Gas shut off valve thread sealer?

Michael M

Michael M

Senior Member
I'm about to replace the gas shut off valve on my '31. I did a search on the forum and found one vote for sealing the threads with pipe dope, one warning not to use pipe dope, and third opinion to use thread sealer designed for gas (not sure if the the reference was to gasoline or natural gas).

May I solicit advice from the Barners?
 
I used Teflon tape on my carb inlet last week. Drove the car about two miles and it started to run poorly. Pulled the carb and found a gooey mess of dissolved Teflon tape inside the carb. Maybe there are some Teflon tapes which won't dissolve in gas and if there are, I would like to know the brand if possible.

Glen
 
The carb inlet is a compression fitting and should not have any sealant on it tape or otherwise.
 
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Lona said:
I used Teflon tape on my carb inlet last week. Drove the car about two miles and it started to run poorly. Pulled the carb and found a gooey mess of dissolved Teflon tape inside the carb. Maybe there are some Teflon tapes which won't dissolve in gas and if there are, I would like to know the brand if possible.

Glen
Click to expand...

I don't use either on fuel lines, but I've read that you need to use the yellow teflon tape for fuel lines, and not the white stuff.
 
Yellow Teflon tape is specified for natural gas use, not gasoline use. However it has been used many times by many folks (as well as with the white) so the choice on whether to use it and HOW to use it is up to you. I use neither on compression/pipe fittings. If the seal is bad (leaks), the fitting is bad (or the threads are bad-look!) and ought to be replaced. I cannot find the source, but my recollection is that Ford specified that gasoline line fittings be used ONCE. They were to be replaced if removed for any reason. I get many cycles of tightening/loosening of gas line fittings (mostly repro modern materials) by taking it easy on the tightening of clean fittings.
 
This is what I used on my new shut off valve. It is wet when applied and dries fast, so you need to get the valve screwed up and in before it does so. I think if you let it dry it would just peal off when you screwed it in. Mine has been in for 6 weeks and no leaks.

dusty

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For years I have used Otay brand pipe dope available from Ace hardware for all my fittings. It will stop leaks on anything even high pressure hydraulic fittings. It is good stuff.
 
The high-tack gasket sealant shown in Dusty's photo is the stuff I typically use in fuel line threads WHERE NEEDED. Good advice to check the threads on everything to make sure they are not damaged. I had a glass fuel bowl that had been cross threaded and seeped gas so my shop stunk of gas all the time. I finally changed it out and no more gas seeps.

I also used this when overhauling the fuel gage-it is just the right thing for that application as well to seal the cork gaskets without "permanently sealing" them. (One guy told me he used gorilla glue!)
 
The new gas eats Teflon. Avoid it.

I replaced the shutoff on my 31 Tudor last year. Used the thread sealer made for use with gasoline, says so right on the tube. It's sorta yellowish and dries hard, not flexible. To remove the fitting later, just whack it and the stuff is supposed to break free. Hasn't leaked a drop in over a year. And this is on a really picky restored car, so any leak no matter how small would be noticed and unacceptable.

Yes, the threads are tapered like NPT. However, I still used sealant just in case since you have to rotate the valve to be in the correct position, you don't necessarily get to tighten as much as you would like or you may over-rotate and the interior fuel line will not line up.
 
I have used teflon tape for many years with no problem.
You just have to be careful and not let any edges get close to the gasoline. It has to be on the top of the threads, only. It doesn't take much.
MIKE :) (mikeburch)
 
Hi Michael,

Below is a $2.99 stick made by Wm. Harvey for years.

It is sold at local hardware stores, (or order on line), for sealing "gasoline" fittings as well as others.

It can withstand 2,000 psi & 3,500 degrees F.

Unless you intend to attach a 2,300 psi air compressor to your gas tank, or heat your shut off valve cherry red with a torch, this product will work 100% of the time.

I used it for over 60 years with no failure.

Get one (1) stick -- after use, store in a zip lock bag to prevent drying out -- promise it will be the last pipe dope you need to buy for at least 10 years for your Model A & all of the plumbing "honeydo" projects around your house.

682109_front200.jpg
Print
Pipe Thread Stick


ITEM 682109 | MODEL #030005-144 by William H. Harvey


Pipe thread compound in stick form. Lubricates, seals and prevents rust and corrosion. Use pipe stick on pressures to 2,000 PSI, temperatures to 3500F for metal pipe carrying water, steam, air, ammonia, gasoline, natural gas, butane, propane, freon, petroleum oil.

Hope this helps.
 
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I have used a product called SEAL All OIL/GAS sealant with excellent results. It is a couple of dollars at Ace hardware. It comes in a small "toothpaste" tube. I made an adapter that threads on to the open end to make precise applications. It has lasted for years on my Cadillac & is a fine sealant for the fuel gauge sender unit screws etc. and tank fittings. Never needed it on my A.
 
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