To get a stuck Shraeder valve core regardless if its broken or not out of a Coleman 400 brass F/A tube use heat! The pic above shows the exploded Valve Assembly for the 400 (on Top) and the 400B (on Bottom). At top left you can see the original 400 valve core broken in 2 parts. The left piece is the crimped on top-section with the threads. The right piece is the bottom-section that was "hopelessly stuck" in the Full-Brass F/A Tube. The valve core has 2 sections that are crimped together. The top-section has the threads to screw into place and the bottom-section does the actual pressure sealing. When unscrewing a stuck valve-core it takes surprisingly little torque to easily tear the top-section of the crimp off leaving the bottom-section hopelessly stuck in the brass F/A tube. I believe the seal material used back then would have been NBR or nitrile, which is good with petroleum fuels but it has a somewhat lower upper temperature limit around 250 degrees. Melted NBR is the culprit responsible for locking the bottom-section of the valve core so tight that it won't budge and is apparently stronger than the shear strength of the crimp. Removal of the stuck bottom-section is easy with 20-30 seconds of torch heat on the brass F/A Tube and then pull the exposed schraeder stem out with a needle nose to easily extract it. Effortless! The next problem is to find the correct replacement which is easier said than done. Tire schraeder valves are not rated for petroleum fuels. Schraeder valve-cores with Viton (FKM) seals seems the only option. No more Nitrile! My original Coleman valve-core total stem length was 0.080! LENGTH IS CRITICAL for max fuel draw only achieved at max extension of the F/A Tube inner rod via the length of the valve core stem! Here is my discovery so far: Napa 209578 NOT VITON I heard about this and got one. I just discovered its a refrigerant seal and NOT VITON! AC Delco 88894338 YES VITON Acceptable because its for a Fuel Injector Rail. Waiting for it to arrive to measure its length. If anyone has any relevant valve-core mfg & part numbers or any other info to add please send it along!!! More to come. Ron
I've replaced a couple of these on 400 and 400A stoves. I had over 100 of the Viton valve cores and sent a bunch to Old Coleman Parts. If they aren't currently posted at the online store yet, email Rob over there and you should be able to buy one.
@SKLColorado OMG! I have seen a number of your blog entries on some blog somewhere. I feel I should know exactly which but I don't. It came up when I did a search and I clicked on "it". Anyway, I absolutely loved your blogs. In fact, I learned a huge amount from you and am still incredibly inspired by you and your work! Your stove blogs are fantastic!!! I loved the ones on the 400 stove, but I was also completely blown away by your Optimus 323 blog! Great job!!! I would have left you feedback many times but it required some sort of login to something (Wordpress?) and I am sick of all these logins so I didn't. So, I am excited I get the chance to tell you now! I don't recall you ever saying HEAT was the necessary "trick" to easily remove a stuck valve-core, though you may well have and I missed it via a sloppy, quick read-thru. It would not be the 1st time I missed info! I did search Old Coleman Parts clicking the "Stoves" link trails for both the 400A and the 400B. There was no link for the 400 stove. The limited parts available do not include a schraeder valve for either of them. But for Lantens/275 I did find a schraeder. So I am aware they have at least one version. Its orange. I hope that means VITON. I will definitely email Rob! Thanks for the tip! I am currently waiting AC Delco viton schraeder to arrive. It may work. Who knows. I need to measure it and install it. The total length of the actual valve-core-stem is critical. It must be long enough to push the inner rod of the 400 brass F/A tube down far enough to allow for max fuel flow. That stem sticks out from the top and the bottom. So I think of the 3 length: total length of the stem, the top half length and the bottom half length. The red-knob valve-assembly on the 400 activates nothing on the top end of the valve but on the bottom end it opens the valve core which in turn pushes down the inner rod. But it must push the rod down low enough to get max fuel flow. The eccentric only does work by going downward to allow fuel. Upward is to close the fuel by undoing what it did when it went downward. The 400B on the other hand with the plastic F/A Tube is different. The red-knob valve-assembly on the 400B uses the eccentric to do work by going upward to activate the cleaning wire through the generator on the top end of the valve. And it does work in the downward direction similrly to the 400 as it opens the valve core only BUT nothing more. So the silver valve-core stem doesn't need as much length on its bottom side. However it does need a certain amount of stem length on the top to get engaged by the eccentric. These inner valve-core stem lengths would be of no importance to me if Coleman produced exact "factory" replacements for us for the 400 et al, but they don't. And when you get into the wide world of after market schraeder valves a small difference in stem length may well impact the performance of the stove. There is no guarantee there is one standard length. In fact, the Napa valve I replaced in my 400 DOES not push the inner rod down far enough. So its shorter. I believe the original Coleman valve-core used for the 400B doesn't have to be the same length as the original Coleman valve-core used for the 400. But they probably were the same. Easier to produce just one for all the 400 stoves. Probably beyond the 400's. I don't know. Merely conjecture. At this time I have not yet taken apart a 400A valve assembly and F/A tube so I don't know 1st hand if its plastic or brass. I'll get there soon enough. I have other stoves I am doing first. One last question that maybe you know the answer to. Do you have a source for the extremely thin, flat, black, maleable seal used on the plastic F/A Tube where it is screwed into the red-knob valve? It sure doesn't appear to be an o-ring squished flat. OCP sells an O-ring replacement. But the original flat "washer" on the plastic F/A Tube is a rather elegant solution. Ron
Thanks @SKLColorado I emailed OCP and am waiting to hear back! Great news! The AC Delco 88894338 VITON valve-core for a GM Fuel Injector Rail that I ordered arrived. Its actully a little longer at 0.089. The original Coleman valve-core-stem length was 0.080 for the Coleman 400-499 Brown stove with the brass F/A Tube. The total length of the actual valve-core-stem is critical. It must be long enough to push the inner rod of the brass F/A tube down far enough to allow for max fuel flow. I need to install it and put the stove together to test it. If necessary I can always file off the teensiest amount. AC Delco 88894338 is VITON and is long enough. Its built like a tank - way more solid than any other valve core I've ever seen. Probably because its for an automotive Fuel Injector Rail pressure relief valve. The only down side is cost: $7.19 each. But its worth it if a correct replacement can't be found anywhere else!
