Project 520

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BobA
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Project 520

#1

Post by BobA »

Glad you could join me once again for yet another installment of restoration tutorials.
This one is called...

Project 520

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:


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Let's get started. We first unscrew the burner head from the vaporizer...


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then lift it out.


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Unscrew the jamb nut...



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and remove it.


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Carefully lift the vaporizer up and off, being careful not to damage the cleaning rod & needle.


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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.

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Now, I loosened and unscrewed the packing nut...



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and removed the valve stem.


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Next, I removed the pump cap, and lifted out the pump.


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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.


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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:


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Had to remove the chain that retains the fuel cap.

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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!


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Lift out the valve.


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And, finally, the frame!


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Next problem. I'll bet that you think that this is a pretty nice looking tank:


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Well, here are a couple of other shots:


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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.


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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:


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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!


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Carefully lowering the vaporizer back into place, so as not to destroy the cleaning needle!


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Installing the jamb nut.


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Some photos of the cleaned & polished burner head...


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and the frame.


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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...


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You can even still see the (unbelievably lightly stamped) I.D. stamp...

U.S.
1943

Coleman

...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.


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Now, we place the frame atop the tank, lining up the holes in the frame, wax paper & tank.


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A little Permatex #2 on the valve threads...


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...and in she goes!


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Turn the valve in counting exactly the same number of turns as you did when you removed it earlier.


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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.


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Tighten the locknut to secure the frame to the tank.


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Now, I install the valve stem & packing.


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Engage the packing nut threads carefully, and screw it in finger tight.


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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.


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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...


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...and the pump is installed & the cap screwed down.


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I then place the filler plug & gasket on the fill...


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...screw the cap down tight...


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...attach the retainer chain and screw, then tighten well.


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Now, attach the chain to the clip and secure it around the bottom of the valve.


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Screw the burner head to the vaporizer.


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Assembly is complete!


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Here she is immediately after lighting. Valve 1/4 turn open.


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About one minute later. Valve fully open.


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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.


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Well, that's it! Hope you enjoyed!


BobA

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Trout
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Project 520

#2

Post by Trout »

Another SUPER job there Bob. Thank you, I didn't have to take mine that far down but if I ever do I know where to come!

Clap, clap, clap, clap, clap, clap, clap, clap, clap, clap, clap, clap, clap,clap, clap, clap, clap, clap, clap.......
Mike
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SteveRetherford
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Project 520

#3

Post by SteveRetherford »

nice pictorial !!! but you dont have to take off the fuel cap chain clip that way , just leave it in place on removal . make sure to put it over the fuel and air assembly before you re instal the valve ... did something similar once and the clip broke , so i just leave it in place for dis asembly and put in place before reasembly .
Steve , Keeper of the Light !!!
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Project 520

#4

Post by Thom »

Wonderful, thank you!
Thom
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Deanofid
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Project 520

#5

Post by Deanofid »

Excellent job and a great tutorial, Bob!
Remind me in a week or so and we will put this in the Tech Archives so it will be easy to find.
Dean -Midnight Kerosene Ritualist--Deans Machine:  Deansmachine.com  
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BobA
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Project 520

#6

Post by BobA »

SteveRetherford wrote: nice pictorial !!! but you dont have to take off the fuel cap chain clip that way ,

You're absolutely right, Steve. Y'know why I did that? If you'll notice, on disassembly, I used a thick Craftsman 9/16" wrench. The clip was completely in my way. The thing is, I didn't remember until later that I have a Coleman Universal Wrench, which would've allowed me to loosen that nut easily, with the clip in place.

Senility is a terrible thing! [confused]


BobA


BobA
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Project 520

#7

Post by BobA »

HRidarick wrote: The tank cleaned up great...good to see it being put to use!

It sure did, Hoddy! Especially the inside. I couldn't believe how great the inside of that tank looked once I got the crud out of it (and, boy, was there a ton of it!). It looked virtually like a new tank. Gave it the POR-15 treatment just in case there was a bad spot or two where I couldn't see. But, overall, I am extremely happy with how the tank (the entire stove actually) came out.

Thanks again...


BobA
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Project 520

#8

Post by BobA »

deanofid wrote: Excellent job and a great tutorial, Bob!
Remind me in a week or so and we will put this in the Tech Archives so it will be easy to find.

Will do, Dean - and, thank you!


BobA

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Gavercronos
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Project 520

#9

Post by Gavercronos »

Great job- question about the fuel cap:
Is that the normal size cap or the small one like on the 242s? If the latter, how common are they? (My 1943 520 has a normal size cap.)
WillCat

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BobA
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Project 520

#10

Post by BobA »

Gavercronos wrote: Great job- question about the fuel cap:
Is that the normal size cap or the small one like on the 242s? If the latter, how common are they? (My 1943 520 has a normal size cap.)

Thanks Bill!

About the fuel cap - mine is the smaller 242-style cap! From what I understand, they changed to the "regular" cap sometime in 1943. My stove is the early design all the way around. It has the small fuel cap, no preheat cup, no place to hold the wrench, and uses the early one-piece utility cup/cover.

From what I've read, they used the small cap from 1941 to mid-1943, and the regular cap from mid-1943 to 1945. Who knows if it's truly that simple?


