Hi I recently acquired an "826 / 350 Original Petromax" with extra patina. It came with an reflector screen from an old tin can that is almost rusted through - but luckily the globe was intact. 1. It is missing the pump knob - should this be steel or black (same as wheel) ? 2. The centre screw seems to be screwed on a nut on top of the fount, but when I try to unscrew, the nut is locked to the screw and spins with it. The screw does not lift out of the fount. This nut is "hidden" beneath the bottom plate and the frame. Is there any trick to loosen this without damaging the bottom plate ? - it is rusted and can be replacemed but I would like to preserve as much of the original as possible. Grateful for any input Bjørn
Bjorn, The knob should be the same as the plastic valve knob and the same color, as a rule. If you mean removing the "cage" from the tank, the cage is held on by one large screw. It holds the spirit cup, base plate, and cage to the tank. Sounds to me like the solder holding the nut on top of the tank has broken loose. If that's the case the whole thing should lift off. You will have to solder the nut back on. Once that screw is removed the whole top should lift right off.
One other thing, it sounds to me like the nut may have "dropped" through the top part of the tank making it a little difficult to get out. That could explain why the screw and nut are both moving. Try wiggling the screw around. This may increase the hole where the nut is located to slightly increase in size thereby allowing the nut to lift out with the screw.
@bjornego The piece that the screw screws into is like a hollow bolt which is put into the tank from the inside before the base plate is fitted and fastened with the small nut which you can see, it is then sealed with solder. You may have to grind off the screw head so that you can dismantle the lantern. Sometimes these can be repaired just by getting the part hot enough to melt the solder then let it cool but I think it is better to add a little more around the outside. Of course, the inside of the tank must be very clean - especially inside the top part of the tank and also round the nut on the outside. You might find it helps to solder a piece of wire to the headless screw and suspend the tank, the weight will keep the joint tight so that the melted solder does not run away. Once you have done this, I suggest you grip the short piece above the nut with one set of pliers and use another set to remove what is left of the screw. Use penetrating oil if you think it will help - you don't want to break your new repair. New screws are available. Henry.
thank you both for the input. I have found a supplier for the parts - including knob :-) So. either the centre screw or the bottom plate will have to go - a new screw head will probably distract less from the historic look of the lantern than a shiny bottom plate. I am a bit hesitant to solder on a fuel container - might have to check with a plumber - they're some of the only ones to hot-solder that I know of.
@bjornego I can understand why you are hesitant, no one wants a tank to explode ! This is why it is important to make sure that the inside is very clean and all traces of fuel are removed, you can use acetone or a cleaner/degreaser or even citric acid to do this. Personally, I use a product called POR15 cleaner degreaser but there are similar products which work just as well. Henry.
Agree with Henry, POR 15 is the way to go. I use the POR sealer to seal the tanks. Good stuff but not cheap!
I don't get that one. Depends on the age. Some lanterns where equiped with the metal pumpknob. As for the repair: try to get to the nut with some pliers or anything that can hold it, then after some wd40 or penetrating oil, loosen the bolt. make sure you still hold the body bolt in place when removing the cage. Then clean the soldering joint and solder it in place. Removing the bottom and replacing it as far more difficult. In the end not all lanterns can be saved. Clean it place a light bulb in it and hang it over the garden table, so it still has a purpose, to shed light in dardkness.
In this case I thought it would have a plastic knob and not metal one. The lantern does not look that old. Are there any numbers on the bottom of the tank?
I agree that that will work well enough if the tank is relatively clean to start with but does it get rid of varnish like deposits ? Henry.
No it won’t. However it does degas the tank and make it safe to solder etc. my go to for the varnish is warm Pine Sol. I might follow up with a little carb cleaner.
I am a bit puzzled here I thought that the p/max internal base plate which holds the cage to the collar is screwed into the top of the fuel feed as in this paper so cannot see how the screw cold be tuning with a nut ????
@Graham P What you have there is a very early example of a Petromax one-piece vaporizer. It was only used in the 1930s and in particular not for those which have the torch style "Rapid" preheater. If you look at this site of Doron Papo you will get an impression of the newer ones. In Pic. 8+10 you can see the nut/bushing that might be loose on Björns lantern. Although it is a early post-WWII 826 (without torch preheater) it is built the same way like the 828 or 829 from that same era. Regards, Martin
Success with removal of centre screw:-) I've never soldered anything except electronics with an iron, so I had to get torch, flux and solder. Some hours spent learning soldering (youtube) and the result might not be pretty, but disassembly is on track :-) Thank you all for input. As MartinK said, there is no rapid preheater, but the previous owner sat the lamp in wet concrete, so there is a lot of devris to remove on the underside of the fount, and no numbers can be read.
Good work! If it seals, I would not touch it again. I think cement can be dissolved with acid, so maybe some warm citric acid solution can help you there. It is also very good for general lamp cleaning: removing metal oxides from brass, nickel and steel. The pink colour on the brass afterwards can be removed with fine steel wool and warm soapy water. Do not leave brass or nickel plated parts in the citric acid solution for too long. Depending on the strength ( 25ml per 1 liter hot water) 10-30 minutes will be more than long enough.
You are well on the way to getting your lantern working again, The solder repair is functional and as it won't be seen when the lantern is assembled the look doesn't matter. For a neater solder repair in future apply nail polish around the joint (not on it) it will stop the solder sticking and make cleaning off the excess easier.
Great little video showing the disassembly, of an Bundeswehr 829. Your lantern is the same construction save the rapid preheater. Your tank should be brass and not steel.
Except those made for the Wehrmacht during WW2. I have and 3 2827's needing attention and one 2826 in working order.
Well. The lamp is clean and runs, so it’s working. However, it’s got a small leak and drips kerosene through the bottom seal. Looks like the solder was damaged when the lamp was taken out from the setting concrete. I have removed most of the debris and will look for some internal sealant. No numbers found on the bottom plate.
Perhaps you could try something like this: or Concrete Dissolver: An Easy Way To Clean Masonry Tools And then re-solder the bottom seal rather than permanently put in an internal sealer.
