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Double flare won't seal

JimKueneman

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What do you do when you can't get a double flare to seal? I bought a fuel line for the stub out of a 318 to the filter. For the life of me I can't get it sealed. It will drip constantly when it is running and after you shut it off. I removed the line and pressed it in my Snap on flare tool thinking it may be just out of round or something. I am tightening the crap out of it with Snap on crowfeet so it is getting tight....

What else to do?
 
Did you tighten it so much it may have cracked? Are you sure it is a double flare and not just a single?

Tighten it some more. Some times when you think you are really tight and it still leaks it just needs that extra tiny bit.
 
Also, the male flare fitting the line goes to might have a gouge in it now from overtightening the nut.
 
Is the tubing soft, or is it stainless, which often has problems because it's so hard? If there are no cracks and it just won't seal, you can try adding a soft copper washer.
https://www.ebay.com/itm/3-8-Copper...soft-copper-line-water-air-fuel-/381165667616
s-l500.jpg
 
Also, the male flare fitting the line goes to might have a gouge in it now from overtightening the nut.

I only got after it once I realizes it was leaking. It leaks really bad, I would not drive it like it is. Guess the best thing to do is take the fuel pump of and figure it out :(
 
Are you sure it's not a single? Have you checked the female end? Just because you flared it with a Snap-On tool, I would still check the flare for imperfections. Please keep us updated.
 
Look at everything real close....
 
Check the seat as well if damaged no flare will seal
 
I learned this trick 25 years ago. A dab of white Teflon paste on the flare and a dab on the threads. It sounds all wrong I know. Didn't believe it either.Someone had told me and I had one that wouldn't seal no matter what. Tried it and it worked. Been doing it ever since. I can't tell you why it works, but it does. My bet is lubrication.
Doug
 
Is the tubing soft, or is it stainless, which often has problems because it's so hard? If there are no cracks and it just won't seal, you can try adding a soft copper washer.
https://www.ebay.com/itm/3-8-Copper...soft-copper-line-water-air-fuel-/381165667616
View attachment 761617

I agree with this. I was talking with the guys at the shop who are working on my car. They told me they have had A LOT of problems getting stainless steel brake lines to seal because they are so hard they don't move enough to conform to the mating piece. He said they've tightened them until it deformed the mating piece, and still no seal. We chose to go regular steel lines in mine instead of stainless.

The soft copper washer sounds like a good idea!
 
I learned this trick 25 years ago. A dab of white Teflon paste on the flare and a dab on the threads. It sounds all wrong I know. Didn't believe it either.Someone had told me and I had one that wouldn't seal no matter what. Tried it and it worked. Been doing it ever since. I can't tell you why it works, but it does. My bet is lubrication.
Doug

Yea I was thinking that too you can feel it grabbing as you turn the nut. I will give that a try tonight. Also ordered a few of the brass cone washers.
 
This method will seal stainless lines as well.
Doug
 
I learned about those copper seals from the guys at NASA.
I was having a hard time sealing stainless AN fittings on my hydraulic steering system on my boat.
Seco seals is the brand I used and was recommended to me by the NASA dudes.
I bought them from Pegasus (google seco seals or Pegasus)
 
Also, if mating stainless to a brass fitting, they are usually “one and done”. Meaning, once the stainless takes a set on the brass fitting, it will likely not seal again due to the stainless leaving a ring on the brass.
 
Good luck. I have not tried stainless lines because of the stories I hear. NiCu is corrosion resistant and easy to work with if you buy and rebuild a third Mopar.:D
 
Good luck. I have not tried stainless lines because of the stories I hear. NiCu is corrosion resistant and easy to work with if you buy and rebuild a third Mopar.:D

I have no idea if these are stainless or not. They are a VERY shiny metal and not the dull silver color so there is a chance they could be SS.
 
Sometimes, doing a double flare, it can get pushed to one side, making it un-even. Stainless, is a pain from the word go, putting flares on it.
Wonder if that's what happened on your's, off to one side? Doesn't take much, then it leaks.
 
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