Teflon Tape

[aero3113]

Is it ok to use teflon tape on fuel lines?

[Plymouthy Adams]

only if the fitting is NPT and then try to leave the bottom two threads void of the tape to prevent accidential ingestion into the fuel system

[aero3113]

What does NPT stand for?

[Young Ed]

national pipe thread?

[aero3113]

I knew that:D

[Joe Flanagan]

No Put Teflon

[Norm's Coupe]

Actually, the fuel line fittings should seal without any sealant just by tightening them. You don't use a sealant on the rubber hose for the filter, just a clamp, and it doesn't leak.

[michael.warshaw]

teflon is lubrication, for the threads and yes its a good idea, it prevents binding.

[Norm's Coupe]

teflon is lubrication, for the threads and yes its a good idea, it prevents binding.

The only time I've ever had a brake line, or a gas line bind at the fitting is when it was rusted. At that point, you may as well cut it off anyway as the line should be replace at that time.

[LuckyDevil]

It is also used as a bit of a barrier. If you have an edelbrock carb, and put a fitting in the back for your brake booster, you would want to use teflon because of the two different kinds of metal. Dissimilar metal corrosion. It will cause the threads to bind or gaul, and can cause the threads to mess up. As for fuel lines, I don't think there is a problem with using teflon on fuel lines. Just my opinion.

[randroid]

teflon is lubrication, for the threads and yes its a good idea, it prevents binding.

Michael,

I've followed your posts and this is the first time you've had something productive to add, so far as I've seen, and I want to congratulate you on getting more involved in your project and on this forum. Kinda gets into your blood after a while, eh?

Welcome aboard (finally)!

-Randy

[Don Coatney]

So far Tim Adams has posted the only correct answer. Tapered pipe threads require a sealent or "pipe dope" to properly seal the threads. Lubrication has nothing to do with it and use of pipe dope will not prevent dissimilar metal corrosion. On tapered pipe threads the pipe dope only fills the void between the threads. There is still metal to metal contact. Flared tubing fittings do not require any pipe dope as the flare seals the connection not the threads.

So to sum it up...

Use teflon tape or any pipe dope on all tapered pipe threads.

Do not use teflon tape or any pipe dope on flared tubing fittings.

[Plymouthy Adams]

I do recommend the teflon tape contrary to some folks belief here and the importance of not placing it on the lower threads..in the olden days the NPT was better know as National Pipe Taper...as the thread are cut on a taper...as you tighten the threaded section it get wider at the top promoting a seal...the problem lies in the fact that the use of aluminum in the auto industry combined with multiple off and on cycles of these threaded parts causes some distortion and with each increaded torque cycle to seal against leaks expands the metal of most aluminum housings...it is for this reason and the increased torrque to stop slight leaks that over tightening will cause cracked inlets and s stripped out threads. The use of the teflon tape will give you an increased margin on the contact surfaces filling minute imperfections and allow a seal without having come close to bottoming out threads...liquid pipe dope is similar in it ability to seal but this stuff really hardens thus I do not recommend it beyond application on black iron piping..for most application on the old mechanical fuel systems we are talking about pressures that usually do not exceed 7 lbs on the fuel system.

[michael.warshaw]

Michael,

I've followed your posts and this is the first time you've had something productive to add, so far as I've seen, and I want to congratulate you on getting more involved in your project and on this forum. Kinda gets into your blood after a while, eh?

Welcome aboard (finally)!

-Randy

thanks, but your wrong i have commented on many things, which has helped people.

[martybose]

I do recommend the teflon tape contrary to some folks belief here and the importance of not placing it on the lower threads..in the olden days the NPT was better know as National Pipe Taper...as the thread are cut on a taper...as you tighten the threaded section it get wider at the top promoting a seal...the problem lies in the fact that the use of aluminum in the auto industry combined with multiple off and on cycles of these threaded parts causes some distortion and with each increaded torque cycle to seal against leaks expands the metal of most aluminum housings...it is for this reason and the increased torrque to stop slight leaks that over tightening will cause cracked inlets and s stripped out threads. The use of the teflon tape will give you an increased margin on the contact surfaces filling minute imperfections and allow a seal without having come close to bottoming out threads...liquid pipe dope is similar in it ability to seal but this stuff really hardens thus I do not recommend it beyond application on black iron piping..for most application on the old mechanical fuel systems we are talking about pressures that usually do not exceed 7 lbs on the fuel system.

What most people don't realize is that there are more than one class of NPT fittings. Naturally I don't remember the designations any more, but the more common class requires a sealant like pipe dope or teflon tape, but the second class of NPT has a slightly different thread profile and is designed to seal dry without any sealant.

More trivia for the multitude ......

Marty

[alan32433]

I had a fuel leak at my fuel pump where the brass fitting is installed. I tried everything including teflon. It disolved and didn't stop the leak. I also tried silicone but that also didn't help. After doing some reading, I bought permatex high performance thread sealer that advertises use with gas and diesel. I've heard other people say yellow teflon will work but I've never tried it.

[DutchEdwin]

What most people don't realize is that there are more than one class of NPT fittings. Naturally I don't remember the designations any more, but the more common class requires a sealant like pipe dope or teflon tape, but the second class of NPT has a slightly different thread profile and is designed to seal dry without any sealant.

More trivia for the multitude ......

Marty

Marty,

You are correct.

B.t.w. I've never seen tape being used in any car tubing.

If the fitting is no longer sealing off, replace the fitting. It is probably damaged. You can try locktite or any other thread sealant. Ok if it works. But I prefer replacing it.

[chopt50wgn]

No one said anything about the Teflon sealant in the tube. I have used that on NPT threads and other places on a vehicle, even used in the home on plumbing . It works well and seals.