Greetings everyone, Received an 829/rapid that was internally varnished from who knows what it was burning. Not wanting to tear it down and rebuild it I left it intact and soaked the font internally with denatured alcohol over the course of 5 days along with bb's and agitation multiple times daily. Exchanging the alcohol daily until it was relatively clear and sediment free then checking the pressure and flow path which passed a 10 ft. high fuel stream through the jet. After flushing the system and fueling the drained font and firing up the lantern I ran into a few issues that I need some help with. The lantern when pressurized at 1.5 atms. The lantern dimly lights, pulses (hissing pressure pulses) to brightly lit and then back to dim while making a gurgling fount sound in between these cycles. This is a continuing event and one can hear the noise of bubbles within the fount when it occurs. The between the dim and bright cycles varies between 30 seconds and a minute. After 5-6 of these cycles the mantle begins to stop incandescing starting at the mantle top fading to the middle where it relights to the dim cycle and starts the process again. It seems as if there could be an intermittent obstruction of flow in the system but not sure. I do not know if it is in the fount (fuel pick-up}or elsewhere. The fount gurgling is very odd. Perhaps I should drain the font again and re-soak with alcohol again, hoping not to tear it down. Looking for some advice to solve the problem.
Hi Larry, If you turn the knob 360 degrees as it is dying out does it improve any? It sounds kinda like an eventual loss of air pressure or that there is a small obstruction in the vaporizer. If it was mine I'd tear it down and replace all the seals and pips.
Hi Larry, i have some petromax lanterns and many chinese variety clones, no matter the origin, bad seals or adjustment make for poor running quality, i agree with John, all new seals, definately give the complete vapourized a through clean inside when dismantled, then check Air gap betweenb the top of the jet to the bottom of the mixing chamber tube, i think it is 14mm, more knowledgable guys on here would know for sure, but any air leaks in the system make for headaches, see how you go, Frank
Hi, the effect that you described is commonly seen on some of the Petromaxes & their clones. It mainly has to do with the vaporizer tube: For some reason there is a retardation of boiling the fuel. At some time the fuel almost immediately starts to boil very intensely, thus giving a high fuel output to the jet (bright light), but also pushes some fuel back into the tank through the pickup tube, which causes the "bubbling" sound. Once the vaporizer tube is empty, it takes a time to "refill" it from the tank and then the process starts again. During the time the vaporizer tube is empty it happens that the fuel flow through the jet is way too low, which can even cause "backfiring" into the mixing tube. Further the tank will get very hot because of hot fuel being pushed back into it frequently. To prevent/stop this behaviour you should clean the upper & lower part of the vaporizer thoroughly, replace/maintain the vaporizer bottom valve (at the lower end of the fuel pickup), change to a "bulb"-shaped mantle with sufficient size, pressurize the lantern to the correct amount (maybe experiment with different operating pressure) and maybe even put in some brass gauze into the upper part of the vaporizer (e.g. wrapped around the pricker rod). Good luck with your "nasty" lantern, Martin
I'm no expert on these lanterns but what Martin says about lack of pressure makes sense - I've seen the very same effect on lots of other lanterns when they needed pumping. I'd ignore what the gauge says - it's probably faulty - and give the lantern a good pump-up. If that brings no improvement then try the other things suggested...
Thanks everyone for your suggestions, I resolved the tank gurgling and pulsing. After several tank flushings with K1, I was able to get a clean drain of fuel not contaminated with water and a gelatinous slime on the bottom of the separated bi-phasic layer. After refueling and a new burnt in mantle I now have the dreaded yellow flame exiting the mantle and blackening of the mantel. The flame will go out when the control knob is turned 6 o'clock. This is usually indicative of an incorrect fuel/air ratio. The gap at the jet/air tube interface is at the recommended 14.2 mm.as per measured and checked with a spanner wrench gauge. It does not appear that the foot valve is malfunctioning. The strange thing to me is that the air tube is not centered over the jet and I do not know if that is normal. The only adjustment of the air fuel tube is up or down. I did disassemble the vaporizer, removed the jet and sprayed the vaporizer with carb cleaner over night and shall soak in citric acid/water and re carb spray. The vaporizer did not seem to be occluded and appeared to be unrestricted I shall replace the jet and needle later then reassemble and see what happens. If that doesn't do it then I guess a rebuild would be appropriate. Thanks for the suggestions and feel free to anything if I missed anything. The air/fuel tube however does seem odd to me that it does not line up TDC over the jet and no way to line it up if it needs to be. Regards
The alignment of the jet to mixing tube is fixed and if the inner hood locks into the upper globe corectly then the location should be correct. If this is not correct then that suggests the inner hood or perhaps the J tube is from another make of lamp. ::Neil::
Hello! I think that the correct alignment of jet and mixing tube is fundamental to enable an optimal function of the lantern. Otherwise the air/fuel mixture will not be correct and the lantern will likely produce some "odours" when alight. Perhaps some photos might be helpful to give you a more specific advice. BR, Martin K.
