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Author Topic:   Fuel Line Fittings: Sealing Threaded Connections and Hose Barbs
Raaaaay posted 08-17-2010 11:39 AM ET (US)   Profile for Raaaaay   Send Email to Raaaaay  
When installing a new fuel tank and all fittings and hoses, I have read about sealing the brass fittings [and] threads with Permatex. Do I also put Permatex on the hoses where they push onto the barbed brass fittings?

Any other suggestions for this discussion would be appreciated!

contender posted 08-17-2010 12:29 PM ET (US)     Profile for contender  Send Email to contender     
On a brass threaded fittings I use [Teflon] tape, some people use [Loctite]. I do not use any [sealant] on [hose] barb connections. However, I do have a special tool for stainless steel crimps and clamps that I use on the barb fittings. I also carry a bunch of plastic ties on board just in case.
tom976 posted 08-17-2010 12:32 PM ET (US)     Profile for tom976  Send Email to tom976     
Permatex makes different sealants. Getting the right one is the key. Whatever it is, make sure to get the stuff designed to be in oil and gas.

As for putting a hose over a barbed connector, sealant goes on there. A quality stainless hose clamp goes on that. Don't be cheap on this stuff, as you will not want to deal with this down the road.

Raaaaay posted 08-17-2010 07:31 PM ET (US)     Profile for Raaaaay  Send Email to Raaaaay     
I have read of people using Permatex Pipe Joint Compound with success, so I will use that on the brass threaded fittings.

On the USCG vent hose I will just use stainless steel clamps. I just dont want any leaks as the vent hose is under the large floor cover and hatch, and, once I get this screwed down and sealed, I don't EVER want to have a problem with leaks.

Bella con23 posted 08-17-2010 07:47 PM ET (US)     Profile for Bella con23  Send Email to Bella con23     
It is important to remember that one can over tighten a fitting using a sealant. The sealant has a lubricating effect that can cause female fittings to split when over tightening.
Tom W Clark posted 08-17-2010 08:55 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Permatex is a brand, not a product.

Use Permatex Pipe Joint Compound on threaded fuel fittings.

Do not use Permatex Pipe Joint Compound on barbed fittings.

Raaaaay posted 08-18-2010 12:56 AM ET (US)     Profile for Raaaaay  Send Email to Raaaaay     
I don't think there was anything in the discussion that commented on Permatex being a brand or a product. I did specify on my second posting that Permatex Pipe Joint Compound as the product I would use for the threaded fittings. Tom--that was based on other posts I had seen from you. I just started off the discussion using the brand reference in the general sense.

The real point of this discussion was asking if something was to be used on the rubber hose to brass barb connection, or, is the hose just always clamped

Jefecinco posted 08-18-2010 09:56 AM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
Yes, just clamped.


dino54904 posted 08-18-2010 10:00 AM ET (US)     Profile for dino54904  Send Email to dino54904     
Engine manufacturers--Mercury, Volvo and MTU in my experience--advise AGAINST using Teflon tape on fuel fittings. There is a chance that if you use a bit too much tape it could extend beyond the end of the fitting, eventually come off and plug the downstream line or the filter. They have likely discovered this through experience.
tom976 posted 08-18-2010 10:11 AM ET (US)     Profile for tom976  Send Email to tom976     
To make sure you get a decent clamp, run a magnet over it. Some stainless clamps are mostly stainless with some regular steel on there. Since this area you don't want to go near for the next few years, just make sure you do that.

Some stainless will be slightly magnetic (depending on quality and composition) but don't panic about that, if it stick hard like on steel that's a problem.


Raaaaay posted 08-18-2010 03:16 PM ET (US)     Profile for Raaaaay  Send Email to Raaaaay     
Thanks for the input on this topic. I just wanted to make sure that everything was done totally correct before the deck lid gets screwed down and sealed. I hope I will never have to deal with it over the life of my ownership of the boat.
Tohsgib posted 08-18-2010 03:20 PM ET (US)     Profile for Tohsgib  Send Email to Tohsgib     
I have never used any kind of brand or product when doing this. I pressure test for leaks if I can. Compounds can get real nasty when mixed with gas; better off dry in my opinion.
jimh posted 08-18-2010 05:48 PM ET (US)     Profile for jimh  Send Email to jimh     
As Tom mentions, "Permatex" is not a specific product. They make products for

--cyanoacrylate, general purpose
--cyanoacrylate, rubber toughened
--cyanoacrylate, surface insensitive
--gasketing, Right Stuff
--gasketing, RTV
--gasketing, anaerobic
--gasketing, sealants
--retaining compounds
--threadlockers, liquid
--threadlockers, gel
--thread sealants
--hand cleaners
--specialty adhesive

When one says "I have read about sealing the brass fittings [and] threads with Permatex," it is a bit ambiguous exactly what product is being referenced.

