# Permatex thread sealer for fuel line connections



## ol sarge (Mar 13, 2013)

I just bought a new to me 1974 20 hp Merc and had to buy a fuel tank to go with. To connect the fuel line to the tank I have to use a threaded connection and it says to use a sealer on the threads. I have read various things about teflon tape for the threads and did not want to go that way. I picked up a tube of Permatex 2 form a gasket sealant non hardening. it says that it is gasoline resistant. Will this work or should I use sometime else to seal the threads? thanks.


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## NautiBuoys (Mar 13, 2013)

Do not use teflon tape, as you say. It will disintegrate into strands and small chunks which could get sucked up into your engine and cause you problems. I have used Permatex #2 with OK results but have had better results (less gas weeping) using Permatex #1 (hard).


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## ol sarge (Mar 13, 2013)

Thanks for the tip. I will try the #1.


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## PATRIOT (Mar 13, 2013)

NautiBuoys said:


> Do not use teflon tape, as you say. It will disintegrate into strands and small chunks which could get sucked up into your engine and cause you problems. I have used Permatex #2 with OK results but have had better results (less gas weeping) using Permatex #1 (hard).


Ooops!
Should I remove the Teflon tape that's been on my tanks for 13+ years??? :?: :?: :?: :?: :?: :?: :?:


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## JMichael (Mar 14, 2013)

PATRIOT said:


> NautiBuoys said:
> 
> 
> > Do not use teflon tape, as you say. It will disintegrate into strands and small chunks which could get sucked up into your engine and cause you problems. I have used Permatex #2 with OK results but have had better results (less gas weeping) using Permatex #1 (hard).
> ...


Same here. I've been using so long on so many things that I can't even remember them all. But I do make sure I don't get any tape over the end of the fittings when I apply it. That way it doesn't end up inside the tank, it's just between the threads. But I've never heard about not using it around gas before so I guess I'll do some research.


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## NautiBuoys (Mar 14, 2013)

Per my buddy who is a plastics engineer, gasoline is made up of 2 teflon breaking down components, benzene and cycloalkenes. Benzene will dissolve the coherent bond of teflon, and the alkenes will break down the chemical bond, leaving one with a white goo. Your call if you want to take the risk of it getting into your engine/carburetor/needle etc when better choices are available.

Besides that, white teflon tape was not designed to seal a threaded joint; it was designed to reduce friction and while it may have worked for you, it's not recommended. Other specialty teflon tapes are available for sealing, gasoline etc but we're talking the cheap white teflon tape here.


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## ol sarge (Mar 14, 2013)

So what is the best way to seal the threaded connecting?


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## crazymanme2 (Mar 14, 2013)

I've used aviation Permatex with good results.


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## whistler (Apr 2, 2013)

NautiBuoys said:


> ........................
> Besides that, white teflon tape was not designed to seal a threaded joint; it was designed to reduce friction and while it may have worked for you, it's not recommended. Other specialty teflon tapes are available for sealing, gasoline etc but we're talking the cheap white teflon tape here.





ol sarge said:


> So what is the best way to seal the threaded connecting?



I don't suppose I've ever seen any teflon tape other than that cheap white stuff. An many packages say it's for sealing threads. As ol sarge says, Come back and help us with this one.


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## muskiemike12 (Apr 2, 2013)

The yellow teflon tape is approved for gas fittings.


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## NautiBuoys (Apr 2, 2013)

From Wikipedia:

The use of PTFE tape in tapered pipe threads performs a lubricating function, which more easily allows the threads to be screwed together, to the point of deformation, which is what creates the seal. 

Uses
Thread tape is appropriate for use on tapered threads, where the sealing force is a wedge action. Parallel threads may not seal effectively with or without tape, as they are intended to be sealed by a gasket.

Thread seal tape is most commonly found in the color white and is used in plumbing applications, but it is also available in various colors. White PTFE is single density, yellow is double density and pink is triple density. It is often used to correspond to color coded pipelines (US, Canada, Australia and New Zealand: yellow for natural gas, green for oxygen, etc.). These color-codes for thread sealing tape were introduced by Bill Bentley of Unasco Pty Ltd in the 1970s. 

White – used on NPT threads up to 3/8 inch
Yellow – used on NPT threads 1/2 inch to 2 inch, often labeled "gas tape"
Pink – used on NPT threads 1/2 inch to 2 inch
Green – oil-free PTFE used on oxygen lines and some specific medical gasses
Copper – contains copper granules and is certified as a thread lubricant but not a sealer


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## ol sarge (Apr 4, 2013)

OK. I just talked to my marine dealer (he has been in business for over 25 years) and he said what he uses on all of his threaded gasoline connections is Loctite #567. He said the permatex is OK and that the teflon tape is ok also as long as you do not go past the threads (it will break down and plug the system). So I guess if the Loctite is good enough for him, it is good enough for me.


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