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Fuel thread sealant

pa38112

Well Known Member
Is there a good recomendation for thread sealant in fuel applications? I just installed Hotel Wisky bungs in my tanks and need to plug them until I am ready for adding the tanks. I have used EZ lube on my fuel drains and I feel like it softens and leaks over time.
 
EZ turn should work for you. the fittings should be NPT pipe (tapered) threads which should seal.

-Marc
 
Be cautious with EZ turn. I recall Don Rivera saying one of the common blockages they see in FI overhauls is a bit of fuel lube, Remember, it doesn't dissolve.

I'd suggest something traditional, like brown Permatex, and make sure it's not anywhere near the tip of the fitting.
 
Here's from Section 5:

Because we cannot always fully tighten tapered thread fittings, and because even after fully tightening the fitting a small spiral leak path remains along the full length of threads, a thread sealant must be used during assembly. Sealants appropriate for use on aircraft NPT fittings are Tite-seal, Permatex #2 and Locktite 565. Do not use RTV, Teflon tape or Fuel Lube on NPT fittings.
 
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Section 5 from the -14 manual...

Because we cannot always fully tighten tapered thread fittings, and because even after fully tightening
the fitting a small spiral leak path remains along the full length of threads, a thread sealant must be
used during assembly. Sealants appropriate for use on aircraft NPT fittings areTite-seal, Permatex #2
and Locktite 565. Do not use RTV, Teflon tape or Fuel Lube on NPT fittings .
 
For another reference point, the 12iS maintenance manual recommends locktite 567 or equivalent for pipe thread sealant.
 
Be cautious with EZ turn. I recall Don Rivera saying one of the common blockages they see in FI overhauls is a bit of fuel lube, Remember, it doesn't dissolve.

I'd suggest something traditional, like brown Permatex, and make sure it's not anywhere near the tip of the fitting.

Good to know Dan, thanks! While I doubt any fuel lube could make it past my filter to clog the injectors, I'll change to something better.

-Marc
 
EZ turn should work for you. the fittings should be NPT pipe (tapered) threads which should seal.

-Marc

Ez turn or fuel lube is not a thread sealant! Locktite 565 is a sealant paste, while 567 is the same but higher temp rated (as I recall)
 
Permatex #2 is at every auto store so easy to come by....

Permatex isn’t a thread sealer either.. here’s from the manufacturer:
Suggested Applications: Valve cover gaskets, and oil pan gaskets.

Locktite 567 from Amazon, shopped to your door next day. It’s great stuff.
 
Fair nuff. But it was recc by Vans and for all my NPT fittings so far is performing flawlessly. I’ll shout out if that changes.
 
Don't always believe a label . . .

Permatex isn’t a thread sealer either.. here’s from the manufacturer:
Suggested Applications: Valve cover gaskets, and oil pan gaskets.

Locktite 567 from Amazon, shopped to your door next day. It’s great stuff.

Lets be specific about product, I have used Permatex #2 and #3 for thousands of threaded fuel fittings with success. It is dissolved/cleaned with alcohol. EZ turn is a melted polymer, a lubricant, see SDS.

I have some in-depth experience with the #3 that showed it won't overcome a poorly made NPT thread. I have 180+ threaded joints in my 175 psi compressed air manifold, and had to chase every thread and use #3. It is always pressurized and the compressor may cycle once in 3 months if not used. Stable for 30 yrs.

That said, #2-#3 is not a perfect sealant (for all situations) and have found Loctite 567 to be a superior alternative for problem joints. Certainly not the only one, but it stopped leaks for me when nothing else would.
 
Indian Head Gasket Shellac

An IA friend suggested I use INDIAN HEAD GASKET SHELLAC for fuel lines. He indicated NAPA had it...
Looking on the shelf at the local store I couldn't find it. Asked a desk clerk - they have it in the back - so be ready to have to ask for it.
It is a relatively thick brown goo. Once applied, let it set for a few minutes then install. (Of course, do not put it on the mating surfaces of the fitting.) Tighten the fitting as normal and let it set overnight.
After five years and 300 hours of EFII fuel flow, its still very secure.
 
567 is about the only thread sealer that is actually fuelproof. i know lots use permatex #2 but the label says fuel resistant, not fuelproof. if you test it in a jar of fuel you will see.
there is this sealer called ''gasoila'' that comes in a big [4-6 ounces, not like 567] container like pipe dope for water pipes. it is also fuelproof. i stopped at a new gas station site where the underground fuel system was being put in and asked a worker what they used on the pipe threads.....gasoila. i had never heard of it but you can get it online easily.
 
Gasoila - a PTFE (Teflon) based thread sealant paste. If you use auto fuel with any amount of alcohol in it, get Gasoila E-seal thread sealant. Also PTFE based, but compatible with oxygenated auto fuels. I’ve read cautions about using Teflon tape on certain installations on my airplane, but not sure about a Teflon paste.
 
i know lots use permatex #2 but the label says fuel resistant, not fuelproof. if you test it in a jar of fuel you will see.

That's kinda the point Bob. IF any of it gets loose into the fuel system, it eventually dissolves. As a thin film trapped between good NPT threads, it seals very well.
 
dan, so then is it a disadvantage that a sealer ,like 567 doesn't dissolve in fuel?

One man's opinion, but for fuel systems I want a sealer which is easy to clean out of a fitting when I take it apart, and dissolves if it escapes into the fuel flow.
 
One man's opinion, but for fuel systems I want a sealer which is easy to clean out of a fitting when I take it apart, and dissolves if it escapes into the fuel flow.

Yeah, Dan, remember that fleck we found in that fuel nozzle at OSH? There was some excess browned (previously white) sealant in the spider fittings. That showed me the perils of excess sealant in fuel especially downstream of the last filter. The sealant must have been put in the female side and pushed along.
 
that is a new take on npt thread sealer i was unaware of. i have always stayed from the tape but never knew that slightly dissolvable sealant had its advantages .very good to know.
 
The biggest take away of all this thread sealant thread is "do not" apply it or anything to any female threads and it can't get into the lines.
No more leaks if done right anyway. Art
 
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