I’ve received my Optimus NRV removal/installation tool and, despite it being the right tool for the job, it failed to remove the NRV due to it having a very sloppy fit and rounding the corners of the business end of the NRV. I had to fabricate my own tool out of an M14x140 bolt, which then worked perfectly. Go figure. The lead washer is still seated inside the pump tube, so is it safely removed by prying out with a long screwdriver? I’d like to avoid gouging away at it in any case. Is my NRV the serviceable type? It looks to me like the cylinder would just unscrew from the NRV body but again I’ll hold off until I’m sure.
Yes that will come apart. I put the top in a small vice (the bit that fits into the tool) and then use a properly fitting screwdriver in the slot. Go carefully as they are a bit fragile. You might be able to just leave the old lead washer in place, or as you say hook it out wiht a bit of wire/long scewdriver. Don't drop it inside though...
The vice part is good advice, but I would use an old drill chuck or similar to hold the barrel of the NRV. It has happened before that the side of the NRV breaks off when using a screwdriver. If the lead washer is still a complete circle, I would leave it in place. You can always add an extra to the NRV if needed as the lead squashes into shape nicely.
I was able to take apart the NRV simply holding the end of it in the Optimus removal/installation tool very securely while unscrewing the barrel using a precisely sized screwdriver blade. #17 is now installed. The lead washer won’t come out by hooking with a bent wire so I guess I’ll leave it alone. I do have a #83V I would have liked to use, but I guess I’ll install the NRV and see if I have problems before dropping it in on top of the lead washer. Here’s how it looks now.
I wonder if what you picture is an old grey "skid mark" from a lead washer once fitted and that wasn't actually there when you unscrewed the NRV. Give it a new one anyway maybe?
That’s a good way to describe it. I’ve put the NRV back for now and am on to the next struggle. The lower vapouriser threads will not locate properly and I wonder if I’m looking at a thick stack of used lead washers at the top of the threaded area in the fount. I removed one lead washer upon disassembly (shown in the picture below). This lantern has been a curse so far but I still hope I can somehow get it working.
After about half an hour of futzing with the lower vapouriser I’ve finally got in threaded in. I’ve now installed a #83V seal along with the NRV, replaced all the parts (#196) at the foot of the vapouriser feed tube, replaced the pump leather and manometer seal, etc. I’ve given it a quick pressure test (not under water at this point) and it seems OK so far. I would light it up but I only have 250 CP mantles on hand. Is it OK to use such or must they be rated for 350/500 CP?
It might be a good idea, before using a mantle, test the burner etc under low pressure to see if it’s operating properly. See examples here: Testing burners Cheers Tony
Thanks for that advice. I’ve tested it outside without a mantle, glass or vent. I had lots of flames at first even after burning nearly two “troughs” of alcohol to preheat the vapouriser. It’s hard to know how much pressure to give when there is no manometer and the lantern model itself is unfamiliar. Anyway here’s how it burned during part of my short test (this was probably the best moment). VEED - IMG_5703 should I go ahead and dress this thing up with a mantle? If so, is a 250 CP mantle (Optimus No. 4) OK?
The flame in the short video looks good. Trying to preheat a lantern outside in the breeze without any windshield will always be difficult and take longer. "A lot of flames" would be the result of insufficient pre-heating. As for pumping, you don't need to pump any more than you have for the "test-without-mantle". I think your lantern is ready for a mantle. I'd still use a cheap one, though. Cheers Tony
A 250cp mantle is too small. As Tony says, it is a good idea to get some cheap mantles of the right size to use for testing. I have a selection of sizes I got from ebay some time ago.
I found a few old lead washers on an optimus 350 too. I ended up digging them all out and just using the new one. They were causing issues with where the assembly ended up in realtion to the collar. Rest assured you are not alone and we have all been there. The main thing is you are learning and overcoming !
I appreciate the recent replies and comments, they’re very helpful. Does it look from the picture I provided like there are still some old lead washers on top of the tank? All I can say is that the lighter colored metal there is soft and makes it a bear to thread the lower vapouriser into the internal threads. I test burned the lantern indoors today without a mantle, glass or vent. I kept a close eye on it as it ran on low pressure (I cycled the pump maybe 10 times). It ran decently, with the exception of a couple of minor blips, for around 10 minutes before suddenly bursting into flames. No bueno. I can’t think of anything that would cause this besides somehow getting too much fuel. If kerosene is being delivered faster than it can all be vapourised, I suppose some of it leaks out onto the inner casing and then ignites. If that’s what’s happening, does it mean the jet is worn? I don’t see how the needle could be at fault since the pricker wire is intact and it’s tightened securely to the carburetor rod. Edit: On second thought, might it be that the possible presence of extra lead washers under the lower vapouriser is causing the gap between the jet and the air tube to be too small, thereby resulting in an overly rich air/fuel mixture? I do have a new 250 CP needle and jet as spares for another lantern, but I’d be willing to use them on this one if they’re compatible and might fix the problem. I definitely don’t want to fit any mantle, even a cheap one, until the lantern can run trouble-free for an extended period.
