After years of faithful duty, my Thermos camping stove has developed a problem that makes it non-useable. When I pump air into the tank, the white gas in the tank backs up through the pump and then out the tank. In short, the pump has a slow leak. It's still good enough to build up pressure, but eventually the pressure is lost. Is there any way to repair the pump?
Welcome to CCS. My wife and I drove through your town, Graham, recently on vacation in the NW. I do not know these stoves in particular, but it sounds like a check valve, probably at the bottom of the pump tube, is allowing fuel back into the pump tube. I would say it is repairable. There should be some way to check/replace/repair the check valve as one does the same to a Coleman check valve or a 'Primus' type NRV. The Coleman check valve is an all metal assembly, but the 'Primus' style NRV uses a fuel resistant 'pip' to seal. Both use a special tool to remove without damage. I would guess the Thermos does also, but I do not know that. What is the model number of the stove? Also, photos help. Ken in NC
Yeah, a photo and maybe the model number would help. I have a couple of Thermos stoves with unusual pumps on them: Thermos 8423 I looked at how the NRV works in them and the design is quite different than the usual fair. Anyways, I've not worked on the NRVs in the pump on mine since they still work, but they might be a little difficult to work with but, hey, there's always a first time! sam
Look at this work done on the Coleman Collectors Forum ..... Link Scroll down to post #23. I think it is the same as yours. Ken in NC
Hi, Ken: I certainly was "lost" on how to make the repair on that pump. But I checked out the link on repair for Coleman and that was close enough for me. I would never have guessed that there was an "O" ring inside that assembly, and I would have never guessed that that pip came UP! There was NOT much space for me to work, but I removed that "O" ring. It was very brittle and came out in pieces. Evidently that ring is larger for the Coleman pumps than for the pump on my Thermos. Mine measured 9mm outside diameter by 6mm inside diameter. Now to find a new "O" ring that same size!!! Gareth "Gary" Bouwman
Gary, in a Fel-Pro Oring set, a number 009 or 010 will work, it is bigger than you think, and a bother to get back in the groove. ALSO I have one Thermos stove that the aluminum end piece leaks where it joins the tube. But some liquid in tube and push down plunger, see if it leaks around tube. A 009 has 11/32 OD, 7/32 ID
Mea Culpa ! Anybody knows that 9mm is MORE than 1/4 inch, which is the O.D. for the Coleman "O" ring. I also believe the pump tube is longer for my Thermos. My local hardware store probably has the "O" ring I need. I thank you all for your assistance My wife needed to know why on earth I wanted to fix an old camp stove. I needed to prove to her that an old stove, as well as her old husband was still use full!
I'm glad you're gettin' yer stove fixed! Once you figure out the seal on your pump, you'll have to fire up the old girl and post some pics! All the best, sam
Be careful using a oring from the hardware store. You need one fuel resistant. Go to an auto parts store. Ken in NC
No worries bout the oring, get it anywhere. Black Orings are all rated the same. They use black Oring in carbs. You can get green ones which are better with modern alcy added fuels. If it fails in a couple years, you know how to deal with it.
Majicwrench If that were true The Fettlebox would sell 'just any old gasket material'. They don't. They use fuel and heat resistant Viton. Failure of a white gas stove is not a minor thing. Ken in NC
Coloured Viton o-rings are used in applications or situations where it may be hard to differentiate between o-rings of another material which are predominately black. Brown or green are the common viton alternatives where you don't want to get them mixed up. Apart from that they are the same as the black viton. Obviously there will be a difference between the fuel resistance of a black nitrile o-ring & a viton o-ring of any colour.
You can make this as compicated as you wish, or you can put a black Oring (like the one that was in there for X years) and use your stove. I tend to find solutions and not problems.
I agree the colored Viton O-rings are the way to go. I use brown, yellow, and light green colored ones on stoves. My car uses the yellow and green ones in the fuel injectors and fittings related to fuel. I've seen different colors on fuel pumps. You can buy a set of Viton O-rings from Harbor Freight as well for $12, they have all the colors you could possibly want. sam
Just be clear. Majicwrench, I meant to be cautious of using o-rings that are not fuel resistant from a hardware store, no matter the color. Ken in NC
I tested a stove before taking it hiking this weekend. Its less than a year old and 2 o rings leaked badly These were both black but what material? I have used hardware store black orings on filler caps and they have been ok but Ill not be trusting them on pumps. A set of viton rings is cheap compared to having a tramping hut burn down with all your gear inside on a dark and stormy night.
Sure, run the vitron if you wish. If you wish to be even safer leave the stove at home, playing with fire is dangerous. What stove had o rings that failed?? How do you what material they were made of?? How do you know what damaged them?? An awful lot of assumptions going on. And as you must know, a fill cap is subject to pressure too, just like a pump.
The stove in question was Chinese so who knows what they were but they were replaced with other black ones off the bench. If you fit viton you wont ever replace them again unless they are subject to wearing forces I have had the standard MSR bottle o rings fail but they were quite old and it was the part exposed to air that started to crack.
Got to wonder about that chinese stuff. I'll bet the "vitron" o-ring set from Harbor Freight come from China, wonder what they are really made from.....
