Hi All I have just fitted a new generator to my 639 and the new jet it came with and it burns outside the mantle really badly. With a new generator and nipple fitted it can’t be over fuelling can it?
Hi Wolfie. Great news. I was about to ask if you had made sure the airways were clear and the needle was in the right place.
Back to my first post but this time I made sure the needle is in the correct position but still burning outside the mantle I’m bit frustrated with this after buying it two new generators ☹️
Hi wolfie I was wondering what mantle you were using on it seeing as it's a 500cp lantern a large mantle would be correct. Ian
Yes correct 1111 mantle fitted and was working fine before I buggered up the old gen by cleaning it. Did a test burn without mantle fitted today and things not looking good
How full is the tank and how many times are you pumping it up? Just curious. Doesnt look like you are a beginner at this, just process of elimination in my head
The tank has about half a litre in it and as per the photos the first photo is ten pumps and the other is twenty five pumps. I am a beginner at this I only got my first lamp last year
How is the burner screen? Is it in good condition? Gas tip tight on the generator? Your second picture looks good to me. Has a nice blue flame.
You can't over-fuel it unless the jet/gas tip is worn or loosened. Looks like it isn't drawing in enough air for complete combustion. Have you tried loosening the burner cap to check what's up inside the burner-mixing chamber. Something could have loosened or not in proper order inside the sheet metal burner frame. That can alter the fuel and air path in a negative way.
Do you mean unscrewing the burner head or separating the two halves of the frame? I have had the head off and checked inside and as far as I can tell all was ok. I even pushed a cable down all the holes to check.
Yep, just unscrewing the burner cap. Not separating the two halves of the frame. If you couldn't find anything loose or suspicious within, then it shouldn't be a problem. I'd assume you are using the right type of kerosene as the fuel? Type 1-K kerosene, not lamp oil. Using Amish mixture as fuel in your current situation would likely improve the burn instantly. But then, there could be a few things you might need to check in the long run.
You could do a 70/30 mix of kero/white gas. Or a percentage close to that. The picture you posted above, doing a naked burn. The lantern looks to be burning great. Nice strong blue flame. But it doesn't burn right once you tie on a mantle?
Yes that’s correct It burns as in the photos but when a mantle is tied on it burns outside the mantle. I’ve tried reducing the pressure in the tank but doesn’t help. I’m using 1111 style mantle but have ordered some peerless mantles to see if that works
Your flame picture without a mantle shows clear yellow streaks which should not be there. That excess fuel is what is burning outside your mantle. You might mess with the fuel mix or you can fix the real problem which is the generator.
I suppose you have already fitted in a new generator, tip and cleaning needle? And you're having this issue ever since? Seems a little strange, but you'd never know,...anything could still happen, even with the new parts. The newer generator part # should be 639B-2992. It would have a gas tip/jet orifice of 0.009" in diametre. Is that correct? If it happens to be closer to 0.0095", then white gas or Coleman Fuel would work better than kerosene. If you have a slightly smaller 0.0085" gas tip/jet, (similar in size as one for a Coleman 237), then you can try fitting that in to check the result again. That's still a 500/550cp rated tip for kero-fueled lanterns. Before anything, do check the diametre of the cleaning needle as well. It should be a slight bit smaller than the diametre of the jet orifice. With the burner frame removed and fount pressurized, check that the gas tip is working in good order without lighting up. Release the fuel by turning the knob of the valve. See that it is discharging a straight, sharp stream of fuel vertically, not skewed or fuzzy/dripping or spraying sideways. If the fuel discharge isn't a straight, sharp and vertical stream, then it might not draw in sufficient air into the mixing chamber during actual operation. If so, it needs to be corrected first. (This can also happen if the cleaning needle is still not in the correct lowered position).
Many thanks for all your replies. Yes the part number is correct but I have no way of measuring the hole size of the jet. Before fitting it I noticed it had what I thought was R stamped on the jet. Yes I checked the stream of fuel from the jet and it was fine. I also saw that the design from the old generator and the new generator has changed but the new one says it fits all 639 lanterns.
