My Coleman - (I think it's a 249 Scout) needs the NRV fixing. But it is a very different arrangement than most of my other brands. Can anyone explain how it functions please. There is a long square section rod with a taper at the inner end. Whatever is down in there is Very very tight. What gives?
The Coleman NRV (check valve) operates in a completely different way to the “Primus-type” NRVs. Its only moving part is a ball bearing that seals by force of pressure in the tank. The “rod” you refer to adds an additional seal when screwed fully clockwise into the check valve. Removal of the check valve requires a special tool, and in almost all cases its removal is not required. To service the check valve unscrew the rod and remove. Rattle the tank and see if the ball bearing moves. If not poke it with a wire, squirt some engine cleaner or acetone down the pump tube; soak the check valve that way for a couple of hours; empty; drop some penetrating oil down the middle of the check valve, and that should see it operating properly. Cheers Tony
Well, this uncooperative Scout. I've swilled out the fount dozens of times and am still getting black crap out every time -see pic. I'm not game to try any harder to unscrew the vaporiser from the fount - it just feels like it might tear out the fount it's so tight. (With other machinery I might use 'the heat spanner' but I'm dubious about potentially burning any seals down in there). Maybe I should soak it for a few days to try to clean it out, but what should I use? So far I've hit it with Kero, meths, acetone. I wonder if paint thinners would be worth a try - though it might ruin seals (?). I can't hear a ball rattling in the NRV. Poked at it with fine 'piano-wire' and used acetone down there, but no rattling sound so far. The check valve has a large screwdriver slot in it, wouldn't that remove it? -What's the special tool like?
Cleaning the fount: Is the black stuff rust or some other residue? If other residue, use old kero to rinse, rinse, and rinse again. If rust, use steel ball bearings in old kero, rattle, shake, rattle, shake etc; or soak in citric acid, then do the above; or use Evapo-Rust, then keep running until all residue is gone. The fuel control block: Don’t take off unless you need to. Can you blow air easily into the tank through the control block? If so, it should be fine. The check valve tool: It is a specialist tool. Trying to use a large screwdriver usually ends in tears. As I said before, you usually don’t need to remove it. I would soak the pump tube with penetrating oil for a day and poke the bearing again. Then I would test it by pumping air into the tank… Edit: The tool. Here is one version. The central long bolt screws into centre of the check valve; the screwdriver teeth fit the slot in the check valve, and the wing nut locks the driver to the check valve. A large spanner is then used to persuade said check valve out of its seat. Tony
Tony it's not rust, more like carbon deposits. I keep swilling with Kero, and the black stuff keeps coming out. Yes LOTS of rinsing out done. I was thinking maybe some more aggressive chemical might help to clean the inside of the fount. I'll try CRC down the NRV hole overnight, see if that helps. Does anyone ever use 'Universal' paint thinners? Cheers, -I'll keep at it.
Paint thinner on the check valve is often used. Get yourself some Penetrene. It’s the best penetrating oil around. Tony
Sectioned Coleman check valve. Here’s that removal tool in use on a Coleman stove fuel tank - identical valve to that in the lanterns. John
A pretty aggressive chemical that is also quite often used by guys like us in such tasks would be caustic lye. If you have access to it, that'd be another option you can take. If so, make a concentrated solution of lye. As it is caustic, be extra careful if you decide to give that a try. Wear protective gear. It'd 'eat' most organic matter including old fuel residues, leather, many paints, some rubbers, grease, fats, oils, skin, hair and certainly some of your flesh if you're not careful. It doesn't appeciably attack the metal of the lantern unless there is aluminium or other reactive metals in the construction. (There aren't any on a 249). Since yours isn't painted, there isn't any real risk of damage on the lantern. Remove the filler cap/gasket, pour the lye solution in, place the filled fount inside a protective air-tight plastic container and let soak for a day. The rubber gasket is about the only part that might be attacked by the lye. Lye does not attack rust and not good for derusting unless its done in an electrolytic bath. Carefully swirl the liquid around a couple of times to wet the entire inner surface of the fount. Be careful that it doesn't spill onto your skin. If you have enough lye solution, you can even immerse the entire fount(without the filler cap) in it and let it do its job. Pour the stuff out the next day and you should get most of the unwanted crud out of the fount. Rinse, flush, shake with water with some steel ball bearings, bolts or nuts to remove the last remaining bits.(most of the black crud would be much loosened after the lye soak). You can finish off with denatured alcohol, paint thinners or acetone if necessary. The final rinse should preferably be done using the fuel itself(kerosene). You can also apply the lye solution in the pump tube and check valve if its still not clearing up with acetone. I'd not remove the check valve with a screwdriver. Doing that usually results in deformation or destruction of the check valve's slotted end.
The checkvalveremovaltool from oldcolemanparts.com works a charm. Expensive, but keeps frustration away.
Caustic soda crystals from the supermarket, should work, warm water too, but keep it moving , swilling around etc , don't let it settle ....
John's (presscall) pictures are truly worth a thousand words. The Coleman check valve (CV) requires both parts, the CV and the air stem (the rod with the threaded point). The CV is only intended to retard air coming out of the fount enough for you to pump up[ the fount. The true air tight seal is the end of the air stem against the CV. Check the point on the air stem, often they have been over tightened by a previous owner and have a groove cut around the face where it contacts the CV. If it's grooved you may want to either polish out the groove or replace the air stem. The crudest but easiest way to check the CV function is to remove everything except the CV from the pump tube, clean the fuel fill opening then with the fuel valve closed, make a seal with you lips around the fuel fill port a nf blow air into the fount. If the CV is leaking excessively you'll hear the air escaping up the pump tube. If the CV is working you will hear little to nothing. The key to the tool is the rod that holds the tool tightly in the slot of the CV. An ordinary screwdriver with a wedge (seen from the side) shaped blade will climb out of even ordinary screw slots. Even a hollow grod blade with parallel side is difficult to hold in place. The CV is rather soft brass and the slot is easily damaged. Once you've buggered the slot it gets really ugly quickly and things like drills, screw extractors, impact wrenches levers, cranes, excavators and even small amounts of explosives get called into play, usually with dismal results. From the inventor of the CV tools, the proper way to use it is to attach it to the CV then put the wrench on and give the free end of the wrench a smart whack with a suitable implement. I use a 1 pound rubber mallet. The sudden impact does a better job of breaking the CV free without damage to the pump tube than does slow steady pressure. It also saves your knuckles with the CV suddenly breaks loose and your hand slams into the benchtop.
