Petromax 829 burns like the waves?

Discussion in 'Fettling Forum' started by Bram van Houten, Feb 25, 2019.

  1. Bram van Houten

    May 1, 2018
    I've restored an old 829 bundeswehr last year. In november it started losing pressure over short time (15 minutes or so), I've just solved that problem by retightening the nuts at the pre-heater. I needed to keep the lighter on with the pre-heater to keep it going (never needed to do this before) and after 90 sec I could light the lamp.

    There is one thing that annoys me besides the pre-heater not being abled to burn on it's own. The lamp is now burning in short bursts, it sounds like waves on the sea actually. So it's burning but with waves it burns a little harder than lower and then harder again. With 2 - 3 second intervalls. What could be the problem?

    Thanks in advance, excuses for my rubbish english (I'm dutch, and it's late :p)

    JEFF JOHNSON United Kingdom Subscriber

    Nov 28, 2010
    Shetland Islands UK..
    Your lantern is pulsing and that can be caused by a variety of problems, muck on the pricker rod, loose ceramic nozzle, slightly loose jet, the air gap on the burner may need adjusting, muck in the tank.
    Do let us know how you get on.
  3. WimVe

    WimVe Subscriber

    Aug 3, 2011

    Although maybe not related I think that both issues may have to do with dirt in the feeding tubes.
    Make sure the small filter, feed pipe and air holes of the rapid are clean and open.

    Check if the pressure is OK.
    The indicator on the filler cap is known as being that: an indicator but you can check it with a "lighter gas" can (aansteker gasbus).
    They operate at 2 bar, so putting it on the indicator should result in 2 bar.

    Besides this all: a slight pulsing is normal due to the "leidenfrost" effect > pressure change due to vaporizing of the fuel.

    Have fun !
  4. MYN

    Feb 28, 2018
    So @Bram van Houten ,
    Are you burning petrol(benzin) in your Bundeswehr 829, which I'm guessing, has a straight vaporizer? Or its been converted to burn kerosene with the Preston loop vaporiser?
    Either ways, just check (with the inner burner hood removed) that the jet is shooting a sharp fine fuel upwards when you pressurize the fount and turn down the pricker. See if its a continuous/uniform stream of fuel or sometimes spurting erratically. If its a uniform fuel stream, then the pulsing might be due to an exagerated 'Leidenfrost' effect during burning.
    If the fuel stream is erratic, then normally its due to dirt, carbon or leakage somewhere on the vaporiser or jet.
    Both can be solved.

Share This Page