I have a 4" cast iron wye that is weeping slight moisture and rusty growths. There are no visible cracks or holes and no water is dripping to the floor although the thing is "weeping". I can paint the thing and then within a week little pinhole rusty stuff starts to poke thru.

Is there any way besides total replacement that could give this fitting some time and stop the exterior weeping and rusty stuff?

At what point do I give up and bite the bullet on something like this?


(PS- I know plumbers are not into quick fixes and I know the right repair is replacement at some point but I thought I would ask before exploring that options)

if you can get your hand on some of the old roofing tar that comes in a solid form and they used to melt it and mop it onto roofs. you heat the leaky spot and melt some of the roof tar into it.
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i have a few chunks of it that i use for just that purpose.
once in a blue moon i pack and pour a lead joint. i always break up a few small pieces of that tar and put it on top of the oakum before pouring the molten lead.

The seepage that you are seeing from the lead joint is very common on calked fittings. It does not indicate a failed joint but rather is a result of the resin (rosin?) that is in the oakum. You could try peining the lead all around the joint, especially the bottom half in an attempt to seal the lead tighter and keep it from weeping.

Is it weeping at a joint or in the middle of the fitting?

i got the impression it was weeping in the middle.

I should have been more clear, this is weeping on the surface of fitting itself, not the joint.

if you can find some of that tar, that will fix it.
don't be afraid to get the spot nice and hot. that will dry it and allow the tar to melt and penetrate the hole.

I thought about coating it with roofing tar..... It has to be that material you describe? How about the basic "blackjack" type stuff that you can spread on with a putty knife?

That will surely make a total mess... I hate roofing tar.

Im real confused... its minor but annoying and proof it is failing. Im not going to get into why replacement isn't easy....

Say you get called out on service and see this... at what point (condition of the pipe) do you recommend to your customer total replacement?



Edited 2 times.

just like an antique dealer will 'ring' a glass to see if it is damaged, I do the same to cast iron. I use the end of my jackknife and tap the pipe. if it 'rings' kinda like a bell it is still good. if it thuds like a rusty fender on a F450, I recommend replacement.

It is leaking through within a week of painting? Time to bite the bullet.

there was a reason that the manufacturers of XH soil pipe put a heavy coat of tar on the pipe and fittings. cast iron pipe by its very nature is somewhat pourous. the tar would find any pinhole and seal it.
painting over a pinhole will not stop a weep but that doesn't mean it is time to replace. i can't tell you how long a melted tar repair will last. in fact if the pipe is worn then it should be replaced not tarred. but if it is weeping thru a tiny sand hole in the cast, properly dried pipe with tar melted into the leak will last a good many years.
also, once the tar has cooled and set up, it won't rub off like roof cement will.

" It is leaking through within a week of painting? Time to bite the bullet."

yes, after a week moist flakey puss is appearing.... a few are pinhole size and there is one where its about a fignernal size. Also a portion of the paint bubbled in a small spot after a week..... I relieved the bubble by poking it with a pin and rusty colored moisture had filled the bubble.

If, and only if, you have clearance all around the fitting, as a TEMPORARY fix:

Self melding tape - stretchy and sticks to itself



ask for it at an actual plumbing supply or a 'real' hardware store

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638