Fuel System: Filler Tube Solder Joint Fail...UGH!

[jclary]

I had already commented, in another thread, about gas tank leaks, that I was going to attempt to diagnose where my tank was leaking. Today, in-spite of spending most of the morning, filling out forms for the Veterans Administration (redundantly chasing down information they have on file...again and again). So far, I have not had any problems with high blood pressure, but...attempting to negotiate this cumbersome bureaucratic maze might do me in.

Anyway, I finally got to this long overdue task. Once I had the seat out, removed the access plate to the gas gauge sending unit, I performed a "soapy water test" on the sending unit. Using a small amount of soapy water brushed over the unit, and blowing in the tank produced some small bubbles. However, I sensed that the amount of gas that spilled out on the ground, the last time I filled the truck, couldn't have come from that area.

I decided to investigate a little further, by removing the filler tube and the rubber connector between the tank filler tube and the piece of tube that holds the gas cap. Well...this is what I discovered.

This is a relatively low mileage never "off-frame" truck. The good news is that the tank looks new inside. The bad news is that I'm gonna have to remove it to repair it. Another thing, I noticed, is how the tube position is not centered in the opening of the truck floor. I wonder if that could have caused stress on the tank tube, vibrating over the years, and causing the soldered joint to fail.

I have always been good at soldering. 'Cept my soldering has always been strictly copper/brass connections. Not steel, and certainly in no gasoline container. Unless some of you folks have experience with a sure fire (OH MY...perhaps I should stay away from that word!)...fail proof adhesive/joint compound...I suppose I'll have to find someone to re-solder this thing.

Anybody else experienced this kind of failure on C-cab trucks? Most of the gas tank problems we discuss seem to involve rust, or accidents.

[63 R2 Hawk]

I don't think you can find any kind of flameless soldering iron with enough heat/mass to resolder this and it's hard to find any "old school" auto repair guys who know how to solder it SAFELY with a torch. If you google the subject you will find lots of information, eg http://weldingweb.com/showthread.php...as-tank-safely. I have seen guys successfully torch solder & braze fuel tanks by putting a bunch of dry ice in the tank to generate CO2 and keep it from exploding, but you have to know what you're doing..!!!

[larkregal62]

John, I have used JB weld on Gas tanks in the past--ISs that a possible alternative for you??

[Alan]

Take it to a radiator shop and have them tank it for you. If they will not repair it for you, fill it near full of water and use a propane or Map gas torch to re solder it.

[doofus]

John, Alan has the best suggestion. If still having trouble with VA go to local county Veterans office they can be a real God send. are you a viet vet from the early '60's like me if so make sure they check you for diabetes. anyone serving in that time period gets a special going over! Doofus

[altair]

What about old school blow torch and heating iron (copper). Heat the iron (copper) away from the vapors with the torch and transfer the heat. Buff the remaining solder to remove as much oxide as possible, flux and re heat should take with out a problem. There are a variety of iron sizes out there you can find them at swap meets or second hand/antique stores. I have a variety that I have picked up over the years the biggest one is about 1.5 lbs, that will transfer a lot of heat.

[TrickyRick]

I used to fix gas tanks with a big giant electric iron with gas in them!

[52 Ragtop]

I'll agree with Alan, Take it to a radiator shop, they will boil it out, fill it with water, and solder it up. no fuss, no mess and best of all NO explosion! Do it right, and forget about it.
If you think there could have been an alignment problem, put it in and mark it where you think it should be. Then go to the radiator shop.

Jim

[jclary]

I appreciate all the comments, so far. As to soldering, I would love to have at it myself. But, only if I had some "old-school" experienced expert looking over my shoulder guiding me. Back when I was in Air Force tech school, I did so well soldering, that I was asked to assist those having difficulty. Years later, when I decided to go into plumbing as a business to earn extra income, I took a course at a local tech school. Again, I was pressed into service as a teacher's aid helping the young kids just out of high school.

I have confidence in my ability to handle the tools, where to apply heat, and the process. It is the "gasoline" part that I'm not experienced with, and don't intend to test how "lucky" I can be. I didn't get this old by throwing caution to the wind. I have read the other threads on this subject, and there are a number of good suggestions regarding adhesive chemicals. In my career, I have sold JB Weld, Devcon, Loctite products, and have participated in developing some fairly sophisticated precise dispensing equipment for industrial applications. Problem is, I've been "out of the loop" for years now. Even when I was in that business, these products were not the major focus of my sales and application efforts. Most of my experience was in clean sanitary production environments, and certainly not involving gasoline.

