The Stovebolt Site Forums The Shop Area General Truck Talk Sweating a Gas Tank Filler Neck

Alright, I'm in the middle of de-rusting my 54's gas tank, and I had to de-sweat the filler neck to do it. Pretty soon it will be ready to go back on, and I now realize that I've never even sweat pipe before. I have a MAPP Gas torch, and a Propane torch. What type of solder do I need to use? Are there different types of flux? It would really suck to get this tank completely de-rusted and then not be able to get the filler neck back on. HELP!

It would be really awesome if somebody could post a link to an instructional video or something similiar.


Thanks,

if you want to insure it's right, take it to a rad shop and let them do it .... otherwise your MAPP might work, using 50-50 plumping solder and the flux for it

Bill

Every shop I called wants $60-$80 bucks just to sweat the neck back on, because it's a gas tank, and they would have to de-fume it. I'm OK with just filling the darn thing w/ water and flaming it out, then sweating the neck. That's how I got it off in the first place. I've just never tried sweating anything before.

BTW...I'm really glad I filled it with water before I de-sweated the neck. there was probably only a gallon's worth of air space in there and the sucker sounded like it was going to take off....WOOOOSH!

Bryan

An excellent high strength alternative if you can purchase some is to use a silver solder it flows easy and ususally has the flux on the rod so is easy to apply. Do you have a friend who is a welder or plumber that could give you a few minutes of instruction "teach a man to fish" and all that you know.

Good move filling the tank with water.

I don't solder professionally, but I have built a few computers, stereos, and fixed a couple radiators.

Most of your work is already, you should have a good tinning on the parts. I'd start by cleaning the excess solder off. Heat the parts up and wipe with an old rag. Cleaning the parts may let you get it started enough so you can wiggle it in with heat. Put a light coat of paste flux on and heat. Don't over heat you need just enough to keep the solder shinny. If your really good the solder will follow the flame. You may want to add just a touch more solder, you won't need much.

LG

I worked in a shop with an old time Chevy mechanic. If I remember correctly, he like using acid core solder for radiator necks. I would be willing to guess that it would work as equally well on a fuel tank. If you go the plumbers solder route, a HVAC technician showed me once that he likes brazing a joint with Silphos and then going over it with plumbers solder. -Just a suggestion.

On solding the tank.My self I run a hose off a running car's exhuast pipe to the tank to be soldered.Wait about 10 minutes with the hose still in the tank running.Then your ready to solder.No oxygen in the tank now,No boom and no water to bother with down the road.Old man's tricks.

from an article i wrote about cable making
this solder is great buy the small coil at $ 21.00 from a welder supply

The one item I have not mentioned yet is probably the most important, the solder. We have all used in a pinch not knowing any better the old standby solder readily found in our garages. Electrical 60/40 Tin-Antimony-Lead solder, plumbers solder made of 50/50 silver leadless or 60/40 tin-lead solder. Silver, Zinc, Indium and Cadmium are also used in combinations in the making of various solders; each has their pluses and minuses. Most of these are flux core solders but that does not mean you can not add your usual paste-flux to this process. These types of solders have a relatively low tensile strength of 4500-6000 psi. The MG product has 3x the tensile strength as these electrical types. Now just because the above plumbers silver
leadless solder says silver, does not mean that it contains a good amount of silver content, maybe 6-9 % at most. Silver solder is by far the best way to join the fittings in this case, inner cables to brass fittings. There are many silver solders on the market, used for a multitude of purposes, most with heat ranges around 900-1400 F. degrees working temperatures. This depends on content and percentages of alloy material. This is too high for our use when cable making. Infact it is best NOT to use an open flame- torch on inner cables, but a very good soldering iron is needed. Some of you may have your soldering pots and used them for decades, and they work.
But silver solder does come in a lower temperature heat range for gas type torches without oxygen and iron use. This product‘s working temperature is 430 degrees, perfect for soldering iron use. I prefer this product MG120, also known as MG120A. These MG products use a flux core and cleaning agent for the preparation of bonding. The MG120A has a syringe applicator for the cleaning agent whereas the MG120 is a bottle. It is available at welding supply stores. This stuff IS the Bee’s knees.
The key to a strong union is wetting and capillary attraction. Wetting is the ability of the molten solder to coat the strands surface. Capillary attraction is its ability to flow or wick. I prefer to ‘’tin’’ the inner cable end after I have slid my end fitting on to the inner cable first. This allows you to ‘’work over’’ /mushroom or flair the multiple ends more easily to prevent the dreaded pull-out. Pull the inner cable back to the fitting and solder. Trim or file the fittings when done.
Remember to lubricate all your non Teflon lined cables once a year by buying one of those simple spray type lubricators available at any good local m/c shop. I use a spray can of white lithium grease. These devices clamp over the outer cable end, have a small rubber hole built in and the grease squirts inside, down the cable housing through to the end. If you use a junction box with a single throttle cable to twin cables make sure you protect that junction from dirt and debris, clean and lube with light grease once a season along with all of your other cables.
Remember what Owsley Bear says ….… ‘‘They love to get out and play in the sunshine.’’

