Optimus 45 tank pressure leak

An ongoing project of mine is to re-solder the filler tube to the tank body. Every few months I get the stove out and trying some cunning new idea. It always ends in failure. The problem seems to be that I can make a lovely fillet around the the tube, with a nice concave meniscus, but air still escapes. I have tried several times to remove all the solder with a solder pump in order to remove the tube the clean it, but I just can't shift it. I am using lead/tin fluxed solder with a small gas blowlamp. Can anyone tell me what I am doing wrong, before I lose my patience and thrown it in the bin? LOL I attach a photo of my latest attempt to remove all solder to get the tube out. Thanks.

 

Have you dunk tested it to see precisely from where the pressure is escaping? Are you sure it is from the joint and not a fault with the filler cap seal?
I hope I am not trying to teach grandma how to suck eggs ..... !
Your stove, with indented filler, is likely from 1960's and I think that the filler neck is held in place by something inside the tank like a backing nut, so you cannot de-solder it and simply pull it out to clean it as you might with a pump tube.
Someone more knowledgeable will be along soon to correct me, but that would be my two pennyworth!

 

@Dean has it correct. See old thread:

Valor No.51 Dissection.

Valor 55C

Best Regards,
Kerophile.

 

Hi see my “How to” comments and others in this thread:

Advice for minor soldering job please . . .

Best Regards,
Kerophile.

 

Thanks for that. I test with a thick washing up liquid and a thin artists brush. It is the joint between the tube and the tank. Your comment about shoulder or similar inside makes sense. Thanks for that. The main leak area is at the back (i.e. innermost) area, where the tank curves downwards to make an acute angle. That's not ideal.

 

I'm a dab hand at no.13.

 

Consider a dunk test.
Cold stove in hot water. Watch for bubbles.

 

Like @Dean, I think I have a couple small stoves that might have been leaking at poor sealing surfaces between the bung top and the new rubber washer not sealing. Air leaks do not show at times, seems kero is the acid test.
Duane

 

I have noticed that blowlamp is not best tool for soldering. Quite quickly it creates a oxidation layer on top of brass and tin/lead won't stick onto joint. Blowlamp works but soldering iron would be better.

Is your solder old lead&tin solder or tin solder that is sold nowadays (since lead is forbidden)? Old solder that has 'real' lead works much better that current solders. Also old solders had much stronger/effective flux that keeps melted lead&tin to flow better that current fluxes in solders.

Here is my 45 repair work: Optimus 45 duo soldering & brazing

 

I have had stress cracks only show when the parts got hot.

 

I had a nice 00 Patent fount stove work great a few times, even snow camping, then at home one time I noticed kero on the fount, stress cracks finally showed or finished cracking. ?
Duane

 

Thanks. I have tried the dunk test and the leak is at the back where the tube makes an almost vertical contact with the tank.

 

The most powerful iron I have is only 60w. What power would you recommend? Thanks.

 

Thanks for that. It's not me being feeble then.

 

60 W might be ok if tip is filed to fit into location where heat is applied. More powerful would work better. You also can pre-heat area first with blow torch and then use soldering iron on repair area.

 

Success! It's passed the dunk test! I flooded the failed joint with some home-made liquid flux and placed a small piece of solder on top. A little heat and it looked good. The test confirmed it. If you want to make your own liquid flux just dissolve a few small pieces of violin bow rosin in alcohol (I used IPA) and that's it.

 

Well done, perseverance paid off! Looking forward to some photos of the stove in action!

 

Thanks for the flux recipe. I just bought a big old tin of Fluxite - probably dating from the 1950's or so! Just as well as I am clean out of violin bow rosin (and IPA).
Well done and I'm sorry if it sounded like I doubted you, but the tank lid seal is a very common culprit.

 

I've got to clean it up now. It looks like it's had a hard life.

 

I took your advice and changed the filler cap seal. It was a devil to get out as it had hardened, but it now has one of those new-fangled ones made from some compound I can't remember. I'm not really a collector, more a life-long user of paraffin pressure stoves. I used to travel a lot and I'd always have a brew-up on the little Shinabro stove until its burner became porous. People would often stop to look at the stove, sometimes bringing their children to see it. Of course, others would hurry past, convinced I must be mad!