How long have you run it for since the service? Don’t know why, debris/contamination in the system perhaps, but I’ve found this issue on a couple of lanterns that I’ve done a complete tear down and clean, new generator/vapouriser/jet, correct mantle size and it still burns outside the mantle. But if I’ve persevered with the burn they do sometimes just settle down. Just watch your glass if you’re running a lantern with too much over burn.
I have not run it for long after the rebuild. I could try to run it with the mantle on and no glass or hood and see if it does settle.
Yes, they sometimes do settle down once their overall assemblies get heated up. If I've not mistaken, 'R'-stamped tips/jets would be for the 621, 625 or 635 lanterns. All of them happen to work with Coleman Fuel, not Kerosene. The original(older) K6 generator for the 639A or B should have a 0.0075" gas tip or jet orifice according to the well-known Coleman generator list. Just wondering if that would be a contributing factor for the issue. The cross-sectional-area difference is very significant between that of a 0.0075" jet and a 0.009" or 0.0095" jet.
Sorry my mistake the R stamped jet is for my 635. Need to get my hands on a K6 generator. In the meantime I’ll order another of the new types as I’ve noticed the hole in the jet is off centre and causes problems with the pricker wire
I have experienced this as well on a 237. Damaged jet orifice. The lantern would either operate as what you had experienced or not burn bright at all. In addition, the cleaning needle would tend to get bent and the jet orifice further enlarged. I would need to rotate and and tighten the gland nut of the generator on my lantern to a precise angular position so that the needle could be operated.without getting bent. I had eventually made a new jet and cleaning needle rod as replacement.
@Jacob van Pareen That was a lengthy, tedious and a real pain-in-the-as@# project for me. At that time, I did not have any spare jets that would fit a Coleman. All I had was the existing, very worn, 73-year old jet as reference. Therefore, I had to basically start from scratch. I did not know what Coleman used for the exact dimensions for the jet. So, I made some meticulous measurements of the worn jet and some 'guesstimates' on what the workable figures could be. I had to literally put all those 'imaginative' figures down on paper and came up with an 'illustration' on my PC. I did not do it with CAD tools(don't have any) but by hand/mouse/keyboard using whatever drawing tools available on Microsoft Excel 2007. Therefore, I wouldn't actually call it a real drawing but rather an illustration of dimensions of a 'homemade jet':- With the above illustration, I visited a local machine shop. It does not have the proper toolings or equipment for such miniaturized item. (No mini-lathes. No micro drill bits. No imperial dies). Whatever available in the shop were huge machines for much larger parts. I had already bought some 5/32" square brass stock. Whatever the heck...I just bit the bullet and persuaded the machinist to get on with it making whatever was on the above illustration. Imagine the level of difficulty churning that out on a huge lathe. The chuck was simply too big to hold a 5/32 square bar stock... The subsequent 'behind-the-scenes' work was 'brutal and near unthinkable'for both the machinist and myself.
Wow! That is a benchmark for persistence and courage. I can think of the challenge to drill that small hole with great accuracy and precision! Well done!
I bought some 0.2mm micro drill bits(Dormer) for the job. They are pretty expensive and not exactly available from your regular hardware store. I ordered them through RS Components. Initially, I had a couple that broke off without even completing the hole. What a shame and frustration. The jet on a Colemam 237 has a 0.0085" orifice(0.2159mm diam.). I suppose the 0.2mm drill bit would make a hole that's a tad bit larger than its nominal diametre...so, pretty much would suffice for the job. The shop's lathe chuck had a diametre exceeding a foot.(that'd give you an impression of its size and the awkwardness when the job was in progress). Another smaller chuck had to be clamped on to the larger chuck in order that the 5/32" brass stock could be held. Anyway, making the jet was only part of the story. You probably would not believe how I actually made a new cleaning needle/rod for that Coleman. Well, it was equally crazy: it was laboriously ground with some basic power tools from a single piece of 1/16" inconel weld-filler rod. There was no crimping, no piano wires, no guitar strings, no acupuncture needles and last but not least, no joints involved.(That was only because I can't find any with the right size at that time). Here are some pictures. Left: original. Right: homemade:- Note: The original pricker wire had eventually broken off during use(2nd picture).
I would not believe this, had I not seen the evidence! A new meaning to "where there is a will, there is a way"!
