Coleman 501A generator cleaning?

Discussion in 'Fettling Forum' started by New London Mike, Oct 23, 2021.

  1. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    I bought one of these 501A stove off ebay about 10 years ago. From what I'm able to tell, since the shutoff valve is upstream from the generator, the serious issue of the 501 stove is essentially ameliorated. I spent a fair amount of time with it and now my stove runs ok, but it needs either a new generator (ha ha) or the generator itself needs a good cleaning. Does anyone know how to do that? Also, I could use a manual for this stove. Are these available anywhere? Thanks to all, Mike.
     
  2. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

    Offline
    Joined:
    Aug 25, 2009
    Messages:
    10,961
    Location:
    Lancashire, United Kingdom
    @New London Mike By ‘manual’ maybe you mean operating instructions or perhaps something more comprehensive? I don’t know of a ready source for either. The stove had a short production run, so the stove and even more so an instruction sheet, are thin on the ground.

    HERE’s my report on my 501A, which you may find helpful.

    Disassembled.

    5F27318F-6C79-4BC7-A79A-03CC7615B01B.jpeg


    The 501A generator is on the left. That for a 501 is on the right.

    EC819CA4-7AF4-4065-9BD4-484E0771F813.jpeg


    Neither has a pricker wire inside - there’s a separate pricker arrangement as I illustrate in my write-up - so de-coking is possible. I’d do that by removing the generator, placing it on a fire-proof surface and playing a gentle flame from a blowtorch over it, getting it red hot but barely, and well short of melting the brass tubing. A gentle flame as I say, and move it around, not letting it linger in any one spot. Let the generator cool, tap it gently throughout its length with a screwdriver blade and tip the debris dislodged out. An air line would be very useful to pop a blast of air through it.

    Coleman fuel only and not pump gas and there shouldn’t be any coking of a generator.

    John
     
  3. Majicwrench

    Majicwrench Subscriber

    Offline
    Joined:
    Jun 21, 2012
    Messages:
    1,443
    What is the stove doing that makes you think it needs a generator?
     
  4. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    First, thanks, John, for the very comprehensive reply. I'm not really sure what a "pricker wire" is, but I'm guessing it's the long very thin rod that goes through the generator on, e.g., a Coleman 425, that has a needle on the end for cleaning out the jet. If so, I can see why these circular generators don't have "pricker wires", due to the shape. Now, to Majicwrench's question...I think my generator is clogged because I get a flame, but it's weak (not of the intensity I've come to expect from other Coleman stoves). In addition, when I try blowing compressed air through the (disassembled) generator I can barely get any through. I think I'm going to try to hook up my compressed air source to one end of the generator, set the pressure to 100 PSI or so and then try John's suggestion of heating the generator (carefully) with my acetylene-air torch. Maybe the combination of the air pressure plus the heat will combust the crud inside and clear it out.
     
  5. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

    Offline
    Joined:
    Aug 25, 2009
    Messages:
    10,961
    Location:
    Lancashire, United Kingdom
    @New London Mike Yes to your understanding of ‘pricker wire’.

    Easy as you go on your method for cleaning. Compressed air and a torch flame at the same time could create an intense amount of heat in the generator. Old Coleman Parts (USA) might have a spare generator.
     
  6. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    Yep; good point. I'll have to make sure I don't end up with a blob of brass on my basement floor. As for Old Coleman Parts, I tried them already. No dice.

    One other thing. Does anyone know of a special wrench that's used to remove the check valve at the bottom of the pump cylinder. I fashioned something out of a piece of steel and a 6 point 9/16" socket but it doesn't seem to be gripping this time around and I'm wary of damaging the check valve.
     
  7. Fettler United States

    Offline
    Joined:
    Mar 9, 2019
    Messages:
    284
    Location:
    Ioway
    Would that type generator have enough clearance to allow passage of anything?

    I'm thinking out loud here - take say an old phosphor wound guitar string, should be stiff enough yet flexible enough to slide through, and then run it back and forth like dental floss.

    Check Valve - I'd try really thorough cleaning and flushing first before yanking that thing. They usually respond pretty well to that.
     
