Here is my nrv tool, I had to find a tube that fitted snug inside pump tube, 3/4 plug remover cut to 92mm, then decided to use one of my father's taps as the tool end as very old Britishsteel, a5/8 b.s.w fitted with little grinding inside plug socket. Tool end was ground an opposite end was ground to take a ten mil quater drives socket , because of the shape of tap an shape of plug end of socket there is no give between the two (perfect) as you can see in photo. I hope that at least one person at cpL can use this information. Gozzy
interesting , i mean this constructivly i would be very cautious how much force you exert on the tap. i know how easy they are broken , cheers kerry
Another word of caution: The Coleman experts over at Coleman Collectors Forum say that it is only in exceptional circumstances that a Coleman check valve (as distinct from a primus-type NRV) needs to be removed. Because of its design and construction (one moving part) the primary cause of failure is the check valve ball getting coated in fuel residue and sticking. The recommended service of a Coleman check valve is soaking the pump tube in pain thinners to dissolve built-up lacquer in the check valve and pumping thinners through the check valve from the pump tube. I've only ever needed to remove one Coleman check valve and that was because it was not seated in the end of the pump tube properly (probably because someone before me had tried to take it out. I bought a Korean-made check valve tool to do the job. Here is a link to a cutaway of the standard Coleman check valve: http://classiccampstoves.com/threads/coleman-check-valve-cutaway.18604/ Cheers Tony
I just noticed this post here from Flivver on servicing a Coleman check valve: http://0flo.com/index.php?threads/1774 Cheers Tony
i may have been a bit quick / rushed and put a bit to much force on a tap . broken a number of them . or when tapping hard components . i may not put it into perfect wording . thats the way it is . either believe and take heed . or just do it your own way . it is not my check valves that may be buggered cheers kerry
The proof is in the pudding! The check valve in question was in a rusted out 639 which released pressure back through valve as fast as you pumped it in an no amount of soaking valve fixed the problem it has to come out. After trying many tools to no avail an actually asking at cpL if I could lone one covering postage which obviously didn't happen I decided to make one. It worked perfectly first time! Can't help but feel criticism more than unity Gozzy
Hi Gozzy, glad it worked and turned out well for you!....That's all that matters really?..... ... you had tried everything else then decided to solve it yourself with what came to hand..... ...Hurrah!...Success!....Well done and thanks for sharing it......Detailed photos say so much...I am encouraged by what you've done.... ok, maybe some would have done it differently but your way worked....Result! ...To be fair I too have had run in's with taps breaking, sometimes for no apparent reason, but most metal can be re used with some heating and tempering.... ...Good luck with future fettles !...
Gozzy My sincere apologies if you had the impression that I was criticising you. I'm glad you got your check valve sorted. I was trying to point out to first time Coleman fettlers that might stumble across this thread, that the non-invasive technique should be used before attempting to take out the check valve. Hence my link to the cutaway to show the check valve setup is not like the standard European NRV. I know Kerry pretty well and I think he was just being honest about his own disasters. Great result for you, and again I'm sorry if I came across as critical of your fine efforts. Best regards Tony
Hiya Tony, absolutely no need for your apologies i understood what you were saying an i would like to thank others members for there words of understanding an encouragement. I personally feel no matter how many years you have been plying your knowledge to what ever takes your fancy there is always room to learn more even from somebody with less knowledge, we all have to be open to teach an be taught. As said before if one person at cpL can gain anything from my pictures an post I'm happy Gozzy
...that's the trouble with taps And drills ..especially the smaller ones..... they 'De'-construct all too readily....
Gozzy, I agree that there are some instances where the check valve has to be removed for servicing or replacement. If the steel ball is rusty or pitted, no amount of cleaning in situ will help. The chances of damaging the fount is lower on steel founts than on brass founts. The danger of damaging the check valve slot can be minimised by grinding the sides of the blade of the tool perfectly parallel and square with no rounded sides or edges so that it will not tend to ride out of the brass slot when you apply torque. Once the check valve is out and the ball and seat are clean, a few gentle taps with a hammer and mild steel panel pin on the steel ball will help it to seal well on the brass seat again. I've encountered a few very old lamps and lanterns where the ball is brass and not steel and would not recommend tapping them.
Good suggestion tapping with a hammer,Phil, I haven't seen that one before, but I may have missed it if it has been talked about here in the past.
A note of caution - the sheer amount of force that I have had to use to undo some of these may be enough to shear your tool - I'd get a manufactured one if you expect to be doing any more than the one. They have the advantage of a threaded rod through the center to keep the valve tight to the tool. Other than that, nice one!
Is there a technique using heating/cooling to make taps less brittle and give the steel more tensile strength? My tool is made from a 16mm high tensile bolt. The blade is the full width of the bolt. The bolt is sleeved in a piece of 20mm PVC pipe. It is a perfect sliding fit in the pump tubes.
Hi Phil, yes, there are various ways to take the hardness out of taps, but you need to know what the taps are made from really..... ...the older high carbon steel ones are probably the simplest to sort out..... ...the HSS are best to normalise/anneal the best you can.... ...some of the cheaper Draper type of thing may be case hardened so probably best left alone... If in doubt then prepare/grind the end to what you need....Heat the end to Bright Cherry Red until the colours run to about 1/3rd down the tap, then push into pile of dry coke dust (not coal dust) and leave for a few hrs then with suitable Eye Protection try turning with the tip in the vice.... if all well then it should give/twist a little...
