Sealant for polyethylene fuel tank?

On Mar 1, 12:55 am, "Rob Turk" wrote:
I'm looking for a sealant or kit to seal brass NPT inserts into a
polyethylene tank. This is a Kitfox header tank that has developed a leak at
one of the inserts. I'm probably going to use Mogas that has ethanol
additives. Any hints, tips, thoughts?

Thanks,
Rob

ProSeal ....... or the generic =?

Take it to an RV shop and have the insert "welded" in?

wrote:
On Mar 1, 12:55 am, "Rob Turk" wrote:

I'm looking for a sealant or kit to seal brass NPT inserts into a
polyethylene tank. This is a Kitfox header tank that has developed a leak at
one of the inserts. I'm probably going to use Mogas that has ethanol
additives. Any hints, tips, thoughts?

Thanks,
Rob

Red high temperature silicon sealer. Local hardware store. Clean the
threads with alcohol and apply sealer. Lasts forever.

Dennis Fetters wrote:
wrote:
On Mar 1, 12:55 am, "Rob Turk" wrote:

I'm looking for a sealant or kit to seal brass NPT inserts into a
polyethylene tank. This is a Kitfox header tank that has developed a
leak at
one of the inserts. I'm probably going to use Mogas that has ethanol
additives. Any hints, tips, thoughts?

Thanks,
Rob

Red high temperature silicon sealer. Local hardware store. Clean the
threads with alcohol and apply sealer. Lasts forever.
I'd check the label first. Last time I looked, it specifically excluded
use near gasoline.

The kinds I've seen will swell up & shed chunks into the fuel system.

Charlie

Charlie wrote:
Dennis Fetters wrote:

wrote:

On Mar 1, 12:55 am, "Rob Turk" wrote:

I'm looking for a sealant or kit to seal brass NPT inserts into a
polyethylene tank. This is a Kitfox header tank that has developed a
leak at
one of the inserts. I'm probably going to use Mogas that has ethanol
additives. Any hints, tips, thoughts?

Thanks,
Rob


Red high temperature silicon sealer. Local hardware store. Clean the
threads with alcohol and apply sealer. Lasts forever.

I'd check the label first. Last time I looked, it specifically excluded
use near gasoline.

The kinds I've seen will swell up & shed chunks into the fuel system.

Charlie


Correct Charlie. But you never use any sealant in an amount that will
transfer product into the tank.

Problem: The fellow has a polyethylene tank, which nothing likes to
stick to anyway. Add to that, it has fuel and maybe even oil in the
tank, making it worse. Can't use a sealant that hardens, it will crack
and leak.

Solution: Use RTV in a small amount on only the threads of the insert
after cleaning both the male and female parts. Install the insert so
none of the RTV goes into the tank. Allow the gas to swell the RTV
inside the threads, which helps the seal.

Right, it has drawbacks if not used correctly, but it is the only good
solution for the situation. The only other solution would be to ream the
hole out and replace the threaded insert with a Dapco rubber bushing and
insert, better anyway. You can find them at Aircraft Spruce.

Hope this helps.

On Thu, 01 Mar 2007 20:37:38 GMT, Dennis Fetters
wrote:

wrote:
On Mar 1, 12:55 am, "Rob Turk" wrote:

I'm looking for a sealant or kit to seal brass NPT inserts into a
polyethylene tank. This is a Kitfox header tank that has developed a leak at
one of the inserts. I'm probably going to use Mogas that has ethanol
additives. Any hints, tips, thoughts?

Thanks,
Rob

Red high temperature silicon sealer. Local hardware store. Clean the
threads with alcohol and apply sealer. Lasts forever.


Except RTV is NOT gasoline resistant.

--
Posted via a free Usenet account from http://www.teranews.com

clare at snyder.on.ca wrote

Except RTV is NOT gasoline resistant.

Right.

How about some welding with a pencil torch, and some cut up strips of like
plastic?

The key is to keep the fitting hot enough so the strips of plastic stay
melted onto it, and cools and hardens after the heat is taken away, and
enough heat is also applied to the tank plastic and the strips so that they
toughly melt together.

It is a fine line, getting the tank hot enough to soften, but not melt
through.

The other option that comes to mind is a fitting that is a plate with
threads in it for the fuel line fitting, installed inside the tank and
another plate on the outside the tank, with a gasket on both sides, and
screws holding them all together. That could be done second, if the dreaded
melt-through happened around the fitting. This could be manufactured at
home, if one was a bit handy, and creative.
--
Jim in NC

Rob said his tank had developed a leak. That would mean that there had
been gasoline in the tank. I don't think anyone would suggest welding
a used metal tank, how could it be any safer with a plasic one?


Steve in Michigan

On Thu, 1 Mar 2007 22:30:32 -0500, "Morgans"
wrote:


clare at snyder.on.ca wrote

Except RTV is NOT gasoline resistant.

Right.

How about some welding with a pencil torch, and some cut up strips of like
plastic?

The key is to keep the fitting hot enough so the strips of plastic stay
melted onto it, and cools and hardens after the heat is taken away, and
enough heat is also applied to the tank plastic and the strips so that they
toughly melt together.

It is a fine line, getting the tank hot enough to soften, but not melt
through.

The other option that comes to mind is a fitting that is a plate with
threads in it for the fuel line fitting, installed inside the tank and
another plate on the outside the tank, with a gasket on both sides, and
screws holding them all together. That could be done second, if the dreaded
melt-through happened around the fitting. This could be manufactured at
home, if one was a bit handy, and creative.

"Earl" wrote in message
...
Rob said his tank had developed a leak. That would mean that there had
been gasoline in the tank. I don't think anyone would suggest welding
a used metal tank, how could it be any safer with a plasic one?


Steve in Michigan

You got it ;-) I like flying, but not *that* kind flight...

Rob

"Earl" wrote

Rob said his tank had developed a leak. That would mean that there had
been gasoline in the tank. I don't think anyone would suggest welding
a used metal tank, how could it be any safer with a plastic one?

Doh! I realized that, right after I hit send. I'm sure I would not have
done that if it were sitting there in front of me!

A soldering iron would be safe, and almost as effective at doing a little
plastic welding. It is kinda' fun, if you have ever done it before.
--
Jim in NC

On Mar 2, 12:18 pm, "Morgans" wrote:
"Earl" wrote

Rob said his tank had developed a leak. That would mean that there had
been gasoline in the tank. I don't think anyone would suggest welding
a used metal tank, how could it be any safer with a plastic one?

Doh! I realized that, right after I hit send. I'm sure I would not have
done that if it were sitting there in front of me!

When I said "welded" in my original reply I had.assumed thatmost would
take that as the "normal" method of welding plastic - with a plastic
welder that uses hot air.

Assumptions generaly BITE!

As for the idea of red silisone - don't. Been there done that. Gave
up the practice many years ago. No matter how small an amount you use
the gas wil eventually swell it up and leak through. A waste of time
and materials - IMHO