I like the idea of JB Weld, because it is a tried and true product. In this thread by Jeff_h http://forum.studebakerdriversclub.c...B-weld...forum member 5brown1 recommends the product "Seal-All." Here is the link to that http://www.eclecticproducts.com/sealall.htm. What I like about the Seal-All product, is that it seems to be thin enough to "wick" into small voids, works in the presence of gasoline and alcohol. It has a decent cure time, and accepts subsequent applications without having to re-work the joint.

Since the "fit" of the fill tube and the opening in the tank is a near "press" fit...I'm tempted to use the Seal-all product. I'm thinking that if I get the tube re-installed in the hole, seal it, taking advantage of the wicking properties of the Seal-all adhesive, I can accomplish a fix without involving high heat. Also, part of the fix will be to see if I can reposition the tank so that the fill tube has an equal clearance on all sides of the hole in the floor of the cab. Next, is to buy a new, more flexible, rubber connector between the two metal tubes. Hopefully, that will give the assembly better protection from vibration that probably caused the tube to come loose.

[gordr]

Seal-all is OK for pinhole leaks, not for something like that. Altair has it right. Get a large soldering "copper", which is, as its name implies, just a big slug of pure copper, worked to a pyramidal point. Look for one at least a pound in weight. Clean any rust off the joint area with abrasive cloth, and then wipe the joint area with a cloth wet with hydrochloric acid, which will leave the metal bright. Away from the tank, meaning yards away, not inches, use a propane torch to heat the soldering copper until it's hot enough to really melt solder. Runny, not pasty! Heat it a little longer. Bring the hot iron to the tank, apply it to the joint, and work the end of a piece of acid-core solder under the tip of the copper. It will melt, and help carry the heat into the workpieces. Slowly move the copper around the joint, ensuring that the melted solder has fully wetted both parts of the joint. You have soldered before, you know the drill. It may take a couple of trips to the torch to reheat the copper. Once you have the workpiece sufficiently heated, solder will melt and wick into the joint when touched to the work.

A hot soldering copper will not ignite gasoline. It takes a spark, or an open flame, so it's perfectly safe. Just ensure your torch is well clear of the area, bearing in mind that fuel vapors are heavier than air.

No reason a big, say 250 Watt, electric soldering iron couldn't be used.

[Skip Lackie]

I've had the gas tanks out of 4 or 5 C-cab trucks, and on all of them the filler neck was way off center from the hole in the cab floor. I can't remember if the mounting holes in the two brackets are oblong or just round, but it would be worth it to hog them out a bit to allow the tank to be moved 1/4" one way or the other. The tank is usually right up against the inside of the frame rail, but there's plenty of room in the other three directions.

[StudeNorm]

I have succesfully repaired gas tanks using Alan's method of filling with water first (post #4) and using a propane torch to get the required heat. Remember that the area that requires adequate heat is the complete circumference of the joint. Any less and you won't get proper wicking action around the neck and you could end up with leaks or another failure. Dry ice in the the water would also help displace gas fumes, if present, but a thorough rinse with a concentrated detergent should clean any fuel remnants out. I have seen cast iron tanks absorb fuel such as propane gas over time and that makes for interesting effects when welding but automotive gas tanks use a much less porous steel so that should not be a problem.

Your final thought should be, if there is any doubt leave it to the professionals, such as a rad shop.

[sasquatch]

The filler pipe on my trucks tank broke loose (not off). My local radiator shop soldered it back on and while he was at it, he installed a new drain plug as the original one wouldn't come out. Price was very reasonable.

[jclary]

I've had the gas tanks out of 4 or 5 C-cab trucks, and on all of them the filler neck was way off center from the hole in the cab floor. I can't remember if the mounting holes in the two brackets are oblong or just round, but it would be worth it to hog them out a bit to allow the tank to be moved 1/4" one way or the other. The tank is usually right up against the inside of the frame rail, but there's plenty of room in the other three directions.

Thanks for the comment regarding how the gas tank filler tube aligns with the hole in the cab. Good to know it is not just my truck. Until I take the time to really study the mounting points...I won't know how much adjustment will be possible without having to make it more of a project than the benefits deserve.

While searching the topic "off-site," this link popped up http://forum.studebakerdriversclub.c...ng-filler-neck

Excellent discussion we have had in the past. Considering how serious the safety issues of this topic are, repetitive discussion is a good thing.

There is another type of soldering we have not discussed. It is called "resistance soldering." For my knowledge, it is mainly used in small, delicate, applications. It is used extensively in modeling. Folks building miniature operating steam locomotives, etc., have used it for years. I have a friend, now in his nineties, a former P-51 Pilot, who built the most impressive detail model of the Civil War Hunley Submarine, using a resistance solder unit. I just don't know if there is one that could handle a part with the size and mass of a filler tube joint. Even with such pin point accuracy and targeted heating...safety issues should still be observed.

[Deaf Mute]