Sealing fuel fittings

What is the consensus on the thread tape versus thread sealants for fuel filter fittings and the like

I use it without any issues,even with blended ethanol fuels.I prefer the paste or gel.

I think the theory is you should not use Teflon tape to seal fuel fittings because some of it might get into the fuel system and block something. I think if you're careful with it, it's unlikely to be a problem.

That said my favorite sealant for just about any threaded connection is a product called Leak Lock. If your neighborhood marine store doesn't stock it, try a refrigeration supply company.
Highside Chemicals Inc. manufacturers Leak Lock and Leak Lock Gold.

It's safe to use with gasoline, diesel, propane and water.
About the only thing it isn't resistant to is alcohol, so don't use it on your still.

Tape will work but we prefer this.

RectorSeal® No. 5® Number 5 - RectorSeal

When I built my fuel rig, there were dozens of brass fittings. I thought about tape, but ruled it out completely. The main reason was that after quite a few test fits, tape was unreliable (and really kind of cam apart) if you needed parts to line up a certain way. You get to a point where it was too tight and then needed to back off. At that point, the tape was no longer doing it's job. Secondly was I felt the amount of tape on each fitting would be inconsistent.

I ended up just using inexpensive Thread Locker (Permatex) Blue from the auto parts store and never have a single leak. The trick was to apply it two threads back from the end of the part and 3/4 around the circumference so the excess wouldn't get into the fuel stream. Once applied, there was a pretty good working time to adjust the position of the fittings. Even the fittings that had to go back over half a turn (and almost felt loose), never leaked.

I hate to link to my fuel project twice in as many days, but we talked about this exact subject during its build that starts on Page 2 Posts #30-#37.

http://www.trawlerforum.com/forums/s6/fuel-system-upgrade-project-2798.html

Larry M said:

Tape will work but we prefer this.

RectorSeal® No. 5® Number 5 - RectorSeal

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and the choice of diesel expert Tony Athens.

I have done hundreds of fuel fittings on boats, and on generator sets.

I always use a diesel fuel rated paste type sealant.

Permatex recommends their High temperature thread sealant or thread sealant with PTFE for this use, rather than the standard blue stuff. Lots of other handy uses too. Mechanics I've dealt with have used that or the Rector seal.

I'm using Permatex w PTFE.

They use it in the shop at Harbor Marine in Everett WA.

I like to screw the fitting in until it starts to snug. Then apply the sealer just past that point. The idea being not to have any sealant where it can get into the fuel and drift along to be ingested into a fuel pump or worse. This applies to Teflon tape as well. Wrap it around but not close to the end of the threads.

Try it on old fittings where you can see through the other fitting and observe whether or not sealant or tape is exposed on the inside.

HopCar said:

I think the theory is you should not use Teflon tape to seal fuel fittings because some of it might get into the fuel system and block something...............

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That's what the experts say. It's not so much of a problem when you put it together but if you ever take the fittings apart pieces can break off and enter the fuel system.

Any fuel rated pipe dope will do just fine.

I've used everything mentioned so far at one time or another and had very good results with them all. The key is to use whatever one you pick correctly and sparingly.

Many thanks guys.

manyboats said:

I'm using Permatex w PTFE.

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That's what I use and get a tube for a few dollars at TSC.

Leak lock is the answer.
Small tube of thread sealant. That's all you need

The Permatex product does not work with propane, even though it does not mention this fact on the label. Had to redo all the propane connections with tape. Annoying.

There is also yellow teflon tape which is thicker and fuel rated.

Xsbank said:

The Permatex product does not work with propane, even though it does not mention this fact on the label. Had to redo all the propane connections with tape. Annoying.

There is also yellow teflon tape which is thicker and fuel rated.

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The yellow tape is also what you want to use on gas fittings. Like propane.

That's what I did, sorry if that wasn't clear.