Farmall Cub

Im puttin a new cutoff on my gas tank. is better to use teflon on the threads or can i use pipe dope like plumbers use? or what do i need to use?thanks

Teflon tape is ok as long as it is on the threads only and there isn't any excess that can contaminate the fuel. Don't ask how I know that From reading different posts on the pro's and con's of tape versus pipe dope, I am leaning toward the pipe dope as the better choice. I recently saw that my local NAPA dealer actualy had it as well as my neighbourhood Fairview Fittings dealer.

I guess it is a matter of preference. Are you going to use a ball valve for a shut-off/petcock or that little L-shaped thingy I have moved on to the ball valve and really prefer them. No seats to rebuild and no little L-shaped thingy's to drive me nuts from the neuropathy

I got a whole new shebang- ball valve,filter,sediment bowl. I got pipe dope aint got teflon so i reckon i lluse pipe dope thanks mr rudi

You can get your fuel type teflon tape at Tractor Supply for a couple dollars, go that route and save yourself some trouble down the line later...

the old one had teflon on it but it had what looked like shredded pieces of teflon? in the tank. I figured the gas would break down the teflon. But will the pipe dope hold up over time? what will pipe dope do if it gets in the tank? (Im clumsy ! I get oil, pipe dope pvc glue etc all over me! hence the dirty in dirtyred! )

The fuel type teflon tape is made for this kind of area and it will give you better service. Gas will melt the regular type and then you'll have carb problems.
The pipe dope will stop up everything.
Just my .02 worth.

I use either /or and they both work fine. Rudi makes a good point on keeping it out of the gas tank and Yogie makes a good point on taking it apart after using pipe dope. I usually use the pipe dope because I cant find the teflon tape most of the time as it is used by my fasmily and the neioghbors. Go figure that one..

This is what I use. It works well for me.
http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

The one thing I forgot to mention and I am not sure if this is really important or not seeing as the Teflon tape nor the pipe dope is actually supposed to come in contact with the fuel...

The pipe dope that I saw at NAPA and Fairview was for gas lines.. as in LNG or Propane. PFTE or the yellow Teflon tape is also for LNG or Propane lines.



I don't see any thing really called out for gasoline, so I am assuming and Lord I hope I am not making a donkey of myself on this.. that because the fuel doesn't come in contact with the tape/dope it doesn't really matter? I am not sure.. but so far I have not had any issues when the tape is applied properly ie - 1 thread back from the end of the fitting.

I keep researching this though from time to time. I tried this as a search string Teflon Tape or Dope for Gasoline Lines and didn't get a lot of hits that I can see for the fuel line side of the question. However, I like Taunton Press for my Fine Woodworking and the Fine Homebuilding series.. so here is some stuff I found on the Taunton websites..

Taunton's Fine Homebuilding wrote:Teflon tape for residential plumbing is color coded. High-density pink tape is used on water lines; yellow tape is designed for gas-line use. White tape (often low density) is used on water lines.

Tauntons's Fine Homebuilding wrote:Tape is less messy, but there's a caveat: If wrapped wrong (in a counterclockwise direction), the tape can ball up as components are tightened, ruining the seal.

Taunton's Fine Homebuilding wrote:Dope stays gooey. Pipe dope never hardens, so it will never become brittle and flake out of a joint.

From what I can gather reading a lot of this stuff on various forums including a Mitsubishi forumis that as long as it doesn't come in contact with the gasoline it should be ok. Teflon tape and dope was designed originally for NPT type fittings (which are most of what I use, so that works..) and should work on the NC and NF threads as well.

Boy this can get involved

Apparently the white crud I found in the bottom of my carb a while back was caused by the reaction of the benzene and cycloalkenes. But that is only if the tape is in contact with the gas when applied incorrectly as I had done once. You can see the white gooey residue in the bowl.



Now that I understand the ramifications I use the 1 thread back method and I haven't had any leaks or any build up in the carb.

The other product that I found at NAPA is by Permatex.. but I haven't tried it yet.



This is called out for fuel line fittings, so maybe this is what I will probably go to for pipe dope

Oh, I see Don just posted a link to the Permatex site as I was refreshing this to post.

I like and use the Permatex Product that Don recommends in his post.

This product is a one fits all type of product, as it is reccomended for pipe taper and stainless fittings as well as Cylinder head bolts that go into coolant passages.

As Rudi illustrated in his post, the use of any of these products properly and sparingly will save you from creating additional problems down the road.

Mark

Don McCombs wrote:This is what I use. It works well for me.
http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

i would think you'd want to go with don on this one period.. it's what it's made for so why fool and fumble with something that can cause headaches down the line. my .02