Glad you could join me once again for yet another installment of restoration tutorials.
This one is called...
Today, we will repair & restore the excellent U.S. military appliance known as the Coleman Model 520 Military Burner. I've also seen it referred to as the U.S. M-1941 cooking stove. First, let's have a look at our subject:
Let's get started. We first unscrew the burner head from the vaporizer...
then lift it out.
Unscrew the jamb nut...
and remove it.
Carefully lift the vaporizer up and off, being careful not to damage the cleaning rod & needle.
Now, I have to say that I ran into a bunch of trouble when working on this stove. Here was the first problem - the tip cleaner stem was seized up tight. Normally, at this point you would turn the tip cleaner stem straight up, in order to be able to remove the locknut and cleaning rod/needle. Since it wouldn't move, I had to leave it in for now. If I would've tried to force it, the stem would have snapped right off. When this kind of thing happens, you must be careful unless you want to end up with broken, useless parts.
This brought me immediately to the next disaster. In order to remove the valve assembly on this stove, the valve stem & packing must be removed first. Unfortunately, the valve stem, like the tip cleaner stem, was completely frozen tight! Could not budge it! What I decided to do here is to first remove the valve wheel, then heat the packing nut & valve body with a propane torch. Then, using a rag saturated in cold water, quench just the stem, and quickly attach the valve wheel and try to open the valve. After 3 or 4 times, it finally snapped (yes, in a good way, whew!) and opened up.
Now, I loosened and unscrewed the packing nut...
and removed the valve stem.
Next, I removed the pump cap, and lifted out the pump.
Now, when attempting to unscrew the fuel cap, I ran into the next disaster - you guessed it - stuck again! This time I just wrapped a piece of leather around the cap and twisted it off with pliers. Thankfully, no damage! However, you can see that the cap insert, as well as the tank fill are badly rusted - not a good sign of things to come.
This stove is a bit awkward to dismantle because the entire frame is held on by one lock nut which is threaded onto the valve. So, the valve has to be removed before the frame, and you have to work through & around a frame that is loose and flopping around. So, first, we have to loosen the lock nut:
Had to remove the chain that retains the fuel cap.
Now, we unscrew the valve from the tank. To add to the awkwardness described above, don't forget to count the number of turns that you unscrew the valve, so you can put it back to the proper depth, later!
Lift out the valve.
And, finally, the frame!
Next problem. I'll bet that you think that this is a pretty nice looking tank:
Well, here are a couple of other shots:
Each of those areas (among MANY others) leak. I'm not talking weeping, here. I'm talking sieve, colander, spaghetti strainer! Add to that - I shook out what appeared to be half a pound (0.227 kg) of rust, much of it in quite large chunks! Whatever thoughts I might've had about POR-15 treating this tank, disappeared at that point. Those of you who would entertain the notion of my "giving the tank sealer a try on this one", don't even bother! It AIN'T gonna happen!
Here's is the valve assembly cleaned and mostly assembled. I have to explain myself, in that I immediately ran into yet another disaster - the F/A tube was badly corroded, and the inner fuel tube actually snapped off from corrosion. I attempted a repair of it, and we'll have to see what happens when I try to light it. But, at this point, I was so disgusted & disappointed, that I stopped taking any photos of those repair efforts. I'm sorry for that.
You'll remember earlier that the first problem I ran into was that the tip cleaner was frozen in place. So now that I had the valve out, it was time to address this. So, after I removed the valve assembly, I heated the tip cleaner portion of the valve with a propane torch, then loosened the packing nut, then heated some more, and gently tried to move the stem back & forth. A couple of alternating heats & tries did the trick, and it freed up! Here is what the cleaning rod & locknut look like:
The inside of the vaporizer, complete with screen. Yes, I did remove the screen & clean it. What a bear it is to get it rolled back up to fit inside the vaporizer. I don't know how our soldiers ever accomplished that in the field. They were better men than I am!
Carefully lowering the vaporizer back into place, so as not to destroy the cleaning needle!
Installing the jamb nut.
Some photos of the cleaned & polished burner head...
and the frame.
Now, it is time to begin reassembly. I bought a replacement tank from one of our fine members. The most important thing is that it was solid, with no holes or leaks! Some rust on the outside, though, and plenty of rust - along with the dreaded "black nasty" on the inside. I cleaned out the black nasty with oven cleaner, and the rust with CLR, then BBs & denatured alcohol. I was amazed! After getting all of that crud out of there, the inside of this 72 year old tank looked almost brand new! The black nasty & rust coating must've acted like a sealer. No pitting on the inside (that I could see)! Because of my track record with rusted out military tanks, I decided to POR-15 this one, in order to keep this soldier going for another 70 years! I then stripped the paint, removed the rust, and repainted the outside. Here's what she looks like...
You can even still see the (unbelievably lightly stamped) I.D. stamp...
...which is the same exact year as the original tank - so originality is maintained. I'm kind of proud that I was able to keep that stamping legible, given how shallow a stamp it truly is!
When reassembling this stove, care must be taken, especially with new paint. The frame rests on a raised boss surrounding the valve threads on the tank. Just like on removal, this frame will be moving back & forth and all around when re-installing the valve, so the first thing I did was to cut out a small piece of wax paper. I cut a hole slightly larger than the valve thread diameter, and then cut a slit from the hole to the edge of the paper. I laid this down on the top of the tank.
Now, we place the frame atop the tank, lining up the holes in the frame, wax paper & tank.
A little Permatex #2 on the valve threads...
...and in she goes!
Turn the valve in counting exactly the same number of turns as you did when you removed it earlier.
Now, ease the wax paper out from under the frame. The slit that you cut will allow it to come out from around the valve.
Tighten the locknut to secure the frame to the tank.
Now, I install the valve stem & packing.
Engage the packing nut threads carefully, and screw it in finger tight.
Now, snug down the packing nut with a wrench, turning the valve knob back & forth as you go to see that the valve shaft is not getting hard to turn.
Unfortunately, in the case of this stove, this packing leaked like a sieve when pumping up pressure, no matter how much I tightened it down. Time for a new packing. Since that procedure is well covered in our forum, I didn't include it here!
The air stem is now screwed into the check valve...
...and the pump is installed & the cap screwed down.
I then place the filler plug & gasket on the fill...
...screw the cap down tight...
...attach the retainer chain and screw, then tighten well.
Now, attach the chain to the clip and secure it around the bottom of the valve.
Screw the burner head to the vaporizer.
Assembly is complete!
Here she is immediately after lighting. Valve 1/4 turn open.
About one minute later. Valve fully open.
The flame is so clean, it's almost invisible! To test it, I boiled just under 1 quart of cold water to a rolling boil in 5 minutes flat!
Here is the flame turned down to a simmering level.
Well, that's it! Hope you enjoyed!