Gas Tank Leak Testing ???

[55 Fargo]

Hi all, I bought the Mopar gas tank from Tanks.Inc, it is now installed in my 47 Chrashler.

The filler neck screws on with 6 machine screws, so I am bit concerned whether I did the job right when attaching this neck, it uses a thick neoprene gasket, I also as recommended used Permatex Aviation sealant on the gasket surfaces as well.

I also ran new steel gas lines,I have 2 unions on the line from tank to fuel pump, I have not checked any of this or the tank for leaks.

My question is, is it possible to check this for leaks in a simple way, or should I pour in the gas and hope for the best..............Thanx Fred

[oldmopar]

Unless you have a way to pressure test it I would just put gas in it and see what happens worst case you would have to drain the tank.

[Plymouthy Adams]

you could use water and fill it to the top of the neck..then pressure it about 3 pounds max. capping it and getting a sensitive guage to read the low pressure could get involved..I would not recommend a vacuum test though...unless you are recycling the tank...as the tank is vented static prerssure is all it will see..filling it out of the car with fuel as it is lighter weight and will show leak faster..should suffice...that way you can remove the fuel prior to assembly and then filter it going bck into the tank..that way you have also flushed the new tank for any residue, trash in the manufactuering process.

[Norm's Coupe]

Fred,

I'm sure there is a pressure test you could run if you had the right equipment. That said, I tested mine for leaks simply by filling it up with gas. The worse that can happen is you have a little drip or dribble. If so, either drain it and reseal, run the gas out, or let it drip or dribble for a few days then reseal. A little gas on the floor won't hurt anything, just don't light a match. Or, park it outside for that short period either on concrete or limestone gravel.

Back when my old tank broke loose on me I had between 5 and 10 gallons of gas on my garage floor. That was a real mess. I could smell the gas outside the garage with the doors shut in the winter. When I opened the overhead door (with the electric opener) I had gas everywhere. Wifes car was also in the garage at the time. I simply let the air circulate to get rid of as much of the fumes as possible. Got in the wifes car, started it and got it out of the garage first. Luckily I still had a little gas left in the coupe so was able to do the same with it instead of pushing it out. Then dumped a lot of oil dry on the floor to soak up the gas. Really couldn't wash the floor because it was somewhere between 10 and 20 degrees outside at the time. So..........just left the doors open during the day for a couple of days to get rid of all the fumes and let what little residue was in the concrete dry out.

Remember, the fumes are more flammable than the gas. So, by getting rid of the fumes the gas is safer to work with.

[55 Fargo]

Tim, so disconnect the fuel line at the tank, make a short line to go back into a jerrycan, fill with gas at tank filler neck and watch for leaks. As the filler neck flange is near the top of the tank it will take about 8 to gallons of gas to reach that level to see what is leaking.

Maybe I should pour in a gallon or 2 of gas, start engine, check for leaks along new lines. Shut off engine, change gas filter, re-fill tank if not leaking, then see how sealed the filler neck flange is.

Sure would be nice to have someone like you or Norm M around to supervise me on this and many other fixes..........Fred

[55 Fargo]

Thanx Norm, I rmeber you story of the spilt gas in your garage, Murphys Law dictates this should happen in winter. I figure I will wait till warm spring weather first before I do this test. I am still running on a porta tank right now, man this thing and it's line never leaks

[Jerry Roberts]

If you have an air compresser , hook it up to the gas filler neck . All you need is a few pounds of pressure . Fill a spray bottle with soapy water and spray your connections and look for bubbles . Spray around the sender too . This method is a lot easier that possibly having to drain your tank of gas for repairs .

[martybose]

Personally I wouldn't worry about leaks from the gasket, it should be fine.

If you decide to pressure test it, DO NOT PUT A LOT OF PRESSURE INTO THE TANK!!!! We pressure test a lot of fuel tanks in the shipyard, and we never use more than 2 pounds of pressure; more than that will usually start to balloon any tank that isn't designed as a pressure tank.

Marty

[55 Fargo]

Here is a pic of a new fuel line union along the frame, I am not overly worried about these.....fred

[Niel Hoback]

Am I remembering right that "fat man" was the name of the a-bomb that dropped on Hiroshima? If so, why would I remember that?

[Norm's Coupe]

Norm used a garage door opener and started 2 vehicles in a gas filled garage:eek: and surprisingly is still here to write about it:)

*fat man-- this reference does not refer to forum members, cigars, a bomb or anything other than a level of a bet. In my early days in the USAF one of my supervisors would commonly bet you a "fat man" that he was right. He said that gambling for money was not allowed. In theory,the winner got the fat man do do their work for the rest of the day. Of course in reality, there was no fat man.

Shel,

Believe me, I was holding my breath and crossing my fingers and toes when I started the first car. The only reason I did it anyway was the fact I knew it was the fumes that was the most flammable and not the gas from what we use to do as kids in the backyard of my grandfathers years ago. When ever he was working on something he always used a pan or coffee can full of gas to clean his parts. We use to throw lit matches and cigarettes into the can and it just put both out on contact. That was because we were outside and there wasn't enough fumes to ignite the gas, so it put the match and cigarette out. As mentioned that was done outside though. That's why when I found the problem in my garage I let as much of the fumes out as possible before starting the cars. Once the cars were started I didn't waste any time getting them backed out of the garage.

[martybose]

Believe me' date=' I was holding my breath and crossing my fingers and toes when I started the first car.

(SNIP)

The first engine I ever built myself was a 289 Ford. It had chrome rings, and I was told to put it together absolutely dry. I've often wondered if the guy that told me that was pulling my leg, but that's what I did. Boy you have never heard a running engine squeek as loud as that thing was until it threw some oil around! I'm guessing I took about 20,000 miles off of the useful life of that engine by starting it that way.

Marty