I am talking about the big green two burner stoves that burn liquid fuel (white gas). I have several of these. What got me started working up this page is putting my model 425E back into service.
I haven't used JB Weld on a Coleman Stove ... yet, but I wanted to put this information someplace:
For any number of reasons, I prefer the liquid fuel stoves to propane stoves, maybe top on the list is the waste of all those bottles you aren't supposed to refill. (technically you aren't supposed to refill and then transport them). But here is a quick note on filling those 1 pound propane bottles:
If you do this, the big danger is overfilling them, and the best way to be sure you don't do this is to weigh them. Enough about this.What this valve does is select two ways to get fuel from the tank. When in the up to light position, fuel is taken from up high, where there is nothing but air plus vapors. That is unles you have gone to crazy pains to overfill the tank. Later when the generator is nice and hot and you flip the lever down, fuel is taken in liquid form from down deep in the tank, and the generator is hot enough to vaporize it.
Do not try to disassemble this valve. I don't know how to do it, nor have I found anyone else who does, nor have I found a need to do so.
Also, my advice is never to tip the tank when filling it to get it extra full. Set the tank on a level surface and fill it as much as that allows. This will ensure that there is plenty of room for an air/gas mix in the top of the tank.
I have used this stove off and on ever since I bought it at a yard sale, perhaps in 1980 or so. In May of 2017 it stopped working (we are talking 37 years of use under my ownership). Taking it apart, I discovered that the generator was a fused mass of black carbon. The "spring" was solidly welded to the central rod. Most people would just buy a new generator at this point, but I got a needle (a dental probe like gadget with a handle) and began chipping away. After an hour or two the central rod could be pulled out of the spring and then cleanup was easy using a tiny file and wire brush. The tiny pin on the end of the rod was bent (perhaps very recently when I tried a quick field disassembly), but I was able to carefully straighten it and reassemble it all. I took this opportunity to check the function of the check valve (it works fine) in the tank pump mechanism). Refilled with fuel it seems to work quite well. It is nice to do a zero dollar repair on something like this and perhaps I am good to go for another 37 years.
The printing on the stove specifies generator part number 412-5621 (which is the same as for my model 425C)
It doesn't run right. A gassy flame comes out of the air manifold while the burner is running. The rod comes out of the generator nicely, but the spring is welded inside of the generator tube. My guess is that getting the spring loose and cleaning it up would solve the problem (or a new generator).
There are several tips for removing a spring stuck inside a generator tube like this. One is to get a heavy guage paper clip, straighten it, and put a small 90 degree "hook" on the end. This can be used to insert and yank on the generator spring. In my case the clip simply straightened out.
So I fought with vise grips and penetrating oil (see below) until I got the generator out. This chewed up the tube a fair bit, but not in any way that would keep it from working. Being concerned about cosmetics, I chucked the tube in my lathe and used a file to remove all the chew marks and restore a nice appearance.
Then I clamped the generator vertically in my vise and heated it with a propane torch. Do this with good ventilation. Once it was good and hot, I dunked it quickly in a bucket of water. After 3 repetitions of this, I was able to drive out the spring using some 3/16 brass rod I had handy.
The spring in the old 425C generator is different than the one in the newer 425E. The 425E spring is evenly wound and runs the entire length of the tube. The 425C spring becomes more tightly wound in the area where it gets hot and stops an inch or two short of the end of the generator. It fits tightly enough in the tube that it does not slide around. My bet is that it is simply cheaper to use an evenly wound spring and works just as well. Note that both of these stoves specify the same part number for a replacement generator.
When reinstalling the tube be very very careful not to cross-thread the fine threads! Once back together this stove burns much more nicely, but I still get a flame from where the generator enters the manifold. I need to check the manifold for obstructions.
Older stoves with original parts have a leather "cup" that needs to seal against the sides of the pump cylinder to generate pressure. In an older stove, this tends to either dry out or to shrink. The first thing to try is putting oil in the hole maked "oil", but if you are dealing with an old leather cup that hasn't been used in a long time, this probably is not going to work.
One option is to replace the cup (and perhaps the whole mechanism as part of a "kit"). The new kits have a neoprene cup that won't dry out, but it will definitely need oil on a regular basis. The other option is to pull out the old cup, stretch it out so it is essentially inside out, almost like an umbrella. Then soak it in oil. This may get you going, but is not a long term solution.
I have found the new kits with a neoprene "cup" for the pump to be all but worthless. They work for a short time, then the cup shrinks or takes a set or something and no longer works. What you can do for one evening is to disassemble the pump in the field, stretch the cup by hand, oil it, and cross your fingers.
What I recently did was to find a fellow who is hand making replacement leather cups. I ordered a 3 pack (for $13) and was very much satisfied, these are very high quality. I replaced the all but useless neoprene cup with these and it is amazing.
The listing says: Coleman 216-5091 EquivalentThe truth is that if you use one of these stoves, you should carry a few items to service the pump in the field. A screwdriver and small bottle of oil would solve most commonly encountered problems. If you have cronic problems, but the leather cups from "Coleman Creations" and upgrade your stove.
Of course, there are forums and websites devoted to Coleman (and other classic) stoves. And, as you might expect, there are people who collect these things and fret over model numbers and dates of manufacture.
I am pretty sure most people don't do what I do, when they have trouble. They just buy and install a new generator. Even that is not easy if your generator is all but welded into the valve assembly (as every one I have yet to work on has been). However, you may not need to remove the tube. When I repaired my 425E, the rod was glued to the "spring", but I was able to remove them, separate the two and clean them up, then reinstall them without removing the tube.
I will note here that the inside diameter of the 425 generator tube is just a bit over 0.22 inches. Just right for a 22 caliber gun cleaning brush.
As near as I can tell, the whole purpose of the "spring" in the generator is to slow down the gas and provide a tortuous path. This ensures that liquid gas does not make it out the orifice end of the generator, but has to linger in the "hot zone" long enough to be vaporized. People rehabilitate generators by wrapping the central rod with brass screen or wire, and apparently that works pretty well.
I have never needed to do anything of this sort. The spring in a stove generator is a heavy guage item and looks virtually indestructible.
In the case of my 425C, the spring was glued into the tube and it was necessary to remove the tube so it could be heated with a propane torch. I used a small set of vise grips along with Kroil penetrating oil and a certain amount of patience letting the assembly "cook" in the hot sun. Time is your friend with stuck bolts and penetrating oil.
If you don't have Kroil, consider "Power Blaster" or the famous home-brew mix of Acetone and ATF. Reportedly a 50-50 mix of ATF and Acetone has been found to be superior to every commercial product. Here is the data, which indicates the torque required to remove a "scientifically rusted bolt" after the application of various products:
Nothing ................ 516 pounds WD-40 .................. 238 pounds PB Blaster ............. 214 pounds Liquid Wrench .......... 127 pounds Kano Kroil ............. 106 pounds ATF-Acetone mix .... 53 poundsSupposedly the above data was reported in the April 2007 issue of "Machinist's Workshop" magazine. I have also heard that the original concoction was a mix of acetone and brake fluid. Also a mix of Kerosene and ATF is advocated by some. See also the following link:
Tom's hiking pages / tom@mmto.org