I've seen various version of people doing their brakes, fuel line and other hard line connections. Some use telflon tape on the threads and some don't use anything. I was curious if anyone uses telflon tape on their brake line connections?

 

Nope, I don't use anything on the fittings. They don't use it from the factory. I'd be afraid the brake fluid would eat away at it and then leak.

Barry

50 F-1

 

deleted

john

 

lower...

don't use any type sealer on the fittings... if you made good double flares, they won't leak... the fittings themselves (i believe) are tapered pipe fittings and will seal themselves when tightened sufficiently...

besides I don't think teflon would hold up to brake line pressure.

George can expound on the thread pitch and get you more confused than I have the expertise to do...

john

 

Thanks guys!

 

Years ago I worked for a company that had 300 injection molding machines. They used teflon tape on the cooling hose water fitting threads. They started having so much trouble with the tape blocking the cavities causing complete teardown to clean the water passages that they stopped it's use.

 

Those fittings seal with the metal-to-metal contact on the lip of the double flare. The straight threads on the fitting just provide clamping force. I like to use a small amount of anti-seize on the threads AND on the tubing to provide a little corrosion protection. DO NOT get any anti-seize inside the tube or on the face of the tube. Brake fluid on the threads or the tube just seems to invite massive corrosion and makes taking the fittings apart in the future very hard... Keep the fittings clean and free of brake fluid.

51ford fan, I have seen that problem myself at similar companies. I rarely use teflon tape for anything. NEVER use teflon tape on hydraulics, power steering, or lubrication systems (including engine oil).

 

Wow, great info. I recall my dad use to put teflon tape on just about anything that had threads, other than spark plugs. I remember it use to seal pretty nicely. I installed some brass connections going from the heater hoses to the firewall and then to the heater core. One of them continually leaked ever so slightly. NO matter how much I tightened it, it leaked. I applied teflon tape on it and now it seals nicely. I won't be using it on the brake lines for sure. If I recall, I think teflon tape was used primarily in the plumbing industry?

 

Most plumbers still use the paste type pipe dope. I have found I get 10x fewer leaks in air and gas lines using pipe dope over using teflon tape. Teflon tape is better than nothing tho. The cheap teflon tape that is found in home box stores is almost worthless. I use Mil-spec teflon tape when I do use it.

 

Teflon tape can cause one more problem. It will often electrically insulate when that is not desired (like a sending unit) Pipe dope is better, and only used for coolant. For brakes or fuel leaks, the problem needs corrected. I pulled a lot of TT out of customers malfunctioning carbs over the years.

 

Speaking of sending units...I was going to start a new thread on this, but there are so so many new ones every day...I have seen some companies saying "yes" to teflon tape on sending units, and some "no".
What is the logic between different opinions? Does it make that much difference?
It seems like it would, but if I was so smart I wouldn't be axing

 

Paul

If you teflon tape a sender, sometimes you will not have good continuity to the block (ground). Your common senders are the single terminals that require this continuity, or they can't give an accurate ohm reading to the guage.

 

I’ve had quite a few experiences using Teflon tape. I’ve talked to manufacturers to find out what their recommendations are and I've used it in a lot of different situations. I'm sure the following will provide some talking points based on the previous discussion. It's not a lecture, just what I've found out over the years.

Teflon tape.
According to two major manufacturers, Teflon tape serves two purposes. First, it provides lubrication between the threads and allows you to tighten the fitting without galling. If anyone has tried to tighten two clean brass pipe thread fittings without some kind of lubricant, you're familiar with the high-pitched squeal and the stick-and-slip nature of the adventure. If you've every tried to take apart brass fittings that were clean when they were assembled, and did not have a lubricant/sealant used, you may not get them apart. If you do, the threads will be trashed beyond any further use. Second, the tape seals tiny pockets between threads that can provide a means for fluid or gasses to leak out. The flow strength of Teflon tape is only about 2,000 to 3,000 PSI, so use on hydraulic systems operating at pressures higher than 3,000 PSI will produce limited sealing capability.

Thread types.
There are basically two types of threads used in plumbing fittings - whether it's hydraulic, air, or whatever. The two types are tapered and straight. Tapered pipe fitting have tapered threads, much like a sheet metal or wood screw. The seal is provided by tightening the tapered thread of one fitting into the tapered thread of the second fitting. The increasing pressure on the tapered threads as the fittings are tightened produces the seal.

Straight threads are used on fittings that seal in a wide variety of ways - but they DON'T rely on the threads for the seal. The fellas have already mentioned one example of straight thread seals - the metal-to-metal seals formed by the SAE flares typically used in brake and fuel lines in our trucks. Other straight-thread fittings that do not use the threads as the seal include end-face-O-ring fittings, surface seal O-ring fittings, and compression (ferrule) fittings, among others. Remember, straight thread fittings DO NOT rely on the threads for the seal.


As far as the application of Teflon tape is concerned, ONLY USE IT ON TAPERED THREAD FITTINGS! Almost all the problems (except the electrical insulation that 'fenders noted) come from improper use. There are best practice methods that indicate where on the threads the tape is to be placed, how much tape should be used based on tape thickness and composition (yes, there are several different Teflon tape materials), and which direction the tape should be wound on the pipe threads. Messing up any of these can result in Teflon tape particles getting into the process fluid. I know this is why two major manufacturers DO NOT recommend Teflon tape when connecting their products. I called them and asked. I also suspect it is why a number of others don't recommend it. There is nothing wrong with the Teflon tape, it's just that you need to do it right or you can have a problem. The manufacturers that did not recommend Teflon tape indicated to me that it would perform just fine if we could guarantee that it was applied correctly.

Several national laboratories (Sandia, AFRL, NRL) and numerous industrial labs have conducted tests to help establish general standards for using Teflon tape. From what I have read, there were no system failures (Nuclear, Hydraulic, or Pneumatic) in these studies that could be traced to the Teflon tape used in pipe thread connections. Granted, they were pretty careful when they applied the tape to ensure they followed the proper procedure every time.

Teflon tape is specified in literally thousands of construction standards for buildings, transportation devices, power generation devices, and a number of other applications. You can easily find this out by searching the internet using the phrase "Teflon tape" and the words "ASTM" and "standard". You'll get lots of references to counties, cities, states, organizations, etc. that specify the use of Teflon tape in contracts of all kinds that require tapered pipe thread joints. You can even order pipe thread fittings that come with the Teflon tape already applied in the proper fashion if you want.

If you are going to use it, do it correctly. DON’T use it on straight thread fittings. DON’T apply it so it ends up in your process fluid. If you have any concerns about electrical contact between the fittings, it's probably best to use a little oil-based lubricant instead. Have fun.

 

So basically if in doubt use pipe dope... Labs are "special" places.

There are two basic types of sender units. One requires a ground thru the threads the other has a ground thru wiring connections. Again just use pipe dope.

All of the Hydraulics manufacturers I have worked for or trained with warn against using teflon tape. All too often the tape particles end up in the system and cause problems either during assembly or repairs. For the most part hydraulic companies are getting away from tapered fittings if at all possible but there is a lot of equipment out there.

 

"As far as the application of Teflon tape is concerned, ONLY USE IT ON TAPERED THREAD FITTINGS!'

That's from George's post and deserves emphasis. That is where it is almost always misused. It is not for flare fittings of any kind. It is for pipe thread. You can't patch a bad flare with TT. It just won't last for long if you do.
There really aren't many places on an auto for which it is ideally suited. I use the heck out of it on my household plumbing fittings when pipe dope isn't handy.