TN series petcock leak

[whitew29]

Hi there, I have a few tn28s I’m working with. One of the runners drips fuel from the tank cutoff and another one leaks just a bit. I’ve tried everything to stop the leak but no luck.  The other valve stems I’ve tried leak the same way. What am I missing? I’ve tried o rings in the compression nut as well as rubber washers.

[Buccaneer]

Some of those petcocks shut-off stems have a thin metal washer, with
an original seal behind it. They can be a pain to get apart, but I’ve had
some luck replacing the original rubber seal with a O-ring, if you can
find the right size.

Prepare to be boarded!

[whitew29]

Thanks for that.  There is a small washer on the stem so perhaps I need an o ring that fills the entire cavity? The ones  I have tried are rather thin. They don’t leak much while running its while its sitting that it has a slow leak into the carb.

[frankr]

I’ve had luck with wrapping cotton string around the stem as a packing.

[whitew29]

Do you mean like kite string? There’s not much room on there but I can see that working. I just tried a modified rubber washer and it dripped once in about an hour.  Much better. Maybe I should add the string.

 

[Monte NZ]

I have heard that winding dental floss round the stem will fix the leak.

[Mumbles]

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whitew29

[frankr]

whitew29 wrote:

Do you mean like kite string? There’s not much room on there but I can see that working. I just tried a modified rubber washer and it dripped once in about an hour.  Much better. Maybe I should add the string.

 

Never thought of a kite, but yeah, probably.  Haven’t flown a kite in the last 70 years, but some people have told me to.

[joecb]

Valve stem packing from the hardware plumbing section. Either the new teflon stuff or the old style graphite yarn. Or make your own from teflon plumbers tape by rolling the tape into a string. I would caution against using random “rubber” material, could be affected by the gasoline.

Joe B

[nabmd]

Make sure you get the YELLOW teflon tape, not the WHITE. The YELLOW is designed for gasoline.

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cajuncook1

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