Black Widow - Tank Repair

AMCGUY Fri Jun 05, 2015 7:00 pm

I've got a Cox Black Widow that a previous owner had drilled a hole in the tank. Can this be repaired?...JB Weld...or something else? Any advice or tips? Thanks, Darron

GallopingGhostler Fri Jun 05, 2015 8:14 pm

If hole is large enough to pass a fuel line through because previous owner wanted to use an external tank, required thickness of JB Weld to bridge might take away some fuel capacity, I'd be concerned over failure over time due to high frequency vibrations but you've got nothing to lose if you try.

Cox International has replacement aluminum tanks:

Without stunt tank fill and vent tubes (use Babe Bee style back with nipples):
$13.95 US http://coxengines.ca/8cc-aluminum-fuel-tank-black.html
Plastic one at $6.95 is cheapest.

Stunt tank version:
$16.95 US http://coxengines.ca/8cc-aluminum-fuel-tank-for-cox-049-black-widow-engine.html

Required flanged reed retainer for use with aluminum tanks:
$1.95 US http://coxengines.ca/cox-.049-reed-retainer-flanged.html

Required flanged reed retainer for use with plastic tank:
$1.95 US http://coxengines.ca/cox-.049-reed-retainer-3.html

**RknRusty** Fri Jun 05, 2015 8:29 pm

If you aren't concerned with looks, you can take a 3/8"piece of wide fuel tube and jam it in the hole. Plug it with an epoxy treated bit of dowel that expands it even tighter. Some of the reddish pink line from Brodak is incredibly grippy and would stay in place. Smooth and radius the edges of the hole with fine sandpaper first. It won't affect the capacity in any measureable way.

Rusty's Repository of Redneck Repairs.

Marleysky Fri Jun 05, 2015 8:47 pm

PLUS 1 for RUSTYs redneck repair

Or try a NEW Tank http://www.exmodelengines.com/cox-.049-fuel-tank-bowl-8cc-black-widow.html

AMCGUY Fri Jun 05, 2015 9:55 pm

Thanks for the ideas and links. Darron

**Cribbs74** Fri Jun 05, 2015 10:40 pm

Of course a new tank as suggested is the best solution.

You could plug the hole with a bolt, nut, a couple of rubber washers and two flat washers. Depending on where the hole is.

Really there are a bunch of things you could do to make the tank work. Heck you could even TIG weld it if you were so inclined.

Ron

getback Sat Jun 06, 2015 8:09 am

Clean it up good put some tape on the outside and JB it from the inside ...... take tape off if black use perma - marker to cover . Fly that Bird !! Very Happy

**Cribbs74** Sat Jun 06, 2015 1:14 pm

JB weld and Nitro do not work well together. I have used JB on leaky tank vent and it just gets eaten away.

roddie Sat Jun 06, 2015 3:05 pm

Cribbs74 wrote:Of course a new tank as suggested is the best solution.

You could plug the hole with a bolt, nut, a couple of rubber washers and two flat washers. Depending on where the hole is.

Really there are a bunch of things you could do to make the tank work. Heck you could even TIG weld it if you were so inclined.

Ron

I save scrap inner-tube rubber from bicycle tires. It's handy for all sorts of things. Depending on the hole size to be plugged.. cut two oversize discs.. and pierce them in the center with an awl for the screw to pass through snugly. Back these up as Ron mentioned; with small steel flat-washers inside and out.. and install a short (1/4" to 5/16" length) machine-screw from the inside-out.. with a lock-nut on the outside. Probably a 4-40 size might work.

Here's an example of a 4-40 machine screw plug (I made one to seal a 1/4" dia. hole in one of my Bee's tanks)

Black Widow - Tank Repair Dsc02712

**RknRusty** Sat Jun 06, 2015 3:20 pm

First we have:

RknRusty wrote:If you aren't concerned with looks...

Rusty's Repository of Redneck Repairs.

And now for Roddie's less redneck way to do it.

roddie wrote:I save scrap inner-tube rubber from bicycle tires. It's handy for all sorts of things. Depending on the hole size to be plugged.. cut two oversize discs.. and pierce them in the center with an awl for the screw to pass through snugly. Back these up as Ron mentioned; with small steel flat-washers inside and out.. and install a short (1/4" to 5/16" length) machine-screw from the inside-out.. with a lock-nut on the outside. Probably a 4-40 size might work.

I guess mine would be considered innovative in the field. Like if it took a stray bullet from a nearby range at fort Jackson, you could have it back in the air pdq.
lol!

TDbandit Sat Jun 06, 2015 5:49 pm

If the hole is not huge you could use a pop rivet, put some sealant around the hole or even some jb weld install the pop rivet and then use a dab of jb weld to plug the core of the rivet just make sure the hole is not to close toy the seal (backplate) end of the tank. The repair looks like a gas cap lol (Bandit)

GallopingGhostler Sat Jun 06, 2015 6:13 pm

A modification to Ron's reply is replace the 2 rubber washers with a servo grommet of suitable size. Very Happy

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