lambro for the day and was observing it depressurizing. No water escapes from the hole and evaporates instantly when it does occur.

I am almost afraid to ask if I need to take off everything to address this, it is a very small and not constant however I am not really wanting to do something like a jb weld fix if that is not really a good solution. Loctite 290 keeps popping up in my head though for something so small. Or perhaps I let this tiny hole seal itself with scale? It can't be more than 0.5mm in diameter


To quote a certain Barry on Loctite 290
barry wrote:I'm talking about a drop of the stuff, only a tiny portion of which would have water contact. I've ingested more than that in the course of using it over the past ten years... (it has a slightly sweet taste, btw)

As for strength, I recommend through experience, not through data sheets. I've used the stuff on several occasions for espresso equipment. Originally, I used it for sealing thermocouple wire penetrations into portafilters (holds just fine against 9 bars). I have used it a few times as a penultimate mend for tedious pinholes or fissures in brazes (the ultimate mend being disassembly and re-brazing). Sometimes it works, sometimes it doesn't. Again, it's worth the try if it means not having to take a machine completely down to take the boiler to the welding shop.
I also have this old vid from OE discussing it as well. In my case it's one pinhole (though I am looking around the joint for any other ones potentially)
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

Versalab: maker and supplier of finest espresso equipment
Sponsored by Versalab
User avatar
IamOiman (original poster)
Team HB

#122: Post by IamOiman (original poster) »

Just to give perspective on the size, the hole is in a little 1mm divot that is maybe .25mm across if I look at it now. Brazing or related would definitely fix the issue but it just seems like overkill for such a tiny leak? The rest of the joint looks sound after inspecting the photos, but of course looks can deceive.

I am just concerned with damaging the t-fitting if I take the brazing route. I'll admit I never was able to get it out, it was plugged beyond belief. I can take off the pipes and everything but I'd never forgive myself if I mess up that t-fitting

-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
civ

#123: Post by civ »

Hello:

Congratulations, it's looking great.
That chrome job is really fantastic ...
IamOiman wrote: Brazing or related would definitely fix the issue ...
Indeed ...

The hole is so small that I don't really think you would need to braze it.
There is (apparently) no structural damage, it's just a pinhole leak.
A nuisance which may or may not get (eventually) filled with scale.

But scale would not be a solution for me, nor is epoxy/anaerobics, bubble gum, etc.

If I were you, I'd fill it with solder of the type which has a lower melting point than the one used on the boiler.
ie: depending on the existing stuff, thin flux core solder for common electronic work or thin silver solder with a lowest melting point you can get.

The process is simple (to explain): take off all the adjacent piping (so it does not draw heat away from the work area), give the area around the hole a thorough clean-up with a soft brass brush and then degrease it with acetone.

You will be filling the hole using good quality flux and a hot torch with a concentrated flame.

It is necessary to take the area where the pin hole is up to the proper temperature slowly and remove the heat as you see solder melt and flow into the hole. Do not linger unnecessarily.

Yes, it takes practise.

It will be a good thing to previously warm up the boiler area around the fitting as much as you can.
And if you can figure out how to get a bit of a vacuum in the boiler it would be a plus as the solder would get sucked into the hole.

Now, this is precision work: you do not want to overheat the existing area and mess up the solder already there so you have to be careful.

That's about it. 8^D

Best,

CIV

User avatar
NelisB

#124: Post by NelisB »

How do you get those beautiful water drops gently dancing from your shower screen? I get a boiling flood that ruins my puck most of the time.

turboyeast

#125: Post by turboyeast »

LS.,
This project is looking great. I like the solution as proposed by CIV, this will work.
However, there is another option. Do as described by CIV, however, clean the pinhole thoroughly with diluted citric acid (20% or so).
Make sure that you clamp the t-fitting so that it cannot move in any direction!!! Take your MAP torch and carefully start heating the solder. Once you reach melting temperature, the pinhole will close automatically.
This will only work on 2 conditions: 1) cleaning with citric acid, 2) clamp down the fitting.

