Popping a tank ding by freezing water filled

when I was in my early teens (70's) Friends often placed their dinged tanks in a freezer, filled with water to pop out a ding, I have 2 dings in my 85 XJ600, anybody ever tried this?... I'm going to soon.... unless someone has other news?

My largest ding is a dish on top of the tank, looks like it would pop fairly easy with pressure from behind, the other ding is on the side and is quite sharp... the paint is quite good especially considering the bike is 25yrs and the last owner neglected it ... I'm hoping to get it back to close to original ... A good spray painter should be able to match the paint if it cracked after the fix.

 

I've seen it done with headers and two-smoke expansion chambers. I used the torch and inflate with compressed air method on my own headers (not cosmetically friendly)

I'd be mighty worried about doing it on a gas tank. Could easily end up cracking the seams.

 

Just a little bit of water left in the Manifold of a Cast Iron V-8 will crack the block if it hard freezes.

The seams on you Fuel Tank are going to be no problem for the Ice to split wide open.

The BEST way to Pull-out a Dent ... is to rent a Copper Rivet Spot Welder Kit and buy a Box of Rivets.
Grind off the Paint.
Put the Rivets along the area that you need to pull-out.
work from the OUTSIDE --> IN.
Reduce the damaged area to what can be treated with Body Repair Materials.

Grind-off the Rivets.
MarGlas the area to be repaired.
Shape and sand the MarGlass.
Get a near-finished product.
Skim-on Bondo.
Sand the Bondo to the "Finished" shape.
Let somebody else eyeball the work and mark imperfections.
Final Bondo and Finishing.
Prime, Paint and clear.

 

1. Go by a body shop and see if any of the guys there have some of the old "shepard's hook " body tools or cut out your own to fit and weld a washer on the end that will go through the filler hole. put a large gob of silcone on the washer and form it with seran wrap. pop the dent.
2. Find a mean suction cup and use a slide hammer.

 

Gaining access to the rear of the damage to hammer-out the dent os limited by thee tanks design.

The hump that goes-over the frame is right-up close to the filler cap.
The underside is sealed unless the bike has a sending unit.

If you want to "Pound-out" the dent.
Study the geometry.
Drill --> CLEAN Holes opposite the damage.
Use Hard-wood Dowels with the ends sanded round.

After the dent is pushed-out.
Grind the area around the access hole and braze or lead-load a patch.
Welding presents a challenge.
The underside of the tank is very narrow gauge sheet metal.
It "Burns-through" easily; puddling the weld around the patch takes a good deal of experience in welding.

 

An additional caution when considering welding a tank. The tank will need to either be boiled out or inerted to prevent fuel fumes from igniting when you heat that sucker up. Fill the tank with exhaust or other inert gas to prevent an explosion.

 

To "expand" on Robert's warning about gas fumes...drop two small pieces of dry ice into the two sides of the tank.. CO2 will drive out gas fumes. After the dry ice is eliminated, there will be nothing in the tank except CO2. No water, no fuss.

Personally, I would swish isopropyl alcohol in the tank to remove any moisture, then swish diesel fuel & 10% marvel mystry oil to oil wet the surfaces. When you are ready to place the tank in-service, swish 3x with gas to remove diesel-mix.

 

Wow!
I thought you were going to include stuffing a Canary's head into the Filler Neck of the Tank and seeing if the bird croaks.

After you swish 3x with gas to remove the diesel mix, ... do you do the Dry Ice Trick again?

By the time you get ready to strike an arc on a Fuel Tank that has been off the bike, drained, drilled, undented (sic), glassed, sanded, shaped, Bondo'ed, sanded again and again, left sitting while you get a coke, take a leak, quit for the day, take the weekend off, return to continue sanding and shaping the filler ...

Blow it out with compresses air or the hose of a vacuum cleaner hooked-up to it's back-side.
10 minutes.

 

just put a handful of dry ice in it and close the lid, that should test your vent and pop the dent at the same time

 

Darn RickoMatic...you take all the science and anal character out of the sport!!!!!

 

this one gets my vote!!!


honestly, i would never try the ice method. i have seen what ice will do to a large diesel engine block, radiators, PIPES IN A HOUSE, your fuel tank is no match.

post up pics of the dent and maybe we all can fine tune our advise to better suit the dent at hand.

 

I pulled one out with $2 suction cup from Ace hardware. May not work on your dents.

 

I remember seeing an episode of Monster Garage where a fuel tank hadn't been welded together right, and was leaking profusely. The poor sap who did the work was saying it would have to be purged with Argon before he could try and patch the welds.

 

Hey polock, plug the blowgun from the air compressor into the fuel line from the petcock. Saves a trip to the store for the dry ice.

I also made a special fitting that plugs the shop air into a soda bottle for that other use for dry ice. 85-100psi does the trick for a 2 liter.

Folks, we don't recommend this. (=

 

Hey...been there!!
Did that with a 2 liter in front of the house with my young boys. The bottle went EVERYWHERE.

We laughed hard!!! Got creative and glued fins in the bottle to straighten er out...the G-forces at take off ripped 2/3 fins off. But it went straight for a few hundred feet!!!!!

 

If your dents are small I hear that taking a hair dryer (or a heat gun) and heating up the dent then putting the ice cube on it works to pop out smaller dents.

In theory it works warm the metal so it expands then cool it fast so it contracts and pops the dent right out.


This is what I will be trying for any dent on my fuel tank when I paint it.

 

dont let the paint get too hot!

 

i saw, and tried the hair dryer, then you take keyboard duster, upside down, and use it, though i think my dent was too big and on too thick of metal

 

Took the gauge out and used a suitable piece of dowel, quite large, about 1 and a half inches across to push the dent out, the other dent will be pulled out when I get the mig out and weld a washer to it (tank will be filled with water after thorough washing) and pulled out.

cheers.
J