Leaking flair nuts
Thread Starter
Intermediate
Joined: Sep 2013
Posts: 37
Likes: 0
From: san jose california
Leaking flair nuts
Hey everyone, Happy holidays to you all.
I'm replacing the fuel lines at the engine in my 68'. Bought new steel lines ( not stainless) installed them very carefully making sure the line fitted the mating surface. Had to tweak the lines a bit to get them just right with no tension on the line itself. Ha, leak like sieve.
Anybody got a trick to get then to seal. Dealing with gasoline and hot cast iron. Not a good situation.
I'm replacing the fuel lines at the engine in my 68'. Bought new steel lines ( not stainless) installed them very carefully making sure the line fitted the mating surface. Had to tweak the lines a bit to get them just right with no tension on the line itself. Ha, leak like sieve.
Anybody got a trick to get then to seal. Dealing with gasoline and hot cast iron. Not a good situation.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,753
From: Charlotte NC
Ed T has a good idea.
I am aware of what you have going on and it happens to me. It usually occurs MORE when I am trying to get stainless steel lines to seat.
I verify that the seat in the carb fitting is good and does not have a notch/groove in it due to the line being slightly off when it was put on.
ALSO...when I am putting new lines on with the correct flare wrench...I put it on good and tight...then I loosen it and tighten it back up again and I notice that I get a bit more rotation on the nut when tightening it up. This usually stops the leaks for me. I may have to do this a few times ..but I finally get it...and teh leak stops.
But..the idea that Ed T provided is a good idea!
DUB
I am aware of what you have going on and it happens to me. It usually occurs MORE when I am trying to get stainless steel lines to seat.
I verify that the seat in the carb fitting is good and does not have a notch/groove in it due to the line being slightly off when it was put on.
ALSO...when I am putting new lines on with the correct flare wrench...I put it on good and tight...then I loosen it and tighten it back up again and I notice that I get a bit more rotation on the nut when tightening it up. This usually stops the leaks for me. I may have to do this a few times ..but I finally get it...and teh leak stops.
But..the idea that Ed T provided is a good idea!
DUB
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
I use flaretite inserts on stuborn stainless fittings that won't seal.
Couple of things
Normally I'll tighten, loosen, tighten several times to kind of set the flare to the fitting.
Over-tightening (trying to stop a leak) will frequently distort the tube end and open up the angle so it's trying to seal at the top instead of the side, running the flare tool around it and lightly re-flaring the end will sometimes bring it back.
The other thing is to always put some antiseize on the nut side of the flare so it slips rather than twisting the end of the tube.
Flaretite or the copper inserts work when I give up (usually stainless)
Summit sells some, I think they are Earl's.
Watch the angle, they are available in 37 and 45 deg.
M
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
If the flares on the tubing are formed decently, you just need to tighten the fitting until the leak stops. You definitely need to use a tubing wrench on the tube fitting AND another wrench to hold the other fitting in fixed position. Tighten it a bit and try it again. Continue until it seals or until you think you have tightened enough that you've given up on it sealing.
Use a good bright light and a magnifying glass to inspect ALL surfaces that are affected during the sealing process (fittings AND line). All should have smooth, clean surfaces. If you find rough areas, you should try to clean them up with sandpaper, polishing paper, stone, etc. If it just won't seal and you purchased those parts from a store or on-line, contact the vendor and explain that the items wouldn't seal; also explain what you tried to fix it. The vendor may send you a new part[s].
The advice in the prior post is good if you find that reasonable tightening will not seal the leak.
Use a good bright light and a magnifying glass to inspect ALL surfaces that are affected during the sealing process (fittings AND line). All should have smooth, clean surfaces. If you find rough areas, you should try to clean them up with sandpaper, polishing paper, stone, etc. If it just won't seal and you purchased those parts from a store or on-line, contact the vendor and explain that the items wouldn't seal; also explain what you tried to fix it. The vendor may send you a new part[s].
The advice in the prior post is good if you find that reasonable tightening will not seal the leak.
Last edited by 7T1vette; Nov 9, 2015 at 07:30 PM.
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
You must have explained all this in detail elsewhere, but since I didn't see it I will ask the question: Where exactly is your fuel line leaking? Is it at the carb inlet? Do you have a Qjet carb? If it is a Qjet is the plastic washer intact? I remember removing that very thin little plastic washer, not realizing how important it was, and my fuel line also "leaked like a sieve" at the carb inlet.
Looking at your pics, looks like you have the stock 68 fuel line that screws in and out of the GF 432 fuel filter. Did you change both pieces of fuel line all the way to the fuel pump? Any leaks at the pump or the fuel filter? If it is only at the carb, and it's a big leak, and you purchased the fuel line (so the flares should be well made)..... you may be missing that washer.
Looking at your pics, looks like you have the stock 68 fuel line that screws in and out of the GF 432 fuel filter. Did you change both pieces of fuel line all the way to the fuel pump? Any leaks at the pump or the fuel filter? If it is only at the carb, and it's a big leak, and you purchased the fuel line (so the flares should be well made)..... you may be missing that washer.
Last edited by PRNDL; Nov 10, 2015 at 10:53 AM.
Melting Slicks
Joined: Jan 2014
Posts: 2,478
Likes: 254
From: Downers Grove Illinois
You must have explained all this in detail elsewhere, but since I didn't see it I will ask the question: Where exactly is your fuel line leaking? Is it at the carb inlet? Do you have a Qjet carb? If it is a Qjet is the plastic washer intact? I remember removing that very thin little plastic washer, not realizing how important it was, and my fuel line also "leaked like a sieve" at the carb inlet.
Looking at your pics, looks like you have the stock 68 fuel line that screws in and out of the GF 432 fuel filter. Did you change both pieces of fuel line all the way to the fuel pump? Any leaks at the pump or the fuel filter? If it is only at the carb, and it's a big leak, and you purchased the fuel line (so the flares should be well made)..... you may be missing that washer.
Looking at your pics, looks like you have the stock 68 fuel line that screws in and out of the GF 432 fuel filter. Did you change both pieces of fuel line all the way to the fuel pump? Any leaks at the pump or the fuel filter? If it is only at the carb, and it's a big leak, and you purchased the fuel line (so the flares should be well made)..... you may be missing that washer.
Also make sure you don't have 2 plastic washers going into the Quadrajet as they will cause it to leak a lot.