Yes - with no mantle the vapouriser does not stay hot enough to turn the liquid into gas. Time for a mantle ! I would remove the old lead washers and start afresh - with only one like when it came out of the factory. Nearly there !
I’ll accept your expertise here, but, because I still want to learn more, can I ask how it is that these lanterns can be used as a heater (with one of those radiator and protection plate setups) without such problems? In that case, no mantle is used. Does the radiator just work to centralize and contain the heat so that the vapouriser stays hot enough to gasify all the incoming fuel?
And 15 minutes of digging has brought me here! Thank you, Fireexit1 I do wish I had plugged the hole with something as I’m sure there are now bits of lead shavings in the tank. As I write this, someone just brought a couple of old Golden Globe 500 CP mantles to the door, so it looks like I’ll be lighting up the Optimus tonight!
They do have a mantle of sorts - it tends to be a wire mesh or metal sheet with holes in it. If you think about it it is doing the same job but with heat in mind
I had already inquired about using 250 CP mantles and learned that they’re too small. Is it true that 500 CP mantles will “shrink down” to work properly with a 350 CP lantern?
It’s up and running. I am getting a substantial halo around the mantle, though. This is with just over 500 ml of fresh fuel and a total of 30 pumps. Does this suggest too much or too little pressure, or a bad jet? In the way of options I now also have a new 500 CP jet and needle in addition to the 250 CP set I mentioned earlier.
That does look like a worn jet. I would try pumping it a bit more first tho. The number of pumps is dependent on condition of pump/ nrv and how much fuel is onboard.
I don’t know if I should use the manometer from one of my other lanterns on this for now or what, but I just don’t have a comfortable feeling about the operating pressure. I don’t want to end up with a ballooned tank like you see on modern Tilleys if you know what I mean. If I switch out the jet and needle, is it OK to use the 500 CP set?
yes - but watch the needle/jet fit. The 500 needle might be longer so require adjustment of the operating rod. I think the Optimus manometer is a different thread to the petromax.
Good points. I knew to watch for the needle height after swapping parts. The manometer from my Hipólito 250 has the right threads for the Optimus.
I would light it up again using the pressure guage (not that they are horribly accurate) - count the pumps needed for next time
If you can do that with one of these tanks I will be impressed. I usually pump until my thumb hurts. How long had the lamp been lit when you took the photo. It does take up to half an hour for a mantle to 'settle in'.
Now I’m 100% satisfied with this old Optimus! You guys are always spot on with the advice. All I did was remove the jet and needle and soak them in my leftover citric acid bath for half an hour, give them a quick toothbrushing and rinse, reinstall them and tighten everything down. I installed the pressure gauge from my Hipólito and, after lighting it, gave it 80 pumps until the pressure reached just past the red line. No more halo whatsoever! What’s strange is that this is pretty much how things went with a Tilley Guardsman I just restored. Maybe it’s just kind of “normal” that you get an inferior burn quality for a while after a new mantle is burned in. This hasn’t always happened in my experience, but it’s useful for me to have encountered this and worked through it. This is by no means the most beautiful lantern I’ve seen or used, but it now means a lot to me as I’ve literally gotten to know every single piece of it and put a considerable amount of time and thought into it. The sound it makes is so cool. Very throaty. I’m sure thankful this forum exists. As we say in Finland, kiitos ja anteeksi
Glad you got it sorted. These lamps usually work well and are reliable. The only complaint I have with them is that the spirit cup is too low to give a satisfactory pre-heat. I often have to do it twice. Miksi anteeksi?
Yes, the spirit cup is set awfully low. I have taken to preheating twice anyway since that’s what the basic Petromax instructions call for, even on models with the higher-set spirit cups. I don’t know how much effect the little flame tube has on preheating, but it sure looks cool in the process. The going price for methylated spirits here (we use Sinol in Finland) is 7€/l so filling a big dish twice every time the lamp is rather expensive. I’d still rather preheat twice than risk a flameout on any Petromax-style lantern. The anteeksi part is rather hard to explain in this context. Sometimes when we thank someone and say kiitos, it almost seems that we should also be apologizing (anteeksi)—for asking so much of people when we aren’t very knowledgeable of seemingly basic things, etc. Yet we manage, year after year, to be regarded as the world’s happiest people , despite an obsessive overanalysis of every social interaction.
