8N Gas Leak at Carb

acadianbob · Aug 23, 2013

OK, this ought to be simple. I bought a new gas shutoff valve and a new pre-bent fuel line for my 8N; the old valve was shot and the old fuel line had a bad crimp in it. I replaced the old with new and now have a considerable gas leak where the fuel line goes into the brass inlet/filter at the carb. I have the line as "straight" and "lined up" as I can. The plug into the carb is tight (and not cross-threaded). But I have a bad leak. I even used some pipe thread compound on the plug. The leak appears to come up the threads of the plug; and not between the fuel line and the plug.

Is it possible that I need to replace the brass inlet on the carb? I"m wondering if anyone else has run into this issue and solved it.

Thanks in advance for any tips.

Royse · Aug 23, 2013

Most of the time I find the fuel line connection is the leak, but it could be the elbow.
They can crack or have worn out threads, dirt in them keeping the line from seating, etc.
If needed, you can buy just the elbow with a new screen.
Its also possible that someone over tightened that elbow and
cracked the carb, but lets hope not!

Bruce (VA) · Aug 23, 2013

" I even used some pipe thread compound on the plug. "

Don't waste your time. It does not seal on the threads. It seals on the flare.

" Is it possible that I need to replace the brass inlet on the carb?"

Yes.

Don't honk down on it; it's brass. First, use a flare wrench to remove the fitting. (as in the picture) Next, if you do not have another fitting to screw into the elbow (as in the picture) then use a crescent wrench on the top & bottom (NOT the sides) of the elbow to remove it. Otherwise, you will distort it & you will never get the fuel line fitting back into it.

75 Tips

acadianbob · Aug 23, 2013

Thank you Bruce. I would not have thought about what you just said. I got a new elbow/filter but I'll use your method to install it.

I did tighten the old elbow (the wrong way, on the sides) and may have deformed it as you point out.

acadianbob · Aug 23, 2013

Thanks Royse. I did get a new elbow. But I'll be smarter this time.

souNdguy · Aug 23, 2013

one trick you cab do ont hat flair to carb line is loosen/remove the arb.. get the line on perfect.. then install the carb.. make the line bend after it is tight and square.

trying to get the fitting correct when not squre is almost imposivble and have it leak free for that type of fitting.. but getting it tight and sealed first.. works fine..

acadianbob · Aug 25, 2013

Got all new parts; elbow, gas line, fuel shutoff. Followed most of the great advice I got on the board (and I mean that sincerely, thank you). AND IT STILL LEAKED; BADLY. Took the fuel line totally off again. Noticed that the flange on the fuel line that goes into the elbow didn't look even. Filed straight across the flange and re-installed. Leak was still there but way better. Filed some more material off the flange. Re-assembled and NO LEAK. Disappointing that new parts are not up to the job. It was the flange all along!

Thanks everyone for the great input. I learned a lot on this one.

8N Gas Leak at Carb

acadianbob

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Royse

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Bruce (VA)

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acadianbob

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acadianbob

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souNdguy

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acadianbob

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