What is the proper sealant for fuel tank fittings?

[Angela]

What sealant would you recommend to seal the threads to a sender fitting on top of my fuel tank. This is the electric fuel gauge that runs up to the flybridge. The fitting itself appears to be plastic. When I filled my aft tank, FULL, I developed a seeping fuel leak. I found the leak. It’s coming from between the threads of the gauge fitting on top of the tank. There was some white caulk-like sealant on there that is not sticking. It’s stretchy and I can smear it between my fingers and make it like an uncured caulk. I’m sure it just wasn’t the right stuff. I’ll need to re-do this with something that will seal in an oily situation. I will never be able to actually wash all the diesel off the threads of the fitting without dumping all that soap and water into my fuel tank...and I’m not going to do that.

I hope that after this past weekend’s outing that I have burned off enough fuel so that I can unscrew that fitting and get at it without creating a diesel fountain. It’s been seeping for a month, and I’ve been pumping the fuel out into a bucket as it accumulated in the “gutter” in the engine room. That “gutter” does not have access to a bilge pump, so I’m not dumping fuel overboard.

Believe it or not, you can’t smell the pooled diesel when you enter the boat; only when you open the port ER can you then smell it. That’s good!

Thanks!

 

[MikeP]

"It’s stretchy and I can smear it between my fingers and make it like an uncured caulk. I’m sure it just wasn’t the right stuff."

Sounds a bit like Boatlife, the magical "doesn't work for anything" caulk!

I'd use teflon tape or the liquid teflon pipe sealant for that purpose. That's what they are designed specifically for.

 

[Boatsb]

I would use the Teflon thread sealant and allow it to cure before putting pressure on it. Filling the tanks creates some pressure. I use this on most fuel and hydraulic fittings that require sealant and have not had a sealant failure in years.

Clean both pieces and wipe with denatured alcohol before applying it and you should be fine.

 

[Angela]

I hear ya, MikeP! And I agree. I've found that same goo-caulk on my FB hatch that appears to have been there for a long, long, long time.

Thanks, Scott. Is Teflon TAPE OK to use here? When I was looking for "liquid teflon" for the fitting on the genny's heat exchanger, I couldn't find anything that was really called that or described as that. At my local marine store, on the shelf right next to the teflon tape, I did find something in a small gray tube (like a travel size toothpaste tube) that was dark brown and thick/sticky like molassas - can't remember the name on the tube and I'm not home right now - gray tube with a red tip - called "Leak-<something>" or "Anti-Leak" or something like that. By design, it never cures hard, but the instructions were to smear it on, let is sit for about 10 minutes and then put the part together. It worked well on the H/E fittings. Do you know what that stuff is that I'm describing, and if so, is it an appropriate sealant for the fuel tank thing? I mean...that could be liquid teflon for all I know.

 

[Boatsb]

I never use tef tape on diesel. The pipe sealant is so common and available at every decent auto parts store. I use it on almost any fitting and probably go through 2-3 of the small brush cans a year.

 

[Mike36c]

Try Leak-Lock, it's what Floscan says to use for threads and it's designed for fuel.

 

[MikeP]

Ang - I want to apologize for not READING your post; I totally agree that teflon tape is NEVER to be used for a fuel fitting. For some reason, even though you clearly stated it, I was thinking "waste tank" as opposed to fuel tank when I wrote my reply.

I never Never NEVER use teflon tape on any fuel system - gas, diesel, whatever - or any oiling system.

 

[Angela]

Geez...where was my head???? I got all my "goop" mixed up. The molasses-like stuff I used on the genny's heat exchanger was "High Tack" which is what my Westerbeke manual said to use - it gave me a choice of that or liquid teflon. The gray tube of stuff is "Leak-Lock". And now, again where is my brain, I'm not sure what I used that on, but I used it on something. Maybe the zinc threads. Well...nothing is leaking on the genny.

I did confirm this evening that we girls burned enough fuel over the weekend to stop the seeping - it was a "three-Mermaid" weekend on Sanctuary. LOL Now, I can fix the thing and then clean up the mess. I'll look for some liquid teflon and keep some of that on hand, too. The guys at the auto parts store had never heard of it. I tried Auto Zone, Auto Source (or whatever it's called), Home Depot, and my marine place. The marine place had the Leak-Lock.

 

[Angela]

Oh, Mike....I think I've done enough waste tank fitting and crap, literally, to last me a lifetime. I replumbed this entire boat except for the fittings themselves on the second holding tank, and that on has Ed's name written all over it! Time to pass the torch on that stuff.

 

[Boatsb]

http://www.permatex.com/products/automotive/thread_compounds/a_thread_sealants.htm


What auto parts store did you go to?

maybe it's time to find a new one.