BobA
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#11

Post by HillCountry »

Excellent tutorial Bob! And a very nice stove also!
Tim - ICCC Member #1217
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#12

Post by Bob1774 »

Wow! Great job.
Thanks Bob, and Dean for putting this in the archives. I have the '42, four leg 520, and will certainly refer to this if I decide to do a tear down.
Also, thanks for the comment on the wrench. Mine has the small fuel cap and unchained funnel, and I always wondered how the wrench was attached. Glad to know that the funnel and wrench were evidently loose on these early stoves. Not a great idea for field use, but they fixed that in short order.
Again, nice tutorial and documentation.
Bob
BobA
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Project 520

#13

Post by BobA »

Bob1774 wrote: Wow! Great job.
Thanks Bob, and Dean for putting this in the archives. I have the '42, four leg 520, and will certainly refer to this if I decide to do a tear down.
Also, thanks for the comment on the wrench. Mine has the small fuel cap and unchained funnel, and I always wondered how the wrench was attached. Glad to know that the funnel and wrench were evidently loose on these early stoves. Not a great idea for field use, but they fixed that in short order.
Again, nice tutorial and documentation.

Hi Bob,

You have the early wrench & unchained funnel? Is there any way that you can post some photos of these? My stove came with neither, and I haven't been able to find any photos of these items. I'll be looking for these, and it'd be nice to know exactly what they look like!

Thanks,

BobA
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#14

Post by Bob1774 »

Bob,
Below are a couple of photos.
I was lucky to get this stove in the original box, with original instructions and all the spare parts, including the pump cup and cap seal. My parts "tube," was the larger one with the spare generator and three screens, graphite packing, and pricker. Quite a complete deal. Noticed the wrench is not pictured, but you can see them on Mike's site here for sale.
The instruction sheet mentions you can purchase the funnel, and that the "utility cups," come in one or two piece, like the later standard 530's have. Mine has the single snap on cover/cup.
Let me know if need a scan of the instruction sheet.

Bob
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#15

Post by curlyjoe_99 »

wow and awesome resto. [sSig_youtheman]
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#16

Post by JustOneMore »

Here's a pic of the wrench and parts tube from my '43 Coleman.


520-6.jpg

Great post Bob. Very helpful.

Dana
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While it is certainly nice to find what you collect, in reality you must collect what you find.
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#17

Post by Majicwrench »

Question, in the picture of Bob's, above the picture with the Big Flame, the support to the right of the fuel cap has a thingy sticking out, what is that for??

I got one of these this weekend, it has the small fill cap and a loose funnel, and a nice set of instruction!! But what is that thingy for??
Keith
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#18

Post by ThosKiwi »

What a great tutorial Bob!
Congratulations on a job well done!
Now I want to find a Toronto one....
Cheers
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#19

Post by HillCountry »

That is a spring that holds the can on as a cover. The early ones did not have a two part canister with a top and bottom, just a can that is held in place by that spring.
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#20

Post by Majicwrench »

I always learn such good stuff from you guys.....mine just has the one long can and I figured it was missing the other half...
Thanks Tim!
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#21

Post by Bob1774 »

Keith,
Look at the parts list in your instruction sheet,and see if they listed a "two part utility cup," as an option? My '42 instruction sheet did. Also, those loose funnels are pretty scarce, so great score!
Bob
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#22

Post by BobA »

First, thanks to everyone for the kind words!


JustOneMore wrote: Here's a pic of the wrench and parts tube from my '43 Coleman.


520-6.jpg

Great post Bob. Very helpful.

Dana

Your stove must be the "late" '43. Apparently 1943 was the year that most of the changes & updates were made to this stove. Yours has (obviously) the large spare parts tube & the wrench (and a place on the frame to store the wrench!). Correct me if I'm wrong, but it probably also has a preheat cup, the large fuel filler cap, and the chained-on funnel. Also, probably has the 2-piece utility cup/case. It possibly might also have the orange decal on the tank:

3.jpg

Am I right (or partially right)?


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#23

Post by JustOneMore »

Bob,
You are right about the details of my stove however, I cannot confirm the label as it was removed, probably by the soldier who was using it. The 2 piece can has remnants of black paint so maybe the label was removed for "cloaking" or possibly to make it easier to get in and out of the can. Like all my warbirds I only do what is necessary to get them running. I feel fortunate to have this stove. I only wish it could speak.

Dana
If it has a flame, I like it.
While it is certainly nice to find what you collect, in reality you must collect what you find.
The Coleman Blue's 243's #009  BernzOmatic Appreciation Club #029
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#24

Post by Gavercronos »

Bob, Your description is a dead ringer for mine. Since this project and mine are both confirmed 1943s, I don't think we need the qualifier "Apparently". These changes all happened in 1943, likely very quickly, possibly all at once. Makes me curious if there are some out there with a mix of early and late features...
WillCat

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BobA
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#25

Post by BobA »

Hi Bill,

I used the term "apparently" because I don't consider myself an expert on these stoves. I'm still learning more about them as I go on. In the past, I have believed myself to be expert in a given matter or item, only to be proven wrong publicly by some new information which was brought forth. [sEm_oops2] [sEm_blush8]

So, I quickly learned that qualifiers were my friends! [absolutely]

Makes me curious if there are some out there with a mix of early and late features...
...that came from the factory that way - rather than something some later owner cobbled together!

Indeed. I've wondered about this, as well.


BobA

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