>> made by:
Messer Company - MG Welding Products
N94W 1455 Garwin Mace Drive
Menomonee Falls, WI. 53051 USA
(262) 255-5520 -- (262) 555-5542 fax#
Hardness 15 10 kg/ mm2 approx 15,000 psi
Melting point 430 degrees F 221 degrees C
Available in :: 1/16’’, 3/32’’, 1/8’’ >>>> use 1/16’’ for cables

From what I understand....after you flux the surfaces you should only heat it enough to make the flux smoke, not burn....

So, since the parts I'm soldering are fairly thick, maybe I should heat them a little, apply some flux, heat them some more until the flux starts to smoke, then put the filler neck into position on the tank and continue to heat as I work around the edge of the filler neck with the solder.

Sound good?

Your on the right track. Try and heat it up evenly. It's not like soldering the end of a wire, you've got a bit of metal to heat up. At some point your going to have to heat both parts at the same time. When your done you want the solder to be shinny. If the solder is dull on the surface it's usually an indication of a cold joint not enough heat.

LG

Years ago I was hired as a maintenance man in a hotel that had shut down an annex in the winter. They didn't drain the plumbing of water, and had hundreds of breaks. Needless to say I got good at sweating copper fittings together in a hurry. A couple of pointers. Heat the fitting and flux and touch the solder to the metal and let it flow into the joint. Also if you need to work on a closed system flood the area with co2 if you have it or get a couple of pounds of dry ice at the grocery store and put it into the tank. No oxugen no WHOOSH or worse. You can also flood the area with gas out of a MIG bottle. Expensive but effective. I once made a BBQ pit out of a 6 X 2 foot propane tank. I filled the tank with co2 and let it set for a couple of days. I refilled it and cut the door out of the tank with a demo saw. Lots of sparks off the saw, but not a thing from the propane tank. Once I had the opening cut I took a propane weed burner and hosed the inside down with flame. I never got even a little reaction. I still have the BBQ pit to this very day.

actually i welded mine as shown

http://s67.photobucket.com/albums/h...&current=3100lockinghoodlatch-05.jpg
http://s67.photobucket.com/albums/h298/1951otter/?action=view&current=0465700-R1-035-16.jpg

as far as the tank goes [you did say filler neck .... not tank] flood it w/ water. does the same as CO2 or argon gas [tig/mig]

I got it sweated on last night. Took longer than I thought, and took three hands at one point. (Thanks Wife!) but it's on. I had a leak the first time I pressure tested it, (blowing as hard as I could into the neck.. real professional...) but, that didn't take long to fix. The acid core solder I used worked well as far as I know, first time sweating and all. Thanks for all the help and advice guys, this forum has been a wealth of knowledge for someone who was born over 30 years AFTER my truck was built.