  8. cottage hill bill

    cottage hill bill Subscriber

    Offline
    Joined:
    Jan 8, 2011
    Messages:
    1,207
    Yes there is a special tool for removing Coleman check valves. Well worth having if you rehab more than one GPA. However, the check valves rarely go bad and cleaning should be sufficient. Use the straw on a can of WD40 and squirt a little bit into the CV. Use a bamboo skewer or other bit of long thin wood to poke into the hole and massage the ball in the CV a bit. Pour in a bit more Coleman fuel into the pump tube (just a couple teaspoons full) and use the pump to push that through the CV. You can check the CV operation by making sure the tank is empty, the fuel port is clean then with the pump out blow into the tank like you're blowing up a balloon. You should not hear a lot of air coming out of the CV and there should be resistance to blowing up the tank.

    In my experience 100 psi is way too much pressure. To decoke the generator you only want a 2-3 psi, just enough to add some oxygen to the heat. 100 psi may very well act to cool the generator, or as John suggests, create a thermal lance with unhappy results.

    Do not be complacent that the bad design of the 501 was fixed with the 501a. Both models were recalled by Coleman with instructions to Coleman service centers that if a customer came in with either for repair the stove was to be confiscated and the customer given a new 502 free of charge.
     
  9. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    Thanks everyone for all the helpful information. I performed the test that Bill describes above and it appears as if my CV is operating just fine.

    As for Fettler's suggestion about using an old guitar string to run in and out of the generator, that's a great idea. I'm going to look around my shop for some reasonable facsimile thereof. I'm a little reluctant to steel a string from my wife's guitar.

    I am somewhat concerned by Bill's comment above "Do not be complacent that the bad design of the 501 was fixed with the 501a.". What, specifically, can go wrong with the 501A?
     
  10. Fettler United States

    Offline
    Joined:
    Mar 9, 2019
    Messages:
    284
    Location:
    Ioway
    Put a fresh set on and tune it up for her. You'll get some cool points for that!
     
  11. cottage hill bill

    cottage hill bill Subscriber

    Offline
    Joined:
    Jan 8, 2011
    Messages:
    1,207
    There were two problems with the 501. The fuel shutoff was on the wrong side of the generator and the circular generator itself. The first issue was corrected with the 501a but not the second. The circular generator is prone to poor vaporization leading to flooding and flare ups. Also the cleaning lever assembly takes a while to come up to temperature and can lead to flooding and flare ups. A company like Coleman doesn't undertake a total recall and destruction of a product lightly. If you call Coleman today and ask about service on a 501 or 501a they will tell you in no uncertain terms to destroy the stove. That should be enough to give you pause about using the stove on a regular basis.

    The 502 is an excellent and safe stove with the same footprint as the 501/501a. For me it just doesn't pass a basic risk/benefit analysis to use a stove with known serious safety issues over one with a well established history of safe use.

    Most of us have a 501 or 501a or both in our collections. Mine have a sticker on the bottom explaining they are not safe to use. I will fire one up on occasion but under controlled conditions and only for a few minutes, certainly not as a daily user or a main stove on a camping trip. Some collectors go as far as permanently disabling the stove by soldering up some part of the fuel path or drilling the tank.

    I believe there is a coil in the generator which you may or may not be able to remove/reinstall that will prevent the use of the guitar string for cleaning.
     
  12. Majicwrench

    Majicwrench Subscriber

    Offline
    Joined:
    Jun 21, 2012
    Messages:
    1,443
    Most old stoves suffer from things like cap gasket leaking, which will cause really low output. I like to spray some soapy water around the cap while stove is under pressure and watch for bubbles.

    I change the cap gasket on almost every old stove/lantern I get.

    The generator only has to pass enough fuel to go through a teeny tiny hole...probably .007 or so.

    I don't have a 501, if I did have it I would use it. Maybe not in the living room.
    All stoves are potentially dangerous.
     
