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I'm repairing an old brass hot water valve for my washing machine. I've removed the old packing material and replaced it with new graphite packing rope. I've tightened the packing nut until it is firm, but when I test the valve, water still leaks out between the nut and the valve stem. When I continue tightening the packing nut, the graphite packing squeezes out between the valve stem and the packing nut, and the valve continues to leak. What am I doing wrong?

(I have tried doing the recommended "wrap the packing rope twice around the stem". I have also tried manually pushing the rope down into the void between the stem and the valve to minimize air gaps. Neither approach seems to make a difference.)

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I agree with JACK, but that rope (graphite or Teflon/PTFE) is only meant to rejuvenate and not replace the packing. Your only bet with that stuff, since you've trashed the old packing, is to probably use the whole package and over-fill the entire packing nut.

Otherwise, you need a tight-to-the-stem flat washer to backup the rope. Ideally, you'd only want a Squared-Off Stem Washer, like JACK has displayed...tall and fat.

Or, if your packing nut is domed, you might find Beveled Washers are the only way to a long lasting watertight seal. Beveled Washers can be either angled or domed. Beveled Washers

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  • Hmmm yes, but from the markings the washers pictured are rubber bibb washers. You would want actual packing washers made of composite material, which is available in many sizes and shapes, including beveled/domed, not just square-cut.
    – Jimmy Fix-it
    Jul 23, 2020 at 5:59
  • Yeah, sorry. I just wanted to get the point across and didn't find exact pictures elsewhere. Good eye!
    – Iggy
    Jul 23, 2020 at 10:55
  • The rope come in different diameters and shapes and can replace the packing if done right.
    – JACK
    Jul 23, 2020 at 20:25
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Using the graphite rope isn't as easy as you would think. First off, you need the right size rope that fits in tight with one wrap. You don't use a continuous piece. You cut a piece equal to the circumference and push the rope in and butt joint the ends. Then do it again with another piece of rope and rotate it so the ends don't even up with the previous layer ends of the rope. Keep doing this until the nut is full.

Better yet, get one of these kits. Picture from Granger.com

enter image description here

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    Picture attribution?
    – Michael Karas ♦
    Jul 22, 2020 at 20:07
  • That looks like a useful set of washers. What should I search for to find it?
    – Morgan Knighton
    Jul 23, 2020 at 18:49
  • @MorganKnighton You can get them at Granger.com or any plumbing supply store. These are packing material, rubber and graphite, not normal washers so make sure you get the right items.
    – JACK
    Jul 23, 2020 at 20:15
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Just in case, make sure you're wrapping the packing 'rope/string' in the same direction as the packing nut screws on. Otherwise as you screw the nut onward to tighten it, you're unscrewing the packing rope into a jumbled mess that could have gaps.

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