I received my nrv wrench from Stu today so I got right to work on one of my 96's. I had been soaking the nrv in PB Blaster so it came out easily. I replaced the lead nrv washer, the lead tank washer, the filler cap seal, the leather pump cup with a Sefa and the nrv pip. I reinstalled the nrv but was not sure how tight to torque it down. Its pretty tight. I fueled it up and away she went, running well. However, I was getting a drip where the pump screws into the fuel tank. Is my nrv not tight enough? Too tight and deforming the lead washer? Any advice please?
Do you mean kerosene is coming up the pump tube and coming out around the pump tube housing cap? Around the pump rod? If the NRV is sealed properly, maybe you didn't seat the pip properly. You may try pushing the pip with a wire, through the hole in the NRV. I would empty the stove and do the dunk test. Ken in NC
Yes, Ken, kero is apparently coming up the pump tube. If I remove the NRV at this point to check the pip can I reuse the NRV washer or will it need to be replaced again?
I have had both experiences. Most times the washer stayed at the bottom. (That's my experience, I'm new here) If you think the NRV is sealed then try resetting the PIP first. A paper clip should reach the PIP. It may take several tries. Do the dunk test before adding fuel. There are stories of fuel spraying from a stove while burning, so do the dunk test before flame. Do you have a reserve cap for the stove? If so, put it on, pump it and dunk. After that is good, then put the burner on, pump it and dunk, there should only be bubbles at the jet. Ken in NC (More experienced members than I will come along soon)
I checked the pip with a paperclip and it is moving freely against the spring pressure. I put the wrench on the NRV and tightened it a bit further. I'm thinking it was too loose. Given that the NRV is usually really hard to remove I assume it should be torqued pretty darned tight.
As above. Also check: If you remove the NRV again, the mating face on the bottom of the pump tube in case a previous owner has scratched/gouged it, making it difficult to seal, even with a lead washer. Ditto the tapered sealing face of the NRV pip carrier to pip face. The NRV pip, check it is able to seal. I have found on two occasions now (a Primus 96 and a Radius 20) that the pip cup is quite deep, using a relatively thin pip meant that the cup bottomed out, allowing fuel to pass. Check the pip cup/spring assembly slides up and down freely in its barrel also. If all looks OK and theres still a weep, perhaps your pip spring is getting soft. Also, a couple of squirts of oil down the pump tube and a few swift pumps often helps to seat everything correctly. Happy fettling! Great little stoves!! Alec
Thanks, Ken! This is my first kero burner. Really like these stoves. I just popped the NRV on my other 96 (1937). It was a bit tighter but came out just fine with Stu's tool. It appears that there was no washer under the NRV. Anybody else ever encountered this?
On the other 96 it was stuck at the bottom of the tube and I had to pick it out. I'm not seeing/feeling one here.
Yep, no lead washer happens often. It's happened in all of my stoves except for a couple that had the lead washer. Doesn't seem to matter the brand. Shhhh, don't tell anyone, but I've been using Viton O-rings on my NRVs instead of the lead gasket and get a perfect seal. Your results may vary but I've had nary a problem. I've done this to probably a dozen stoves, most of which didn't have the lead washer. (Psst, I actually hate the lead washer.) The Viton O-rings are tough and, of course, fuel proof. I know, it's not original. Well, cork is original and no one is putting cork back in their NRVs. Add a little oil to the seal, just like when you change your oil filter on your car, and wham, doesn't leak one bit. The rim of the NRV keeps it contained within the well of the pump tube. sam
I really don't know what size I'm using. I find one from a Viton O-ring kit I have that fits around the NRV shaft and go with the smallest that will fit. Just be aware that I've been flamed about using O-rings on the NRV before because it's 'not original' or 'it will not seal properly', so you must use caution and keep this between us. Here's a sample kit from amazon: Viton O-Ring Kit sam
Hi Sam, using o-rings made of Viton like you did is pretty much OK, the problems start when people use non-fuel resistant o-rings (even Nitrile rubber is known to fail, it did fail me! But only in pips and fillercap seals). When they get soaked in fuel they start swelling and/or decomposing. As you'll surely understand, this is a not a safe situation. Also, it is difficult to remove the NRV with the swollen rubber (I had a problem with one like this ). It is possible to replace the lead washer with PE ones made out of plastic milk bottles and the like (fuel often comes in plastic 5liter cans and bigger, this is purrfect material!). But, like I said using Viton like you do should not give any problems! Be sure though not to over tighten them. These little N°96s are really wonderful stoves! I might have this wrong, but did they not appear in the catalogs in 1904? Not bad for a 110year old design! All the best for 2015, Wim
When I ordered the parts for my stoves I got some HDPE NRV washers in addition to the lead. I might give those a try today when I reassemble.
I actually like the lead washers, they work well and are easy to fabricate. That said, I also have nothing against viton o-rings. Whatever works safely is what to use. I got thrown off one surplus military rifle board over using what worked instead of what was original. I survived it and have gone on with my life, happily shooting my rifles and not worrying obsessively over the "correct" parts and ammunition. Pretty much the same situation with old stoves and finding parts to keep 'em running. Now if only I can get the burner bell off the lipstick jet on my Optimus 96L. They are well stuck together and I don't want to damage anything getting 'em apart. I've been pondering the problem for months. The stove, however, works like a lil' champ even though the parts are stuck as if they were welded. Gerry
Hi Gerry, have a read through this thread: https://classiccampstoves.com/posts/2446 Best Regards, Kerophile.
