How to repair a leaking water valve?

October 6, 2009 5:44 PM

I have a cast iron valve on a basement water (cold supply) line that is leaking. It's an antique so there is no repacking it and in a fairly inaccessible location so cutting it out and replacing it is bound to be an expensive nightmare involving a real. This valve is redundant and does not need to be functional. I was wondering if there is a product (I'm thinking a gooey oakum type thing) that I can wrap around the valve stem to form a seal? This will have to work in a wet environment as there is no way to turn the water off before the leaky valve.
posted by cedar to Home & Garden (10 answers total)

Response by poster: Unfortunately we are trying to avoid involving the city and the keys aren't that easy to come by -- the city main probably isn't in any better shape than my basement and they really don't want people messing with them. Even then, because of the way the galvanized runs along the joists and the overall condition of the joints, replacing this valve is going to be beyond my ability. There are a few too many threads to cut and the quarters are awfully tight.

As cheesy as it sounds, I know the right way to fix this (hire a plumber, you cheap sob) but am looking for the quick fix.
posted by cedar at 6:00 PM on October 6, 2009

Best answer: There is no cheap fix. the longer you put off fixing it correctly the more it will cost you. Just think about the damage that will happen when it blows out one night at 4am.
posted by patnok at 6:04 PM on October 6, 2009

You can patch it while wet with Fiberglass tape. Home depot or something will sell them in a pipe repair kit. Make sure you get the ones that can cure "even while underwater". It'll stop the leak as long as the pressure is minimal. You might want to cover with a piece of inner tube before applying the fiberglass tape. Wear gloves!

This is only temporary and it probably won't last long.
posted by Khazk at 6:12 PM on October 6, 2009

There are assorted products like this or this and fusion tapes.

I've used fusion tapes for sealing electrical connections for which they work quite well but never a pipe under pressure. Sure wouldn't hurt to open all the taps in your house before wrapping to reduce the amount of pressure behind the leak. Also you'd want to clean up the outside of the valve with a wire brush first to get good adhesion.
posted by Mitheral at 6:24 PM on October 6, 2009

Epoxy putty is what you want. But as stated above, it's a temporary fix.

Replacing those old galvanized lines with copper or PEX will do wonders for your water pressure.
posted by electroboy at 6:31 PM on October 6, 2009

You could always just not pay for water until they turn it off at the street, get the fix, and pay your water bill. I did that when I was broke, single, had a leaky valve, and didn't mind bumming showers off a friend for the two days it took for the water company to come back out and turn me back on.
posted by notsnot at 6:52 PM on October 6, 2009

I asked my husband, who recently did some cast iron pipe work on our house this last weekend and is generally pretty handy.

"If it's leaking at the stem, all you have to do is tighten the nut at the base of the stem. If it's leaking someplace else...there's nothing you can do to wrap it, because the water pressure will work its way through. You might be able to use an epoxy putty like J-B Weld, that might seal it."
posted by Lucinda at 7:31 PM on October 6, 2009

Best answer: Water is virtually incompressible, so anything you apply to the outside of a leaky pipe will eventually need to resist as much pressure as the pipe itself does. So your patch needs to be quite strong. If the leak is faster than a slow weep, it will be doing its best to detach your patch from the pipe before it has a chance to adhere or set or both.

I'd try wrapping it tightly with dry oakum that's been teased out and thoroughly impregnated with quick-setting cement powder, to achieve an industrial-grade plaster cast effect, using seepage from the leak itself to make the cement set. Provided the leak's slow enough not to wash the cement powder out, this should seal things up pretty well.
posted by flabdablet at 9:20 PM on October 6, 2009

Assuming that lubricating and tightening the valve stem nut does not bring joy.
Depending on the shape of the gate valve stem area, a emergency fix can be had by: Remove valve handle, wire brush the valve gland area for better adhesion.
Take some auto radiator type hose or better, size that will fit over and beyond the gland nut assembly and long enough to extend well beyond the end of the stem.
Slather valve nut/gland area with proper epoxy, shove on hose to past gland, add real stainless steel hose clamp or two, make very tight.
Leave other end open as a drain till epoxy is dry, then plug with copper pipe cap and add hose clamps.
I've done this with water and other fluids and sealed it till repair or left the hose long and drained it into a barrel or out a window.
posted by blink_left at 11:45 PM on October 6, 2009

Eh, I dunno about using oakum. We use it, along with hydraulic cement, to fill cracks and seal around pipes in manholes, but I think it'd be of minimal use in this situation. It's good for filling voids, but not so much for pinhole leaks.

Googling some consumer solutions, it looks like this is probably a good bet. Combines the epoxy/fiberglass tape into one product.

Also, not to scare you, but we usually shut off the water to houses when we're relining the sanitary sewers. It's not uncommon for old galvanized water lines to collapse once the water pressure drops. In that case, the only solution is to have the service replaced from the meter to the house with copper or HDPE.
posted by electroboy at 7:44 AM on October 7, 2009