Hi @Peter Ockenfels I believe that the fuel tanks of Optimus and Primus 535 stoves originally had a painted finish. Some people have re-sprayed the tank of their stove when restoring them. Have a look at the photos in this thread: https://classiccampstoves.com/threads/primus-no-535-1955.9455/ Best Regards, Kerophile.
@presscall Great post about a great stove. As I’ve said elsewhere here on CCS, the Heinze Geniol is a great camp cooking stove (when you don’t have to back-pack it anywhere). It features heavily in my “road trip” posts. I’ve not fitted a cleaning needle to either of mine, and I don’t use the inbuilt preheater, being very content with a fibreglass wick and metho - pumping for use of the pre-heater is a pain. (I suppose it’s ok if you’ve got a few new recruits to do the menial kitchen duties ). I use a windshield around the burner, and, when operating out of doors, a 10-plate aluminium windscreen. All in all a versatile, high performance, kerosene workhorse. Cheers Tony
Thanks kerophile Indeed it really looks like the tank has been painted. And I also understand now why the soldered joints look “golden” instead of being “silvery”.. Then I will just clean the tank. Thank you again. Peter
I just spent the day making washers/gaskets for all of the hard seals. I am amazed it ran so well with hardened seals. I had not fettled it since I got it. It has always held pressure overnight, or even longer. Another testament to the quality of the stove?? The manometer seal was good/soft, as was the pre-heater pip. All other viton gaskets were cut. Except for a 4.5 mm pip from FettleBox. I used a 3/4" with a 7/16" punch for the Filler cap. I ordered a 20 MM today for a better replacement. 7/32" punch was used for the SRV. 4.5 mm pip for the NRV. After that the dunk test reveals bubbles at the pre-heater joint and the manometer. Tomorrow is another day. I noticed that my tank has a duller, painted, look to it. My prickers are different, too. One wire out of the end, and a wire laying across a ways down the 'handle'. Ken in NC
Hi @presscall I noticed you opened the safety release valve, what is the size of the viton? My Heinze should replace the viton. best regards
@CaesarV Thickness of the viton would be 2mm. Size (diameter) is determined by the inside diameter of the brass cup it fits into, which you could measure. Regards, John
Hi @presscall Thank you,I opened it yesterday,and bought viton board，I would repair it when the viton arrive.
What a tremendously useful (old) thread. I have an un-issued German version of this stove and due to age a couple of the seals have hardened and now leak. Seeing how they come apart is priceless. Many thanks. I've had it working and it's all good. All except for the minor leak and the skipping on the pressure stroke which has been mentioned elsewhere. It's totally complete with all the tools, sealed spares bag, starting gel and fuel bottle. Hopefully with some assistance I can get it back to 100%. I know they have a small but dedicated following.
Your stove looks grand. I’m pleased it was of help. You mentioned the pump: It’s true these Petromax lantern derived pumps are more inclined to do that than the efficient pump cup mount arrangement on a Primus. Well-oiled pump cup in good condition maximises efficiency. Worse are O-ring equipped pumps on some Optimus (and some other manufacturer) models). HERE I fabricated a better pump for an Optimus marine stove.
Thanks for responding. What actually causes it to skip? The cup washer seems OK in the bore and the NRV, which I have not disassembled seems to function. I can't determine if it's air blowing by the washer on the downstroke or whether it's the NRV effectively jamming and then suddenly opening under higher pressure or a mix of the two. I've other pump stoves which are a smooth as you like. Yes it's a nice piece. It's been sitting in a barn, in a box since the 80's pretty much.
Have a read of THIS post of @kerophile ’s which is an excellent account of the most efficient type of pump arrangement - pump cup assembly moves on the shaft allowing air past the shaft mount on the ‘pull’ stroke, seals on the ‘push’ stroke. On the Heinze Geniol (and Petromax lanterns) the pump cup mount is rigidly fixed on the pump rod and on the ‘pull’ stroke the charge of air can only pass the pump cup around it’s mating surface with the pump tube, breaking the bond of pump leather and tube surface. Re-sealing on the ‘push’ stroke sometimes fails (skips). Well-oiled flexible pump cup minimises the problem but doesn’t eliminate the phenomenon altogether.
Hi @Chris J have a look at my comments on the pump used in a Heinze Geniol Military stove: Heinze/Geniol Military Stove pump fettling. Best Regards, Kerophile
Thanks Gents. My piston is original and has a fixed cup washer at the end with a brass supporting behind the washer for the priming stroke. As you suggest, it does not float at all on the shaft. The inner end is peened over to hold the washer against a small rectangular washer. There is a spare cup washer in the tool kit, but I am unsure how anyone would change this in the field. It doesn't appear that the components will slide off the shaft in the opposite direction at all. It's pretty solid. The down stroke then, relies on two things. 1. a good seal with the tube to force air past the NRV and 2. replenishment of air in the tube. Now to me it feels as though at times, compression ONLY occurs right at the end of the stroke indicating that there isn't really a full charge of air in the tube. Interestingly if I unscrew the cap and pump the piston with a wiggle or two on the up stroke, I seem to get pressure immediately on the return downstroke and I can hear the pssst of the NRV operating. The cup washer does seem to be in really good condition and very flexible. Is it then, sealing too well on the upstroke?
Sorry, forgive me for being dim. I'm new, but I don't really understand the link to the how to replace an o ring with a cup washer - thread. I already have a cup washer piston. I saw the stock of cup washers thread too but again, I don't think I need a new washer. What I do need to consider though if I read you both correctly is to make the cup washer float on the up stroke to be able to pull in fresh air? I have it on my desk at the second and suddenly it's pumping really well. Go figure!
I know, I mentioned it simply to illustrate the ‘ultimate’ solution that I resorted to to rectify a particularly poor pumping action on an Optimus. I see Kerophile also posted a link. Yes, as you say, it’s all down to that upstroke and how complete a charge of air it draws into the pump cup to NRV space. You know, a clue might lie in what you’ve said Chris about it working well when you’ve had the stove indoors. I wonder if it’s down to the viscosity of the pump cup lubricating oil? Indoor temperatures would make it less viscous and the pump leather more flexible. On a bad (cold) day it’s possible to feel substantial resistance on drawing a pump stroke on that type of pump - sealing too well, sticking even, to the bore. Prompt for discussion of best pump cup leather lubricant!!?? - many times there’s been that discussion here on CCS! Thin machine oil’s usually the most advocated. John
Ahh apologies. Didn't mean to mislead. When I said it had been in a barn since the 80's I didn't mean MY barn. It's been in my office for some time after rescuing it from someone else. The cup is actually lubed with light oil so there's a bonus. I've been reading all these threads as an outsider for a while but I didn't come across this particular one. What was most enlightening was the fact that you could further strip the NRV. I didn't know that. So whilst sitting here catching up on episodes of Forged in Fire, I have stripped and cleaned the NRV more thoroughly. It's working much much better now. Interestingly, if I pump the piston and it skips, slips or whatever, then turn it 90 and try again, I can actually find sweet spots where it pumps without issue. On my Coleman stoves and lanterns etc I have experienced the issue you describe. I was travelling in Russia, up in the Arctic Circle and when needs arose, I had to put the piston in my mouth to warm it up. Nice.
