gas tank leak ?

[Streetbobber74]

hello got a WL with a very slow gas leak from the bottom valve. could very well be a thread issue, wondering if anyone has any thoughts on a product that might work on the threads? if not the threads is there a rubber gasket i can try, wanted to try something small before i thought about sealing it from the inside. thanks scott

[Streetbobber74]

here is a pic of under the tank seems to be coming from above the black ring

[sirhrmechanic]

That is a PITA spot for a leak. Some things to try... take the fitting out and make sure the threads, etc. are good and you don't have rust piled around it. You may want to lap it back in. Make absolutely sure it seats fully (or at least far enough that it will positively crush the washer.) Also, make sure that when it seats, the flanges are perfectly parallel.

When putting the fitting back in the tank. Use a NEW aluminum or copper crush washer. Not sure what Harley used on the WLA's, but most of the time when I do a banjo fitting, I use a dead soft aluminum washer. Copper washers also work. Note that both copper and aluminum washers are one-time-use only. Once crushed, they work harden and don't seal as well. Also, use a good fuel-proof sealant. I prefer not to use teflon tape (or the fuel-proof equivalent) but if threads are worn, it's often the only way to take up the gaps short of machining and lapping in a new custom fitting.

Tighten well, but don't go so tight that you munge the threads. Use a new aluminum washer on both sides of the banjo.

Hope that helps. And hope that the issue isn't a pinhole in the tank near the female threaded insert. That's welded or brazed in and if the junction (or tank metal near the junction) is getting thin, the leak may be around the fitting, not through it. Weld and brazed areas are often the first area to rust, because of what the heat did to the metal during welding or brazing.

Key thing is new crush washers and making sure the surfaces are parallel and clean.

Cheers,

Sirhr

[Streetbobber74]

Thanks for the quick response, Im going to get going on it tomorrow, any recommendations for a fuel-proof sealant? i tried the internet, a product called Seal-All comes up for oil and gas. thanks again for your time and information.

[sirhrmechanic]

We use a non-silicone grey sealant that I can't remember the name of. We keep Silicone as far away from components as we can, as it does not like paint. I'll see if I can find out what we use. It's something like 1187. If you aren't planning on painting the bike or tanks any time soon, Ultra Copper silicone will work fine. As will high temp black silicone. Copper washers/aluminum washers should seal w.out sealant... but belt/suspenders never hurts.

Cheers,

Sirhr

[rdillon]

Permatex #1, dries hard, gas won't hurt it. Try it for a quick fix.

[Rod K]

Tom Cotton the guy that makes the "peek seals" for manifolds, also makes sealing washers for Linkert carb bowls. These will also fit the gas
shutoff. Put one on the top and bottom of the spacer ring. I've had very good results with these....Rod

[BigLakeBob]

I have found that if you do not have access to a new copper washer that is work hardened, you can take a torch to it to anneal it back to a soft state. After heating, quench in water. Bob#6738

[Rollo]

Used to have a lot of issue here and at the carbs with gas seeping. The washers everyone here is refering to are actually brass and there are two of them. I keep a bag of them around. Old Dude has them. I also use Permatex 51D pipe joint compound. It is gas and oil resisitant and made for this kind of application. It comes in a 16 oz can and has a small brush applicator to brush on the parts. The area needs to be clean and dry!. Simply brush this stuff on wait a little and put it back together. I have never had a problem if I did it right and believe me I have 20 bikes. If you have a little on some parts after assembly you want to clean off simply use Brake Clean on a rag and it comes right off. Make sure you let it set up for a couple of minutes before you reassemble and it works better. I used to hate going to the garage and it smelling like a refinery and risk blowing up my house. Now no worries.

Tom ( Rollo) Hardy
AMCA #12766

[Streetbobber74]

thanks guys for all the great info, much appreciated, ill let ya know how i make out. thanks again scott

[Streetbobber74]

it won't budge

ok guys, can't get this to budge, its solid, wondering if the someone in the past put something on the threads to lock it or something, but its not moving, gonna post some pics maybe someone can spot something I'm missingphoto 1.jpgphoto 2.jpg

thanks

[sirhrmechanic]

You might try using an air hammer-type impact wrench. Use carefully as those things can rip the sheetmetal apart. But the vibration may loosen things.

It goes without saying that you can't use a torch ;-)

If careful use of the air wrench doesn't work, you may have to pull the tank off and either drill or machine the plug out and replace it. You don't want to damage the sheetmetal around the joint or the braze.

Cheers,

Sirhr

[Streetbobber74]

after a few trying weekends, i was able to free up the nut off the tank, clean her up, apply some permatex to the threads and some form a gasket on the brass washers and she tight as drum and bone dry!!! can't thank everyone enough for all the great advise.
scott