Cooler lines

[Joel Chapman]

So I traced a leak I was having in my dart to my transmission cooler lines. The previous owner had cut out a section of the line that I assume was leaking in two spots one on each lien and replaced it with rubber line. While I was replacing the lines I noticed that some of the fittings that the flare nuts attach to had Teflon tape on them and some didnt (transmission fittings tape radiator fittings no tape). Do I need to retape all the fittings or use locktite? My repair manual makes no mention of how to properly install these lines. The car is a 71 dart with a 318/904. Thank you in advance for the help!!

 

[Plymouth 65]

Factory didn't use either, I'll use teflon on fittings if there leaking. If not, I leave them alone. 65'

 

[TrailBeast]

So I traced a leak I was having in my dart to my transmission cooler lines. The previous owner had cut out a section of the line that I assume was leaking in two spots one on each lien and replaced it with rubber line. While I was replacing the lines I noticed that some of the fittings that the flare nuts attach to had Teflon tape on them and some didnt (transmission fittings tape radiator fittings no tape). Do I need to retape all the fittings or use locktite? My repair manual makes no mention of how to properly install these lines. The car is a 71 dart with a 318/904. Thank you in advance for the help!!

Flare fittings are not designed for teflon tape, as they are supposed to seal metal to metal.
If they don't then they should be replaced if running them down a little tighter doesn't seal them up.
If you mean where they go into the case then it's probably fine. (though not a real good idea)
If anything is needed for the fitting to case a pipe dope should be used, as teflon tape can get into the trans or cooler unless you really know how to apply teflon on an application like that.

 

[Joel Chapman]

Flare fittings are not designed for teflon tape, as they are supposed to seal metal to metal.
If they don't then they should be replaced if running them down a little tighter doesn't seal them up.
If you mean where they go into the case then it's probably fine. (though not a real good idea)
If anything is needed for the fitting to case a pipe dope should be used, as teflon tape can get into the trans or cooler unless you really know how to apply teflon on an application like that.

It’s not the part of the fitting that the flare nut is going on. It’s the other threads of the fitting. The side that threads into the trans mission that had the tape on it.

 

[TrailBeast]

It’s not the part of the fitting that the flare nut is going on. It’s the other threads of the fitting. The side that threads into the trans mission that had the tape on it.

That's fine as long as whoever did it was wary of tape getting in the trans lines.
Basically you wrap the tape clockwise if you are looking at the trans end of the fitting and don't go all the way to the end of the threads.
Then there's no chance of tape getting in it.

 

[Joel Chapman]

That's fine as long as whoever did it was wary of tape getting in the trans lines.
Basically you wrap the tape clockwise if you are looking at the trans end of the fitting and don't go all the way to the end of the threads.
Then there's no chance of tape getting in it.

So it doesn’t make a difference either way on the end going into the trans what about the fittings going into the radiator? Just again make sure the tape doesn’t go past the threads at all?

 

[TrailBeast]

So it doesn’t make a difference either way on the end going into the trans what about the fittings going into the radiator? Just again make sure the tape doesn’t go past the threads at all?

Exactly.

 

[Demonic]

Teflon tape is bad if you get it past the end of the 1/8' pipe threads on the adapter, like Trailbeast said. Any thread sealant should be kept 3/4 to 1 thread back from the end and never past that to where it would enter the end. I don't like teflon tape at all. It's not to be used on fuel oil devices - it gets partly dissolved, oil valve, pump mfg will void a warranty if Teflon bits are found. It goes against most gas codes. Teflon tape is great if you have junk overseas pipe thread that is too large on the female side or overrun on the male side and need to tighten the fit. If teflon tape gets in the cooler or trans pump it could cause a problem.

Flare fittings seal on the flare, not the threads. Compression fittings seal on the ferrule, not the threads. Teflon tape on a flare or compression fitting can often cause a leak. If you have a leak, something is wrong and must be fixed. Do not use sealant on flare or compression. American pipe is tapered thread, and there is a spec for the thread form. British and other pipe thread is parallel.

Pic of the unloader fitting from my 25 hp air compressor. 1/8 mpt x 1/4 comp fitting got over run into the bushing with teflon tape. A bit of teflon got onto the unloader valve seat, causing a slow leak.