Forum Title: Can't get a seal -- O ring and uneven flanges
I screwed up my project and now I need some help. The plan was to remove the Kohler Pressure Balancing Unit (PBU) from the copper valve body and replace it. This video is almost exactly what I was trying to do. The PBU removal is at 1:09. Note the image of the two inlet flanges at the back of the valve body at 1:19 ┬û that┬Æs where (I┬Æm pretty sure) my problem is. YouTube When I removed the old Kohler PBU the two flanges in the back of the valve body were all grimed up. I decided to clean them. To do that I (stupidly) attached a wire cup brush to my power drill (see the link below for a pic of the brush), inserted it into the valve body, and spun the hell out of it. http://www.homedepot.com/p/Avanti-Pr...D01G/202831065 That worked great in that is shined the copper up nice and bright. The problem was that the wire brush carved grooves into those copper flanges. Because of the grooves, the O rings on the back of the Kohler PBU wouldn┬Æt sit flat against the flanges, and the whole thing leaked like crazy. (Which is to say, when I turned the water supply back on at the main, without opening the shower valve, water just poured out of the bathtub spigot). You can see the O rings on the back of the PBU at 1:40, below. YouTube So I took the whole thing apart, got a small piece of sand paper, and sanded those flanges down, trying to sand out the grooves. I put the whole thing back together, turned on the water, and found the leak improved but was still there. Over the course of the next six hours, I did this over and over and over again until the leak was reduced to a small, slow drip. But I just can┬Æt get it to completely seal. I┬Æm worried that the problem is that even though the flanges are now smooth from all my sanding, the wire brush took out enough copper so that the flanges are now SMOOTH, but no longer PERFECTLY FLAT. And if one or both flanges are not perfectly flat┬àwill the O rings on the back of the Kohler PBU ever seal correctly? I┬Æm desperate to find a way to get those O rings to smash tightly against those flanges. I┬Æve tried different grits of sandpaper. I┬Æve tried large amounts of silicone grease (which, to my surprise, seemed to make things worse) and small amounts of silicone grease (which seems to help a little). I tried tightening the screws that hold the whole thing together as tight as I could, then I tried backing them off for fear of overtightening (I┬Æm not sure either approach made a difference). Does anyone have any ideas how to get those O rings to smash tightly against those copper flanges if the flanges are not perfectly flat? Putty? Grease? Pipe dope? Teflon Tape? Some kind of super awesome O ring? Anything at all? I┬Æd prefer not to use plumber┬Æs goop as that┬Æs an adhesive ┬û if it doesn┬Æt work, there can be no plan B because I won┬Æt be able to get the PBU out again. And I really, really, don┬Æt want to have to replace the entire valve body. Thanks!
Post By: BARRY MONTGOMERY (Franklin, WI), 01/30/2017
Might take a bit of leg work but go look for a couple of O-rings that are a just a tad thicker than the original ones. Rub a thin coat of stem lube on them to help hold them in place. I watched the video after I made this reply ^ You took off some brass so a thicker o-ring just might do the trick