SleeperZ Posted June 26, 2012 Author Share Posted June 26, 2012 I'm not one to overtighten anything at first. And I do not believe I did in this case, but it leaked from the get-go. I'm thinking thread sealant may not fix this, but I have to try as I have no time to get this PITA on the track. I really don't want to do anything that will make repair impossible, so JB Weld is out, but this really sucks. Honestly, I've assembled lots of threaded fittings before, on this fuel system and other projects that never leaked. I still think the rail threads were cut too deep as the bushings threaded in a ways before they tightened. Quote Link to comment Share on other sites More sharing options...
pallnet Posted June 26, 2012 Share Posted June 26, 2012 Sir I didn't know this thread existed or I would have chimed in a lot earlier. I know that anything can be subject to a mistake or failure for one reason or another. I'm stumped as to why you didn't contact me on this if you are sure this is one of mine. Please email me with pictures at different angles of your assembled rail and the area of the problem. Pictures of the part leaking will help as well. I have very few issues compared to the number of rails I have made but when contacted I do my best to help solve the issue at hand. Thanks pallnet@hotmail.com Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 26, 2012 Author Share Posted June 26, 2012 (edited) Sir I didn't know this thread existed or I would have chimed in a lot earlier. I know that anything can be subject to a mistake or failure for one reason or another. I'm stumped as to why you didn't contact me on this if you are sure this is one of mine. Please email me with pictures at different angles of your assembled rail and the area of the problem. Pictures of the part leaking will help as well. I have very few issues compared to the number of rails I have made but when contacted I do my best to help solve the issue at hand. Thanks pallnet@hotmail.com I appreciate that. It sounds like it is one of yours, but I bought it from another member here. It was in new condition, but since I did not get it from you directly, I didn't think it was appropriate to come to you for support. I hope you do not take my public posting of this as a slight on you, I do not intend any disrespect although I feel I have been a bit inappropriate. The leak has never been severe. It just gets moist with fuel after a couple of pump pressurization cycles when I was attempting to time my MegaSquirt; I'm not sure if I could photograph it. Anyway, my original configuration was a hex-ended brass bushing with a 1/2" NPT makle thread into the rail, which came close to bottoming out. Presuming TonyD is correct, I may have over-tightened it; perhaps the deeply cut threads made the assembly more sensitive to over-tightening. After thoroughly over-tightening the original bushing, I replaced the bushing with a new one, same type, and went through the same routine and had the same results. Now I have replaced the bushing with a 4" long brass pipe nipple; the threads have a steeper taper on them compared to both bushings. Perhaps that is the root of the problem... I do not feel I over-tightened it at first, at least no tighter than the bushing (at first), but I tightened it to a ridiculous level after that falsely thinking it would seal eventually. I got some Permatex thread sealant last night, disassembled the joint and dried it, and reassembled the pipe nipple into the rail firmly, and not particularly tight. It is now sitting, I have not yet pressurized it. I hope it will seal when I test it tonight. I welcome any additional input; if it does not seal I am afraid I may have to remove the rail and install helicoils. I am getting really sick of the smell of gasoline. Edited June 26, 2012 by SleeperZ Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 27, 2012 Share Posted June 27, 2012 Yes, the key is in the root of the female threads (and of the roots in the male thread going in!) If they are not completely clean... I mean with alcohol or chlorinated solvents so bare, dry metal is available, a 'leak path' can develop. Oil will sit down in there. If you have a burr on the peak of a thread that grinds through the root in the female thread it makes leak paths. In some cases I've used fine lapping compound to lightly 'work in' a fitting and take off nibs, nicks, and burrs with a swiss file before assembly. If you can get the proper Loctite Primer, it makes a GREAT cleaner and final-prep for the stuff. I will apply it to the male pipe threads after priming (and priming the female threads as well) and put my finger over the gob on the pipe to make a nice, smooth surface equal to the peaks of the threads. This pushes the sealant 100% into the roots and you can feel anything on the peaks that may cause problems. It doesn't need to be on thickly, pushed in making 100% root contact on the male threads, I will turn it in a few turns, then back out just a bit (kind of like tapping a hole) to insure the sealant is transferred completely between the first few threads on the female hole all the way to the root. I may go all the way in finger-tight quickly remove it all the way, re-smooth the surface, and then back in finger tight and 1/2-2 turns more. I find that working it slightly back and forth to 'work in' the sealant while finger-tightening seems to have a good effect. Once you put a wrench to it---DON'T BACK IT OFF! Carefully turn it to where it needs to be and STOP. I sometimes wipe the round bead that forms around the base of the male part...other times I don't touch it until days later to make sure the anaerobic action has worked from the bottom all the way to the top. I picked a lot of this up working on hot aircraft hydraulic systems. 