Hello and good morning. I’d like to introduce myself as a new member. I’m a stove collector located in northern Germany. I’ve been collecting for many years, mainly Primus and Optimus. My favorite is the Primus 96 and its lookalikes (Radius, Optimus, Thermidor...). Many other stove models have also found their way into my collection. My fascination began with the Optimus 535 on my father’s sailboat when I was still a child. Now I’d like to share my method for removing stuck NRV valves when the valve head is already damaged and rounded off and any standard tools fail. For this, I made a tool out of chrome-vanadium steel from an pin punch tool. Using an angle grinder, I shaped an NRV wrench that is slightly hollow on the inside and has a sharp edge. I clamp the tool in my bench vise and then place the stove onto the tool. By gently pressing the stove against the tool, I turn it, and the sharp edge bites into the softer brass and does not slip. Using this method, I have had success with all problematic NRV without having to desolder the pump tube or any drilling. I’m glad to have found this forum.
I like you already. Many problems can be solved with a 4 1/2" grinder (ok 115mm for those on the continent). Thank you for sharing your method, it's always a bad feeling when a pump valve won't come quietly and the more tricks we all have available the better. Welcome, I look forward to seeing some of your collection...
Ive had to remove a few pumps to get sheared off NRV's...definitely not for the weak minded haha. Good tool!
I kind of thought removing the pump to get to the NRV was initiation for membership here. I enjoyed my experience.
Hello Jack, and hello from Bavaria(Nördlinger Ries). Do you know the Pelam-Forum? When I see so demaged Screwheads, I ask me why not been changed earlier? Have a nice Day Markus(RJ)
Heat the tool up a bit (not hot enough to melt solder) to transfer some heat to the NRV. This also helps loosen a stubborn NRV.
Do you think that would help, rather than just very slightly expand the pump valve body making it tighter in the end of the pump tube? My experience of a wide variety of old machinery is that heat only tends to be effective when both the male and female component have gone through at least one heat and cool cycle well above soldering temperature, ideally red heat where any chemical or oxide bond also gets broken down.
When using a standard NRV tool, I've been experimenting with boiling water and freezer. I could not find any difference. The NRV were still stuck. With my new tool, i just unscrew them, and they come loose with a jerk. No harm to the stove.
Often the force needed to release the nrv can break the pump tube or tge soldered joints. No matter the tool used. Penetrating oil beforehand can possibly reduce the risk.
I heated one of my tools too much and the bottom of the pump tube dropped out, had to then unsolder the pump tube. Duane
Hi. Like you Im glad to have found this forum. Your NRV removal tool, the cut out I presume is slightly less than 5mm. When this was done did you hammer one toe inwards and then shape with a file to a point. Thanks
I made the tool by eye and with a new NRV as a reference. The shape is made by tilting the cutting wheel only. There may be more professional ways to make tools like that, but it worked well for me.
Thanks for that info. I am a member of our local MenzShed so will have a go at butchering a punch, needs must, next visit. Hopefully I can let you know of a successful result. My collection at present; two PRIMUS 96, one PRIMUS 97 and a PRIMUS 100 The 96 that I’m having a problem with belonged to my father hence my need to get it going again. Others have been donated.
@Jack Tar I've got a couple of stuck and rounded off non-return valves. Can make and send me one of your removal tools? If so, send me a private message and I'll gladly cover the cost of your work and the postage. Thanks. Ben
