Hello, just got my stove running and took a video. http://youtu.be/rp-C2ARkGlE Before shooting the video I replaced the pump leather and the o ring that holds the pressure in the tank. Now for the problems. After shooting the video I took my metal cup and boiled water. As it was heating I would occasionally get a small flame from where the valve screws in. This was somewhat worrisome but since it was only about the size of a match I just blew it out every time it would light and pressed on. After the water boiled I decided to step it up a notch and filled the cup with snow. The snow had melted and was starting to bubble when the real problem happened. Suddenly the pump came out as far as it goes and was covered in fuel which of course ignited. I'm guessing this isn't supposed to happen. Got the fire put out but I don't want to use it again until I get it figured out. Any thoughts? Also, please excuse any inaccuracies in the video, I only know what I've read online which could be completely wrong.
From the video, you should use more preheat. I use typically a five second squirt of liquid fuel before lighting it. You want the donut shaped cup below the burner bell to be pretty full. With enough preheat the burner goes to a blue flame immediately. It will actually start hissing before you open the valve as the fuel already in the generator starts vaporizing. [media=youtube]u38qYj4tuRc[/media] The pump problem is easily solved. Take out the pump tube and unscrew the non-return valve from the end. Springy bits will fly out so be careful. In the brass carrier is a rubber pip, this will be rock hard and not sealing properly. Get it out and replace it with a new nitrile rubber pip. These can be had from Old Coleman Parts. The M1950 and M1942 seals are interchangeable. http://www.oldcolemanparts.com/product.php?productid=728&cat=&page=1 http://www.oldcolemanparts.com/product.php?productid=504&cat=&page=1 If the seal you used for the filler cap is regular rubber then it wont last long, the fuel will wreck it. Nitrile rubber or Viton is fuel-resistant. To fit my pip I had to put it in the carrier, slice off some excess length so it was flush and then flip it around to use the smooth uncut face. Have a good clean out inside the pump tube as well. If crud gets into the valve, that can also stop it sealing. The M1942 was originally issued to the 10th Mountain Division. It was lighter the Coleman 520 M1941 that went to the regular army: [media=youtube]kS265Q8sy0Y[/media]
Thanks for the help. I actually ordered my seals from old coleman parts. I even ordered a pump check valve from them but couldn't get the nut off the end and was afraid I would damage the pump. I thought that might be the problem with the pump but wasn't sure. I went ahead and ordered a few pump seals and a few of the o rings from them so I have spares.
Sounds like you need to tighten the valve gland nut a little or replace the packing. The NRV springs are also a weak point on these. Even with a new pip it's worth testing the pump in a bowl of water. The Fettlebox will be adding a seal kit for this model shortly consisting of premium pump leather, pump clamp washer & pip (both in Viton). Provisionally the cost is going to be around £2.20.
First of all you have a great stove. I am a solid fan of the M-1942s and I carry one in my pack. The pip has been covered in the other post and are pretty much a must change. When you talk about the valve are you talking behind the knob or where the font meets valve body? If it behind the knob give the nut a little tighten. If that does not fix it you may need to replace the graphite packing. There maybe a usable one in the pump handle.
I found an M-1942 at an estate sale. This is my first stove to recondition and I have gained lots of information from the internet. I recondition sewing machines and am bringing some of that knowledge to the stove. I cleaned the stove with kerosene, as that is what we use in the sewing machine world. I also use a product called Kroil that is manufactured to be a creeping oil. After soaking the non-return valve in a cup of Kroil, it was easy to unscrew the nut. I was then able to replace the spring (taken from a pen and reconfigured), metal piece and pip. I plan to spray the pump area with soapy water to see if it is truly sealed and then try to start the stove by adding some gas to the cup below the burner. I'm still not sure where the gas will come out in the burner area and would appreciate some feedback as to what to expect. I don't see any openings in the burner area and would appreciate any feedback you have. Thanks!
A spring from a pen is probably going to be too stiff to allow the pump to work. The spring has to be a happy medium of strong enough to hold the pip sealed but weak enough to be overcome by the air pressure in the pump tube on the downward stroke of the pump. You can test if the NRV pip is sealing by putting the pump in the assembled stove (tank empty) and pumping 50-60 strokes of the pump. With that much pressure in the tank if the pip is leaking the pump handle will slowly rise up out of the tube when you take your hand off of it. Below the burner bell is the generator (called a vaporizer in the UK) liquid fuel is converted to a vapor by heat inside the generator. At the upper end of the generator is a jet, a small piece with a very tiny hole in it. That's where the vaporized fuel comes out.
M1942 is a simple stove design, like many others, lacking any safety fuel pump shut offs options other than NVR. No snorkel, check valve or pump shut off etc. As you have learned a leaking NVR can lead to fire ball! Leak at fuel valve can fire ball also. Only use them outdoors and keep in mind it's only that pip seal keeping very flammable fuel inside fount. If you see pump handle creep outward it is filling with fuel and will get past leather cup and spill out. Turn stove off first to extinguish flame and then next step is to depressurize the faunt. Nothing wrong with bucket of water and wet towel handy until you are 100% sure stove is operating correctly.
Thank you all for your responses! Since my first post, I have replaced the generator (vaporizer), sanded the pip with a fine sander to reduce the height of the pip that sticks out of the metal piece, loosened the slotted nut that holds the assembly to the tank and found an old pip in the tank. That is also where I found the metal piece that the pip goes into and makes me think that sometime long ago, someone tried to work on this stove. These old stoves are like sewing machines. You just wish they could talk and tell where they have been. Now, I have some questions: - Cottage Hill Bill, I pumped 55 strokes with the pump. The pump didn't rise out of the tank. Once I put fuel into the tank, that should tell a tale. When I installed the new generator, I could see the tiny hole in the top and see that the cleaner tip extended through the hole. That was a thrill! I'll keep you posted! - On one of sklcolorado's blogs, he mentions the correct valve assembly placement on the tank. I have managed to loosen the slotted screw that holds it down, but the valve assembly hasn't moved with gentle pressure. Is it threaded and I just need to put some Kroil on it and let it soak? I don't want to damage it and maybe it is best to leave it alone. Please advise. - I sanded the pip until it just sticks out a little. Should it be flush with the metal. Please advise. - Gieorgijewski - I didn't see any seal in the red dot area. Just the piece of metal that fit on top of it. Should there be a seal? Please advise. - A lot of the tools that I use on sewing machines work well on this stove. Kroil has been a life saver. It is a creeping oil that helps loosen stuck parts. You don't know how much I appreciate your feedback. Also, thank you for mentioning how dangerous it is to proceed without caution. I have heard you well and will strictly adhere to your advice. Susan
---- lol - it is My question to the m1942 owners... I've just purchase that stove - from any master of disaster - and i am not sure is there seal needed or not.... mean - if Yours stove is in "normal" condition and - there is no seal - then You give me the answer...
So glad I can help! It seems that there are only 2 areas that use the graphite sealing material and the advice that I read is to not mess with those areas. One is the leaver for the tip cleaner and the other is the valve that controls the gas volume. I did find some old graphite in the storage tube of my stove and wonder if it is still usable. Does anyone have thoughts on this? I have to thank the members of this site for sharing their knowledge with the others! It's invaluable!
The graphite packings in the pump tube do not deteriorate unless they've been subject to rough handling and are mashed or broken, so yes they can be safely used as replacements. The rubber gaskets and pips are usually too dried out and hard to be serviceable. You occasionally find the rare stove that has been stored in a good place where the rubber bits are useable, but it is the exception rather than the rule.