Cheers, TY

User avatar
IamOiman (original poster)
Team HB

#126: Post by IamOiman (original poster) »

NelisB wrote:How do you get those beautiful water drops gently dancing from your shower screen? I get a boiling flood that ruins my puck most of the time.
The shutoff valve on the bottom of the group can be partially closed and just reduce the flow rate of water entering the group to achieve this. Somewhere around here Dominicio posted about it, I think in his shower screen thread.

There is also the suggestion to take a small punch or screwdriver to gently strike it once near the hole to push the solder a little to block the hole. I have a few options it looks like so I'll see what is appropriate
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
civ

#127: Post by civ »

Hello:
turboyeast wrote:LS.,
... clamp the t-fitting so that it cannot move ...
Yes that would work and the pinhole would close on itself, solving the problem.
Albeit with the (high) risk of the fitting moving or becoming unsoldered.

Short of brazing the joint, to do as you suggest would be the next best thing but it needs the hands of someone with enough practise and experience in soldering open/butt joints or an unexposed solder joint where the pipe is held in place/position not by solder but by a receiving fitting.

I'm not an expert by any means but in my opinion the risk is too high for fixing a small pinhole leak and Ryan may not have the needed skills to carry out such an operation.

The other solution would be to unmount the boiler and have the joint unsoldered and brazed.
Given the size/mass of the boiler, it's an oxy-acetylene job for sure.

And a good opportunity to redo all the joints with silver solder, but that's more $$$.

Best,

CIV

ECM Manufacture: @ecmespresso #weliveespresso
Sponsored by ECM Manufacture
User avatar
Jake_G
Team HB

#128: Post by Jake_G »

Not that Ryan doesn't already have enough advice on this particular issue, but were it mine, I would be inclined to drill a blind hole a few mm into the pinhole the same diameter as some silver solder I had on hand, then brush some flux into the wound and place a stub of solder wire into it with a few diameters sticking out.

Then I would apply localized heat around the hole with a benzene torch or similar until the plug of solder melted into the hole.

It would not require too much heat. And would be a done deal with very little risk of dislodging the tee fitting.
LMWDP #704
★ Helpful

User avatar
IamOiman (original poster)
Team HB

#129: Post by IamOiman (original poster) »

I believe I will try to go for the lower temp lead free solder as a solution since this will not be supporting the fitting but rather just focusing on the tiny pinhole. I was thinking something like this for the material, about 430F melting point. If I do this method I will try it first myself. I'll scrub off the surface of any scale/debris with scotch brite, wipe it down with acetone, then use a hand solder tool I have on hand to do the job and see if I need to escalate from there.
https://www.acehardware.com/departments ... ries/27155

The only question I would have is the cleanup of the flux after. I presume I would need to cycle some water in the boiler to clean it out or will it just burn away?
-Ryan
Using a spice grinder violates the Geneva Convention
LMWDP #612

User avatar
civ

#130: Post by civ »

Hello:
IamOiman wrote: ... go for the lower temp lead free solder ...
Don't worry about the lead.
It won't come into any significant contact with the boiler water.
IamOiman wrote: ... scrub off the surface of any scale/debris with scotch brite ...
Scotch brite won't do, you need to get into the hole, so to speak.
Better to use a hard-ish mini brass/steel brush and use it lightly till you get what you need cleaned up.
Like these:


Image courtesy cameduae.com
IamOiman wrote: ... use a hand solder tool ...
No.
That tool does not have enough energy to heat up a lump of material like that one.

You need a MAPP type gas and torch with a focused flame and get the surrounding boiler area as hot as possible before you try to melt the solder.
Otherwise the heat will dissipate and while some solder may/will melt, it will not bind properly.
This will get you what a is called a cold joint due to incomplete wetting.
IamOiman wrote: ... cleanup of the flux after.
Not a problem, the flux will stay on the outside of the boiler or get burnt off.
You can cycle some water if you want to have peace of mind.

Best,

CIV