1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Coleman Apex

Discussion in 'Other Models' started by presscall, Dec 23, 2011.

  1. presscall

    presscall United Kingdom Subscriber

    Offline
    Joined:
    Aug 25, 2009
    Messages:
    6,434
    Location:
    UK
    Early model Apex (1995), dismantled for servicing

    1324643208-1.JPG


    The valve block pricker eccentric spindle is the rod projecting at the right and an 'O'-ring provides the seal. It was sound and a dab of silicon grease ensures smooth operation

    1324643237-2.JPG


    The 'O'-ring providing the inlet flexi-hose connector seal appears to be a weak link with these stoves, judging by CCS member feedback.

    No problem when the seal is new, but it soon degrades because too much is expected of it, with the insertion and removal of the fuel tube each firing. Two 'O'-rings should be better I reasoned

    1324643251-3.JPG 1324643280-4.JPG 1324643305-5.JPG

    The extra bulk of two 'O'-rings leaves the retaining nut standing proud, but tightening it between finger and thumb when the flexi-hose fuel spigot is inserted compressed the rings and makes the seal more secure

    1324643330-6.JPG 1324643346-7.JPG


    The other issue I have with the stove is the 'O'-ring seal on the stove pump to stove bottle joint.

    On the left is a new one out of the spares kit; centre is one that's been in use for a short while; right is one that's been in use for some time

    1324643522-14.JPG

    That yellow latex skin on the 'O'-ring easily rubs off ...

    1324643543-15.JPG


    ... and can all too easily end up in the pump

    1324643389-8.JPG

    A speck in the fuel pick-up elbow blocking the pin hole venturi (it contributes to atomisation of the fuel for the Coleman easy-starting capability) would have prevented operation

    1324643405-9.JPG


    Solution to the self-destructing 'O'-rings, a more substantial item from my stock

    1324643568-16.JPG


    Flexi-hose fuel outlet tube protection sleeve, has a useful parking space on the pump to get it out of the way of the burner heat when the stove's in use

    1324643426-10.JPG 1324643449-11.JPG 1324643489-12.JPG 1324643506-13.JPG


    Reassembled, and confident there'd be no fuel leaks, stove fired up

    1324643587-17.JPG

    1324643611-18.JPG


    A characteristic of the stove seems to be a 'chugging' sound in use.

    It is I think due to the fact that unlike the more orthodox Coleman stove without a remote fuel source, the arrangement at the pump of the inlet tube above the surface of the fuel and a pinhole opening for fuel at the plastic 'elbow' joint in the fuel allows for no manual switch-over to neat fuel when the stove's warmed up.

    So it's a lean enough fuel mixture for an easy start without flaring but is a shade too lean once the stove's got hot.

    Testing my hypothesis by running the stove on butane fuel (Frankies, Mods and Hybrids Forum) results in no such 'chugging'

    Coleman Apex on butane fuel


    Something I've yet to try, but the butane conversion flexi-hose can take a Primus Ominfuel pump and fuel bottle. I expect that too would eliminate the chugging phenomenon, though flare on start-up would be substantial.

    John
     
    Last edited by a moderator: Jul 2, 2015
  2. idahostoveguy

    idahostoveguy Subscriber

    Offline
    Joined:
    Jun 15, 2009
    Messages:
    3,352
    Location:
    Potato Country USA
    Hi John,

    Beautiful tear down and presentation. Thirty-some-odd parts is quite the number.

    What I've found on these stoves after replacing generators, jets, O-rings, etc., I found that by only slightly opening the fuel valve on the pump, the chuffing stopped. It must be getting too much fuel to vaporize, or over-pressurized, or something akin to that. Opening the valve, say, 1/16 turn or less seems to stop the chuffing. I have three of these and it does it on all three. Age of the stove maybe? Worn main fuel valve? Cold weather? Still guessing.


    sam
     
  3. mr optimus

    mr optimus United Kingdom Subscriber

    Offline
    Joined:
    Oct 4, 2007
    Messages:
    2,187
    Location:
    Harlow Essex
    Hi John brilliant documented break down and service of the early Apex,i wonder waht purpose the latex skin on the pump O'ring serves,in my opinion it is a hinderance as once it breaks down as you pointed out if it does find its way into the pump and gets into the fuel pick up then theres a problem with easy starting
     