I recently installed some threaded brass fittings and the instructions recommended using a thread sealant with PTFE. I just used the local Ace Hardware store brand, not the Permatex brand: family=Thread%20Sealant%20with%20PTFE

I cannot recall any mention of any compound being applied to a hose barb fitting, other than perhaps some water or spit to help install the hose onto the barb. Alcohol will also aid in sliding a hose onto a hose barb--you can apply the alcohol to the rubber hose, or, if the alcohol is in a potable form, consume some of it to help the project move toward completion.

Raaaaay posted 08-18-2010 07:29 PM ET (US)     Profile for Raaaaay  Send Email to Raaaaay     
OK, point taken. Thanks again
Raaaaay posted 08-18-2010 07:40 PM ET (US)     Profile for Raaaaay  Send Email to Raaaaay     
Ah, I just got your last suggestion. Do you think a Sam Adams would help? I know putting this Classic Outrage back together is definitely dragging on but good thing I can go boating year round out here.
Loafer posted 08-20-2010 02:21 PM ET (US)     Profile for Loafer  Send Email to Loafer     
Sam Adams works well on the hose barbs. However, they make several products, you must be more specific:
Boston Lager
Summer Ale
Heffelwhatnot (no one uses that one)
Latitude 48
Old Fezziwig (cold weather formulation)
and about a dozen others. My preferance is Latitude 48, but it is not always available.

On a more serious (but less important) note: you are more likely to get leakage through the fuel level sender within its totally crappy little box set in the top of the totally crappy aluminum fuel tank under the totally crappy and not water proof, water resistant or even water repellant cover that you will never, ever for the rest of your life get to seal so forget it... 'cause the water will come in the totally crappy little drain (?) hole in the top of the tank cavity anyway. Ok, ok... no shouting, take meds... I haven't had my Latitude 48 ('ludes) yet today.

This topic will be the subject of a long, illustrated, informative and (I promise) not whiny post here as soon as I figure out what the solution will be.

Loafer (as opposed to Topsider, say)

Raaaaay posted 08-20-2010 05:47 PM ET (US)     Profile for Raaaaay  Send Email to Raaaaay     
Boston Red Brick is my favorite "product" but can only be acquired in Boston, so here on the west coast I may have to resort to my second choice.

Yes, I am in the process of installing a new aluminum tank in my restored Outrage and will have the fun of trying to seal up the crappy cover and all the little protrusions that go through said cover. I think the hardest thing to seal will be where the vent hose routes through the deck into the tank cavity. Is there a better way to seal that area? I should start a new discussion on that point.

Loafer posted 08-21-2010 03:25 PM ET (US)     Profile for Loafer  Send Email to Loafer     
That's the point... you can't seal it. it's in the bottom of a boat and boat bottoms get wet. I'm sure even America's Cup racers carry some bilge... Hell, the Space Shuttles probably carried some bilge. So design around the certainty of water getting in there and you won't be wrong.

I think that was the original intent of the pour-foam around the tank, to displace the water to the top and let it run out the drain hole in the back. However, the water gets everywhere eventually, inculding the inside of your fuel tank. Just boat-kismet.

Therefore, (in my ever so humble opinion) there is no use trying to seal the top down, especially the little channel that the vent lines run through, or the holes where the fill pipe and draw tube come through the cover. But make damgoodn'sure that the fuel gauge sender is sealed, that's where the water's gonna run in. Permatex (gasket sealent, that is... the black crud that takes a week to rub off your finger tips) for the sender, and some nice hoppy Anchor Steam for the tank installer (west coast stuff, anyway).

Good luck,


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