MTFCA Forum

So I have a very small seeping leak from where the sediment bowl goes into the gas tank. I'm thinking that the guy who redid the tank for me hat the threads painted. I did as well with the sediment bowl. I used a gas approved sealent but I still have a small leak. So I'm thinking I need to get a tap for pipe threads. Are these 1/2 inch threads?

The leak is so small that it just makes the hood shelf paint a bit tacky.

Robert , Try a spark plug , then you know .
Toon

yes, standard pipe threads. They are tapered, so do not go too deep.

Look very carefully for a crack in the gas tank fitting. Due to the taper of the threads, if someone overtightened the sediment bowl in the past, it may have split the gas tank fitting. Sure hope not...

Hope it isn’t cracked but sometimes it won’t show up until you start tightening up the fitting . Gas has a way to seep out even though the crack is almost invisible. You may not see it when you take the fitting out so look very carefully.

remove, clean (as best you can) then apply Permatex 2A. Regardless of what you used before, I personally believe it is inferior to Permatex 2A for this particular situation.

if you still have a leak, then different approach is necessary but it isn't tapping the thread deeper. If someone thinks it is, then try to explain with a straight face just what running the tap in beyond it's designed length is accomplishing.

As someone else opined, I hope it is not a cracked fitting.

I see a potential problem. The fitting is threaded with tapered threads and you must turning it at the correct place to position the bowl at the bottom. So the thread is likely just a little deep. If you try to turn it one more turn, it might stop at the wrong position. So the permatex would be a good solution. Or possibly gasoline proof teflon tape around the fitting. Not close enough to get the tape inside the tank.
Norm

As for pipe size measure the diameter just before the threads.

With respect, Norm, there is no such thing as gasoline-proof teflon tape. Gas-proof tape is for gaseous use (natural gas, eg), but not for liquid gasoline.

I fell for that, too, and have even suggested it's use here on the forum years ago.

I was wrong

No Teflon tape belongs anywhere near a fuel system in a T.

Thank you for reinforcing that observation Scott !!!!!

1/2-in pipe threads are tapered. Run a tap through, clean threads, use thread sealant Gasoila on sediment bowl threads, reinstall.

Do not run a tap through. You will certainly upset the alignment of the tap outlet and the result is the need to realign the fuel pipe to the carburetor. Is the leak at the thread? Might it be from the outlet tap itself?

Allan from down under.

Try cleaning all the paint off the sediment bulb & tank outlet threads then use Permatex # 2 and see what happens !

Thanks for all the suggestions. I'm going to take it apart and see if when it was painted the paint got in the way of the threads. Then I'll go for the Permatex 2A. I know if you had to tap it you need a pipe thread tap not a regular one.

So I take it that this is the stuff to use. Says it's for gas.

that's the stuff, but for what you're using it on, that size will take you through to the rapture and beyond...I usually buy the tiny tube and use it for about 20 years. I use it only for pipe threads and not for gaskets or gasket making...for that I use Ultra Black. When sold in the little 1.5 oz tubes it is marked as "2A" and that's the only difference that I've ever been able to determine

Thanks Scott! I coulden't find a small tube. It's like when I bought a tube of EZ Turn. Ha!!! I'll be sure to leave it in my will.

so, you'll leave them the ultimate stick-er and the ultimate slide-er...
that'll definitely give them something to talk about at the wake...

Another trick I have used in these situations is lead, super clean the male pipe thread and run a bead of solder around the threads. If done right the solder will run around the threads and create a perfect seal. If the first attempt fails it can be reheated and the unwanted solder can be brushed off, some times the brushing can make a perfect seal. This is a bit tricky but I have used this method where screws have been stripped or damaged.