165F and 6000psi tends to find leak paths on NPT. That's why they went to an MS-Straight thread O-Ring seal fitting design (which also allows for positionable fittings!) Ideally, the fittings on the end, if going to be adapted to an A/N fitting should really be an MS-Straight. Much more reliable in terms of leaks, and ease of positioning for various configurations. I digress... Good Luck in the morning! Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 27, 2012 Author Share Posted June 27, 2012 Pressurized it, seems to be holding! I'll keep my fingers crossed, but so far so good. Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted June 27, 2012 Share Posted June 27, 2012 It is always interesting learning all this data on fittings and joinings. Your company want an apprentice for thou Tony? It would be an education OP. Let us know how it holds up after a few dozen fuel pressurization cycles... Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 27, 2012 Share Posted June 27, 2012 A guy that speaks Chinese... PM Me... Factory is in Shanghai--Songjiang. You know the deal, never let on you speak anything... Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 21, 2012 Share Posted July 21, 2012 Update??????? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted July 23, 2012 Author Share Posted July 23, 2012 No leaks but it's not like I can drive the car yet. I have yet to sort out my ignition issues, so until I can get on the road, I can't finalize the repair. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 28, 2012 Share Posted July 28, 2012 AHA! Well that's something at least... Quote Link to comment Share on other sites More sharing options...
DuoWing Posted July 26, 2014 Share Posted July 26, 2014 (edited) I found this thread when I was running into the same problem. I've never had much luck with the sealants. Perhaps it's just me. On my original pallnet rail I just used JB Weld as recommended, but later on regretted it because now I can't change the fittings. When installing the barb fittings onto my old professional products fpr with female npt threads I tried sealants that were rated for gasoline and could not get them to seal. Finally I just used the tape, tightened it, and voila it sealed first try. I assembled my new 14mm o-ring rail with permatex thread sealant with ptfe and it seemed to be good. When I finally was going to take the car for a drive I let the car idle for a bit and very carefully inspected and found leaks. I found this thread and took everything apart, got that permatex thread sealant that shows it's recommended for fuel fittings. I cleaned everything nicely with brake parts cleaner, put the one fitting with the sealant in hand tight and tightened it about 1/2 turn. It seems to seal just fine. The other side with the regulator attached didn't seem to seal at all and leaked worse than the first time. Although this time I wasn't running the fitting that was supplied with the rail I was running the anodized black earl's 1/4npt to -6 an fitting so it would match the other fittings on my regulator. This fitting seemed much lighter and cheaper, so maybe the fitting was partially at fault? Took it back apart, cleaned it up nice, ran my harbor freight 1/4 npt tap through the rail threads, and ran the original pallnet fitting through the die and they both went through nice and smooth. Cleaned it up, put some more sealant and bolted the rail in, hand tightened the fitting, then did about 3/4-1 turn. Ended up having to put nearly another turn on it to get the regulator to sit where I wanted, then I pressurized the rail and so far see no leaks, so hopefully I'm good to go. This seems like a really good thread that everyone should see. Also one thing that came to mind, would the fitting that is carrying the weight of the fuel pressure regulator potentially need more tightening than the other side which is just your standard hose barb? Edited July 27, 2014 by DuoWing Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 27, 2014 Share Posted July 27, 2014 Tightening of NPT Fittings is done regardless of what they are on---it's all the same. Weight should be supported properly, but given the weight of an FPR we are talking nothing in comparison with the cross-sectional size of the fitting and it's weight-carrying capacity. The problem with leaks on NPT's are dirty fittings, overtightening, and improper use of sealants (or a combination of any of them!) PTFE Tape when improperly applied (and in some cases even properly applied) can and will contaminate a system. There is good reason for it's prohibition on critical systems. Quote Link to comment Share on other sites More sharing options...
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