  13. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    Thanks everyone for the good advice. I have no intention of using this stove as a workhorse. I think once I get it working I'm going to empty it out and use it very sparingly, and only with my fire extinguisher at the ready. I have to admit, I'm somewhat baffled as to how to disassemble the cleaning lever assembly. After I take off the plastic lever, the nut and the metal barrel, does it just pull out, or is there a trick?
     
  14. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

    Offline
    Joined:
    Aug 25, 2009
    Messages:
    10,961
    Location:
    Lancashire, United Kingdom
    I didn’t describe the process in the post I provided a link to but it contained this picture sequence.

    53EA0FB9-D34D-4FFD-8D04-96BF47B67233.jpeg

    63C558F2-ED5B-4130-9882-441CAC9E7767.jpeg

    257637BC-BF81-4A30-801C-194BB5CBCE10.jpeg

    It should, yes, but the graphite packing’s probably wanting to stay put.

    There’s a coarse left-hand threaded component in there.

    6F0A1889-B1AF-4106-8AD9-1A678D3BA623.jpeg


    With the packing nut removed, re-fit the lever (or use a small wrench that fits the flats) and turn the spindle clockwise to disengage those threads and loosen the bond of the graphite packing in the valve bore.
     
  15. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    Thanks for all of the detail. So, I'm guessing that once I get this apart the graphite will fall apart in my hands. Is that what usually happens? And if so, is there a good replacement for the graphite?
     
  16. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    Oh, and maybe one other piece of information? How does the red control valve adjust the air:fuel mixture (lean vs. normal)? I'm fairly sure that mine is not operating properly because the flame will not stay lit at the 1/4 turn mark. I read something about a spring?
     
  17. Doc Mark

    Doc Mark SotM Winner Subscriber

    Offline
    Joined:
    Dec 12, 2004
    Messages:
    18,350
    Howdy, @New London Mike ,

    I STRONGLY advise you NOT to fire this stove up any more, and to use it, ONLY for the enjoyment of having a somewhat rare stove, and that's all! From what I am reading, you are, quite literally, "playing with fire" here, and to do as you wish to do, is dangerous, and, IMHO foolish! Enjoy the 501A as a dangerous dinosaur, which should NEVER be used, PERIOD! I have one that's very close to new, and I will never fire it up! My home, and my own life, are worth far more than any enjoyment I might get in playing this possibly dangerous game!! As has been mentioned, Coleman would never take recalling an entire series of stoves, lightly. THEY recommend destroying the 501 and 501A, and that should give you pause to consider the dire consequences of desiring to fire this stove up!! Get a nice 502, and enjoy it 'til the cows come home! IT is safe, the 501 stoves are NOT!! For what it's worth, I deeply hope you will reconsider the path you are currently embracing!

    Doc
     
  18. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    Hi Doc Mark, thanks for your stern warnings. I get it. It seems to me that correcting the main problem of the 501, that being the location of the fuel valve downstream from the generator, was not sufficient to make the 501A a safe stove to operate. The other issue, that others have pointed out, is that the heat transfer in the generator is quite slow until it comes up to temperature. This was probably OK when the generator was new, but as it aged and got all carboned up, the heat transfer was probably so slow that it tempted users to open the fuel valve too soon causing raw fuel to enter the burner and exit as a growling puddle of flaming destruction. I will set this stove aside with clear warnings to my heirs not to operate it due to safety issues.
     
  19. Majicwrench

    Majicwrench Subscriber

    Offline
    Joined:
    Jun 21, 2012
    Messages:
    1,443
    Well, if it got carboned up it must have been used successfully.....
     
  20. New London Mike

    New London Mike United States Subscriber

    Offline
    Joined:
    Aug 9, 2021
    Messages:
    16
    Location:
    New London, CT, USA
    Good point; I'm not sure how long it took for complaints to come into Coleman about problems with the 501A, but I'm guessing that these stoves probably worked fine when new (or else why would they have even passed internal quality control).

    Now, onto something a bit more embarrassing. I was rebuilding the cleaner-regulator assembly and accidentally over-torqued the fuel jet (aka gas tip, part 501B3181), snapping it off. I tried to buy a new 501B3181 from oldcolemanparts.com, but Mike told me that he doesn't have any. Does anyone out there know where i can get a new jet?