Help with fuel leaks

[Perry Mitchell]

I am getting ready to fire up my engine for the first time and so I was doing some pressure testing of the fuel system to make sure there were no leaks. The tank tested fine but I can't get the fuel and return lines to test. I filled the lines with 80 psi of air pressure and watched the gage drop to 0 in about 1/2 hour. I did it again, this time I sprayed a soapy solution on each fitting and found two that bubbled up, indicating a leak. I tightened them but they still leak. We are talking 37* AN fittings of various types here. I know Earl's has new aluminum conical seals available that are supposed to fix this problem. Maybe there is a sealant that can be used, such as a liquid gasket paste or Loctite. What are your experiences and what did you do to fix the problem? I know I can't be the only one that has had this problem. Thanks

[Smittys67]

If your talking about ss hard lines you have to make sure to file the seat if there are any burs, also on hard lines if you tighten and loosen them several times they usally seal.

[Perry Mitchell]

I am talking about 3/8'' (-6) SS hard lines that I flared myself. All the flares look good, I was carefull about that. I will loosen and re-tighten them several times and hope for the best. Thanks

[Hitman]

We had the same problems with hard lines. After all the messing around we traced it back to the type of ss tube we were using. The 304 ss welded will only work some of the time. We now use seamless tube and never had a problem again.

J

[Musclerodz]

One, always use seamless tubing. Second, recheck your flares. The leaks are caused by an incorrect flare or a flare with a burr on the end not allowing the line to properly seat. What fitting material are you using? Stainless as well? You may have to use a touch of antiseize to prevent galling which could be a problem as well.

[Garage Dog 65]

In aviation we see most of these leaks are the result of overtightening. As long as the deal is flared correctly and there are no burrs - it's almost always heavy handed tightening that induces the leak.