  4. toonsgt

    Offline
    Joined:
    Oct 23, 2005
    Messages:
    934
    The chuffing is caused by too open a path for fuel to return to the bottle when it hits the hot generator. Closing the valve as stated slows the fuel rate both ways and smooths things out. If you put your ear to the fuel bottle while it's running(don't burn your hair), You hear a ball check(?) clicking in sync with the chuffing. It's the cost of the simple operation design of the pinhole vs relatively huge air tube and chuffing on a full open valve nearly always happens on mine. These stoves rely on back pressure to shut off the atomization/instant light feature. When cold the volume going through the fuel tube is quite substantial and pulls air down the tube. Once warmed up, the flow reduces dramatically and the pinhole can then NEARLY keep up on it's own. When it can't, it chugs.

    Thats my take on it.

    Mike
     
  5. idahostoveguy

    idahostoveguy Subscriber

    Offline
    Joined:
    Jun 15, 2009
    Messages:
    3,352
    Location:
    Potato Country USA
    Very good take on it Mike. I'm figuring that you are right. The fuel tube is relatively large and has nothing inside of it like MSR stoves' cleaning cable. I've had occasion where my MSR stoves chuff when I don't have the cleaning cable inserted (maybe during cold weather?). Perhaps if there was something inserted into the Coleman tube to take up most of the space, the chuffing would not occur. An experiment waiting to happen...

    sam
     
  6. Murph

    Murph United States Subscriber

    Offline
    Joined:
    May 14, 2010
    Messages:
    1,670
    The yellow coating is to show that the rings are Viton, and NOT neoprene, helps in industrial settings to tell them apart in shops where both are used.

    Murph
     
  7. idahostoveguy

    idahostoveguy Subscriber

    Offline
    Joined:
    Jun 15, 2009
    Messages:
    3,352
    Location:
    Potato Country USA
    They also do Viton in brown too.



    sam
     
  8. Big BTU

    Big BTU United States Subscriber

    Offline
    Joined:
    Jan 21, 2010
    Messages:
    868
    Location:
    Hawaii
    Wow John,

    I thought I liked taking things apart! LOL. Great job as always.
     
  9. presscall

    presscall United Kingdom Subscriber

    Offline
    Joined:
    Aug 25, 2009
    Messages:
    6,434
    Location:
    UK
    I think the 'easy start' capability would be lost, and I expect that it's to facilitate that that the fuel hose is so short. Any longer and the atomised fuel would condense and flare and mess up the easy-starting capability.

    Mike's explanation for the 'chuffing' sounds good to me. I can visualise that tube to the pump/stove outlet having a succession of air bubbles in the liquid fuel, just as the pickup tube in an aerosol can does.

    To check out the stove on a wholly liquid feed I connected a Primus pump and fuel bottle to the pre-heated stove. Result was a steady, powerful flame with no 'chuffing'

    1324912600-19.JPG

    John
     
    Last edited by a moderator: Jun 26, 2015
  10. weasel Canada

    Offline
    Joined:
    Mar 15, 2010
    Messages:
    308
    Wow am I glad I found this. Just bought one today and am planning a teardown. Need to find me some o-rings. I have a couple, but will have to check for size.
     
  11. blue_ranger

    Offline
    Joined:
    Jul 11, 2012
    Messages:
    1
    Excellent write up, thank you for sharing.

    I've got one of these I bought new in '98. I tested it recently and found the pump assembly leaks when I turn the fuel valve on. My guess is that the o-ring needs to be replaced. Any thoughts on where I can find a new one? My local Ace doesn't have anything that small, and a replacement was not included in the service kit.

    Thanks!
     
  12. bajabum

    bajabum United States R.I.P. Subscriber

    Offline
    Joined:
    Dec 23, 2005
    Messages:
    7,365
    Location:
    California Coast
    Try your local Harbor Freight, they have Nitrile AND Viton O ring sets, pretty cheap...
     
  13. skorpiius Canada

    Offline
    Joined:
    Sep 28, 2013
    Messages:
    33
    I'm curious if anyone who has used or uses both the Apex I/II and the 550 could give a comparison. I had the idea that the Apex might be better because you could fully windscreen it without worrying about overheating an integrated fuel tank, but after using the 550 this weekend the add on burner-only windscreen was completely fine in 50km/hr winds, and probably wasn't even needed as the burner of both models has great built in wind screening. Thoughts?
     

Share This Page