Gas Trank Repair

fer100 · #1 11-08-2009, 10:16 AM

Got a quick question. I have (2) CC100 gas tanks. Both leak at the nipple at the bottom for the tank. They have been repair before by PO. One has nipple one has threads. Are these tanks suppose to have threads or a nipple on them? How do you go about repairing these tanks? I don't think a open flame would be advisable. I've tried to use pipe wrap on them but, they still leak . A new tank is $200.00.

Rhoderman · #2 11-08-2009, 10:50 AM

If it's a nipple, can you remove it with vise-grips or a small pipe wrench? Then, clean up the threads with a pipe tap and put a new brass nipple or valve in there with some teflon tape.

I don't know what the original config was since mine isn't anywhere near original.

You can solder or weld them, but you are correct about being very cautious. If you rinse it out well and fill it 7/8 full of water, you should be okay. If it's been soldered or brazed, you probably won't be able to weld it without great difficulties.

Yosemite Sam · #3 11-08-2009, 12:24 PM

Just like Rhoderman says, the nipple will come out and the tank needs to be rinsed very, very well if you intend to apply an open flame. And you may have trouble depending on how it was repaired before. Personally I don't like to use Teflon tape on gas lines, but that's just me.

If you have tightened the nipple and it still leaks then the problem probably isn't with the plumbing... I've never had to repair a tank from a 100 but I've done several of the round style 7hp tanks, the larger square type tanks may just have the flange "crimped" into the hole, but I'm not sure.

On the round style tanks there is a square flange that is soldered into the hole in the bottom of the tank that the nipple screws into, chances are the solder is cracked/deteriorated or whatever. That is most likely where your leak is.

Wire wheel all the paint/rust off the bottom of the tank where the flange is, (once you get it good and clean you should be able to see the outline of the flange in the solder). Screw a longer nipple with a cap on it into the hole, put some water in the tank (you gotta rinse it anyway) stand the tank on it's end on your bench, and watch carefully you will see water droplets starting to form where the leak is. Keep in mind that water won't rush through a leak like gas will so you may need to apply sideways pressure to the end of the nipple to "open" the crack up a little to find the leak. Once you have found the leak, just clean and solder it like you would anything else, but use as little heat as possible so you don't warp the sheet metal or heat the solder so much that the flange falls out of the hole (I had that happen once).

I have soldered several tanks with good results. I know that the thought of doing this is kind of nerve racking, but the THOUGHT of doing it is really worse than actually doing it.

There are also different products on the market made to "stop" fuel tank leaks, but I've never used any of them.

TBell · #4 11-08-2009, 01:10 PM

I have had awesome luck with "RED-KOTE" fuel tank liner. Just follow the directions on the can and you'll never have a leak! I tried it on the tank for my A/C B-212 which looked like swiss cheese on the bottom, know not a drip.
Terry

fer100 · #5 11-08-2009, 03:06 PM

Thanks for the information guys. I'm in the process of cleaning out the Cubs from the garage, going to cover them up outside for the winter. Wife wants her garage back. I got brave and used some force and got the nipple off . It looks like someone got to this tank and tried to repair it. I'am going to go down to the hardware store and get some new fittings. Teflone tape the connections and retighten them and see if it leaks. Will keep you posted

esarvey · #6 11-22-2009, 12:47 PM

Back in the day's(60's), I worked for BEC HEIL CORP. We repaired/welded gas,fuel oil tankers, My starting job was steaming out, the tankers before they could even be driven into the shop. That makes them safe to weld on,fill them 7/8 with water after,seal & apply 5 lbs. air pressure to test for leaks. hope this helps, to save some bad tanks.
GIG
BIG
PAC!
Daduke

fer100 · #7 11-22-2009, 03:34 PM

Thanks for the response all. After removing the fittings that were attach to the tank and cleaning them up. it looks like the fitting might be the problem. It had one male/female fitting that screwed into the tank, and a double male that scewed into that. the female male end has a fine hairline crack in it. the double male won't screw into the tank. The problem is trying to find the proper fittings. Tractor supply and the auto stores don't have the correct fittings. Going to stop at a small engine repair shop to see if they have something. What is the correct fitting that goes into the tanks? I need to get the fittings for the tank so i can pressure test the tank for leaks. The bottom of the tank looks rough but not bad enought to leak.

Matt G. · #8 11-22-2009, 05:41 PM

It should be 1/8" NPT. Any decent hardware store should have what you need.

thenrie · #9 11-24-2009, 08:44 AM

I have been acquainted with welders in auto shops who say they fill empty car gas tanks with CO2 before welding on them. Gas fumes still need oxygen to combust, so filling the empty gas tank with CO2 allows the CO2 to displace the air in the tank, ergo no oxygen, no combustion. Never done it myself. Gives me the willies!

cwmcbee · #10 11-24-2009, 08:55 AM

I've seen it done to convert an old butane tank to a roller, they put a hose off the exhaust and left their engine running, I saw it from behind a tree waaay back. I also worked one incident where it didn't work and and he died a slow miserable death. Please don't do this there is no area for forgiveness if you make a mistake. Something as small as a Cub tank would fix you to where your kids and grandkids wouldn't know you.