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Author Topic: Seal issues with Fleischmann 140/2 boiler  (Read 921 times)

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Seal issues with Fleischmann 140/2 boiler
« on: March 12, 2026, 02:15:56 pm »
I took on fixing up the boiler etc of a Fleischmann 140/2 for a friend of mine.  He had it as a kid, and is refurbishing it to run again.  It sat around for decades, and was rusty etc, etc.  He is working on the base and engine, I have the boiler and generator part.

So far, I have repaired the whistle, which had the threaded spigot corroded and broken, made a new valve to replace the drain valve that was missing, and put in a couple boiler bushes to replace the original corroded/damaged threads.

There are two safety valves on this.  One is the weighted one, which I have re-lapped to a decent seal, the other is a spring type that seems to use a rubber seal, so it has an o-ring now.  I think that one is likely also the fill port when unscrewed.

The problem now seems to be the sight glass seal.  That was completely disintegrated, and unusable.  I made it a new seal of silicone sheet, but that is not sealing well.  I did make it tight on the glass, so it should seal there, but I just do not know.

It's pretty difficult to see just what is leaking due to the construction of the sight glass assembly.  Plus, the sight glass was disassembled, and he does not remember which side of the inner plate is supposed to be toward the boiler.  I never really saw the original seal in complete form.

On these, one side is dimpled out at the sight glass holes, and also has a strengthening rib dimpled out the same direction. The boiler is dimpled in at the sight glass holes.

If anyone has experience with making new seals for this rather odd sight glass assembly, I could use some advice.

I will post pics in a new post, I am afraid I'll lose the text here if I mess up posting the pics.

I have corrected the model number, the model number for the unit is 140/2
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Re: Seal issues with Fleischmann 130 boiler
« Reply #1 on: March 12, 2026, 02:20:43 pm »
Pics (if they come out the right size).

I have the pressure gauge, it needs a bit of repair, and I have not yet made the tiny internal link it needs.  The pic shows a plug in place at that location.


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Re: Seal issues with Fleischmann 140/2 boiler
« Reply #2 on: March 13, 2026, 04:23:56 pm »
So, looking around the internet, I finally found a reference to this page.  You need to scroll down a bit:

http://www.ventix-pages.de/fleischmann/html/tipps.html

It is "interesting". 

It may or may not do what is needed.  For sure it does not address the sealing of the screw holes.  I will try it if I can find some suitable type hose.

But, the original seal was a single piece of some material that appeared to be a rubber.   That would have been able to seal all 4 holes, the two for the glass, and the two for the screws.   Using the suggested technique in the link would mean using some form of LocTite on the screw threads.

The photo appears to show that the plate is used with the dimpled parts fitting together.   I would have thought the thick "washers"  (2.5mm) would need the dimples facing each other concave to concave.

When I find something to use I will report back.  Maybe this, maybe not.
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Re: Seal issues with Fleischmann 140/2 boiler
« Reply #3 on: March 17, 2026, 11:50:51 am »
Well, I have searched extensively, and did find this video.  He shows the type of seal that his boiler has (along with his broken water gauge).

He has just two round seals on the glass gauge.  That seems a bit odd, since it does not do anything to seal the screws holding the gauge and cover in place.

On this one (which seems to be a 130/2 not a 140 as I was told), the screws, which are M2.5, are somewhat loose, probably due to corrosion of the brass.    They don't seal in their holes.   

The owner's recollection is that the seal was a larger one-piece seal that had holes for the screws and holes for the gauge glass. I don't know.  The linked video is the second reference to seals only on the glass, although the other source does not ahow the original seals.

I am very tempted to upsize the screws, since they are so loose, re-tapping the holes to the next size that will work with the existing hole size as a tapping size.  The metric sizes start to get a bit coarse in thread, so I am considering a US 5-44 screw size, or possible a 5-40.

At that point, I could use Loctite 542 or 242 on the threads.  The screws now are loose enough that I question the idea of sealant.  And one of the screws is a new one, so it is not corroded under-size like the remaining original screw is. It's the threads in the boiler (and the backer piece) that are corroded. 

There is still the question of the stiffening strap going in with the dimples on it fitting into the boiler dimples, or in reverse to hold a seal between the two dimples.  I have not found any video of disassembly that could show the way it is as it is taken apart.  There was a Kieth Appleton of a vertical boiler engine, but that one has sealing gobbed all around (maybe auto body filler) and so had nothing to show.  I could not see if there was also a rubber washer under the strap.



The Appleton video that shows the gauge closely

https://www.youtube.com/watch?v=BZzC18E9n3g&list=PLDV_TkPc48REWPAtopdh4Aq4YLH4P_h92&index=2
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Re: Seal issues with Fleischmann 140/2 boiler
« Reply #4 on: March 17, 2026, 04:42:45 pm »
I say 'Dimples in'
JB sealant - just a bit inside the inner area between the
glass tube and seal sheet (like smoothing a glue joint) ought to do it.
You have to assemble it first, apply the sealant as described above
and then mount it.  I've also added a tiny bit to the screws.  Just a
smidge, it will help seal and might also act a bit as a lubricant when
screwing it in.  If it looks good...

Works for me.  Then again, each time I do a sightglass is an adventure,
and not always with a good outcome.  So, you try again.

Good Luck,
Wayne
   
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Re: Seal issues with Fleischmann 140/2 boiler
« Reply #5 on: March 17, 2026, 10:33:16 pm »
That is an intersting approach.  It has potential.

But, JB Weld is not very flexible, it seems to be somewhat stiff and brittle in nature.  The boiler is thin, and will flex with pressure.  It seems that JB Weld is much more likely to leak than a rubber or silicone seal that would allow flex and expansion with heat..

Have you made that repair and had it work ok over time?
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