 

[Angela]

http://www.permatex.com/products/automotive/thread_compounds/a_thread_sealants.htm


What auto parts store did you go to?

maybe it's time to find a new one.

Everytime I go to any autoparts store around here, it's a nightmare, no matter which one. I will say, however, the guys a Napa are better than others. Without a "what's your make, model, and year, please", they can't find squat. I was looking for a radiator cleaner/flush and the girl at the counter couldn't even point me in the right direction - I had forgotten to take my glasses - she kept picking up stuff like fuel additive and asking me if that was it - this was after she wanted to look it up in the computer with the make, model, and year. Oh, just remembered...she first picked up a can of CRC electronic cleaner, handed it to me and said, "this should clean it, shouldn't it?" That's when I knew she didn't even know what a radiator was. Next, I wanted a 14# radiator cap, but without a make, model and year, they couldn't tell me if they had one. When I tell them 1980 Detroit, 8v92, they actually try to put that in their computer only to tell me that they can't find my vehicle. Yes, I know the DDs take the 7# cap - the genny takes a 14#, but I thought they could spell Detroit before they could spell Westerbeke, and I was just messing with them because their question was so stupid. LOL I always come home from the autoparts store with a "you're not going to believe this $hit..." story. My quest for a torque wrench was one of them.

Scott, I remember seeing all of those Permatex products, and I asked at each place whether those were considered "liquid teflon" and no one knew. Well, I'm smarter today than I was yesterday because now I know.

 

[Trojan]

It's not that you can't use the Teflon tape on gas or oil. It's that if not properly used you can have particles of tape being cutoff by the threads and these particles could get into areas where you don't want them. Most people use too much tape to start with. You are not to let the tape extend over the end of the fitting your trying to seal. If you have not used a lot of Teflon tape than you are best to use the liquid paste type Teflon and not have worry. Just don't get carried away with the more paste is better or the same thing could happen. A little goes a long way.

BILL

 

[rsmith]

What sealant would you recommend to seal the threads to a sender fitting on top of my fuel tank. This is the electric fuel gauge that runs up to the flybridge. The fitting itself appears to be plastic. When I filled my aft tank, FULL, I developed a seeping fuel leak. I found the leak. It’s coming from between the threads of the gauge fitting on top of the tank. There was some white caulk-like sealant on there that is not sticking. It’s stretchy and I can smear it between my fingers and make it like an uncured caulk. I’m sure it just wasn’t the right stuff. I’ll need to re-do this with something that will seal in an oily situation. I will never be able to actually wash all the diesel off the threads of the fitting without dumping all that soap and water into my fuel tank...and I’m not going to do that.

I hope that after this past weekend’s outing that I have burned off enough fuel so that I can unscrew that fitting and get at it without creating a diesel fountain. It’s been seeping for a month, and I’ve been pumping the fuel out into a bucket as it accumulated in the “gutter” in the engine room. That “gutter” does not have access to a bilge pump, so I’m not dumping fuel overboard.

Believe it or not, you can’t smell the pooled diesel when you enter the boat; only when you open the port ER can you then smell it. That’s good!

Thanks!

This is the best stuff there is. Used in sealing aircraft fuel systems. Resistant to damn near anything.

http://www.aircraftspruce.com/catalog/eppages/titesealit.php

 

[spartonboat1]

Ang - I want to apologize for not READING your post; I totally agree that teflon tape is NEVER to be used for a fuel fitting. For some reason, even though you clearly stated it, I was thinking "waste tank" as opposed to fuel tank when I wrote my reply.

I never Never NEVER use teflon tape on any fuel system - gas, diesel, whatever - or any oiling system.

I used to use Teflon Tape "when I was younger" decades ago. I no longer use it for anything, since I understand there may be long term galvanic corrosion issues. Long term can mean 10-20-30 years, not just "five years". I now use the best pipe near-paste-type dope I can find, usually found in a yellow plastic tube, for non-industrial (gallons) applications. Have had no short term issues.

Otherwise, I would be going with floscan's recommendation or better yet, the post
"This is the best stuff there is. Used in sealing aircraft fuel systems. Resistant to damn near anything.

http://www.aircraftspruce.com/catalo...titesealit.php"

FWIW, for "make it on the fly" gaskets, I now swear by Permatex "Ultra Copper Maximum Temperature RTV Silicon" type stuff, which of course can also be used for high temp apps. Have used it in a pinch several times for water sealing, such as through hulls and an Inspection Port (coated over the new cork gasket) on the DD, without issue. Have not waited on cure times, again, no issue. Comes apart well and peels off well.

I would also be interested if YtsManBill weighed in.

 

[davidwigler]

Tony Athens at Seaboard Marine recommended and sold me a can of Rectorseal #5 for installling fittings on the new SeaMax fuel filters. It worked fine. It's UL rated for gasoline and petroleum oils.