Leaking Gas Tank

[JR03CHOPPER]

I developed a leak from my gas tank. The first time...I took it to a shop and had it pressure tested (supposedly). The leak seemed to puddle on the bottom left corner of the tank (obviously the lowest spot). It actually took the paint off, even though it wasn't leaking long. The shop said it was probably the petcock. They removed it, cleaned it up, as well as the bung hole. After they put it back in, it seemed fine. Less than a month later...started leaking again. About 5 drops a minute. Still in the bottom left corner. I drained and removed the tank. No pieces floating in the gas I removed. Fuel line appears to be in good shape. When it was together...I did not see a "river" of gas leaking down the tank. I do not see a crack or hole in the corner (it is down to the bare metal). So if there is a hole/crack...it would have to be very small or in small weld on the bottom, in the well of the tank.

Any suggestions? I was thinking of rigging an air hose to the filling hole and sticking the end of the tank in a bucket of water...and look for bubbles. If I do find a hole...what then? I am thinking bondo won't work, since it is only 4 inches or so above the rear head. Not to mention 93 octane with Ethenol making direct contact.

Help would be greatly appreciated.

 

[Diesel Dan]

Well first of JR........I would get an air-psi regulator,and only pressurize the gas tank to no more than 5 psi.....That should be sufficient to find a leak:up:.........

THEN if it has a leak I would "Lead" it in......or you could have someone TIG it if you want......I'am old school so a pinhole I would lead it in myself, Lead is easy to shape and fill in.....Good luck bud!!!!!!!:2thumbs:

 

[HMAN]

Hey JR. I got the same problem. Pulled in the drive the other day after topping the tank and riding a bit. Kept smelling gas. Found gas dripping on the rear rocker box. I thought she was gonna burn in the driveway!! Turns out my rear tank mount has cracked and its leaking around the welds. I've got the split tanks so its just the left one, but PIA! Check around your tank mounts. Now its time to tear it down and fix it. Gotta repaint too. Good luck!

 

[JR03CHOPPER]

Well first of JR........I would get an air-psi regulator,and only pressurize the gas tank to no more than 5 psi.....That should be sufficient to find a leak:up:.........

THEN if it has a leak I would "Lead" it in......or you could have someone TIG it if you want......I'am old school so a pinhole I would lead it in myself, Lead is easy to shape and fill in.....Good luck bud!!!!!!!:2thumbs:

I didn't think of lead. Good tip. I have a regulated air line so I should be good there. I was thinking that maybe I should use the fuel line port on the petcock instead of the filler hole to conect the line. With an in line guage I can monitor how much is in the tank.

 

[JR03CHOPPER]

Hey JR. I got the same problem. Pulled in the drive the other day after topping the tank and riding a bit. Kept smelling gas. Found gas dripping on the rear rocker box. I thought she was gonna burn in the driveway!! Turns out my rear tank mount has cracked and its leaking around the welds. I've got the split tanks so its just the left one, but PIA! Check around your tank mounts. Now its time to tear it down and fix it. Gotta repaint too. Good luck!

Thanks. Luckily it is on the bottom of the tank! Not easy to see the crappy paint job we are going to do!

 

[pknowles]

I didn't think of lead. Good tip. I have a regulated air line so I should be good there. I was thinking that maybe I should use the fuel line port on the petcock instead of the filler hole to conect the line. With an in line guage I can monitor how much is in the tank.

Don't forget to plug your gas cap as it's vented.

 

[JR03CHOPPER]

Don't forget to plug your gas cap as it's vented.

Good point. Thanks!!

 

[Diesel Dan]

I didn't think of lead. Good tip. I have a regulated air line so I should be good there. I was thinking that maybe I should use the fuel line port on the petcock instead of the filler hole to conect the line. With an in line guage I can monitor how much is in the tank.

Your welcome bud.........Good Luck...keep us posted on how it turns out Brother....

 

[DynoDave]

Hey JR. I got the same problem. Pulled in the drive the other day after topping the tank and riding a bit. Kept smelling gas. Found gas dripping on the rear rocker box. I thought she was gonna burn in the driveway!! Turns out my rear tank mount has cracked and its leaking around the welds. I've got the split tanks so its just the left one, but PIA! Check around your tank mounts. Now its time to tear it down and fix it. Gotta repaint too. Good luck!

Had the same problem with a leak at the rear mount. Cleaned up the area down to bare metal, patched the area with automotive gas tank sealer (grey epoxy) and reinforced with carbon fiber cloth. Re-sealed the inside of the tank with Caswell. Worked perfectly and didn't require any welding or re-painting of the tank.

 

[I am Thor]

I did the same sanded the hole put Jb weld on it relined tank stood it on end and let it dry

 

[CHOPTOP45]

what ever you do don't put to much air pressure on the tank.

 

[grizfish]

Before and after Big Dog Warranty tank repairs summer 2003.
Having trouble posting photos. They welded the mounts.

 

[stlmikie]

If its leaking that bad, you could take the tanks off empty it of fuel. Put a liquid in it that would be easy to see and lit a little pressure in and you'll find it right now.

 

[JR03CHOPPER]

Update: it is a pin hole in the weld. Directly in the corner where the backbone well meets the flat bottom of the tank. Must have been 4:30 on a Friday when it was welded. It is astonishing to me that it took almost 11 years to become a true leak. I am going to take it to my local shop. Have them fix it so I can blame them if it leaks again. I am afraid to sand/grind it down before patching it. Especially where it is located.

Thank you for all the feed back! Much appreciated!!!

 

[pknowles]

The liner must have held up pretty good.

 

[JR03CHOPPER]

Were all the tanks lined? When I have looked inside, My friend has one of those pipe cameras with a light, it always just looks like metal.

 

[pknowles]

Were all the tanks lined? When I have looked inside, My friend has one of those pipe cameras with a light, it always just looks like metal.

I don't know what year they started lining tanks, but my 07 Bulldog has a liner and had to be replace in early 2010 because it was peeling off and the paint on top of the tank was blistering. I guess I had one of the last warranty jobs for what it's worth. some of the guys with the older dogs will chime in hopefully. God luck with the repair.

 

[FrankBDPS]

I just took the tanks off of my 2000 Prosport.There was something rolling around in one of them.When the filler caps were removed out came a piece of liner material about two inches long,an inch wide and almost a half in thick.What a fucking mess that turned out to be. Just another problem waiting to happen.Cleaned them out and relined them.I hope it works.

LA Dog has a 2001 Prosport and his liner failed also.

I really like my bike and would probably buy another one but I sure am glad I did not pay new price for one.it would be disappointing.

Another example,the rear pulley matches the wheels and has been chromed.Try to find another one.

I still like my bike!