Last week I removed the toilet so I could put down new vinyl tile flooring. While it was out, I bought a new tank mounting kit at Lowes....big donut center gasket, two new long bolts, two nuts and four each rubber or fabric washer and flat metal washers. I thought for sure the new mounting hardware would fix the problem. However, after reinstalling the commode there's STILL a small leak around just the right bolt. Tried backing off the other bolt and retightening the right one...no luck.
I drained, dried and carefully inspected the insides of the tank. I noticed there are 1/32 to 1/16" raised letters in the porcelain which say MADE IN USA in the bottom. Unfortunatele, part of the 'M' and the 'A' letters are so close to the right hole that the rubber washer has to fit over them. I'm thinking they create just enough of an obstruction that the the washer will not seal in that area. What I'd like to know from you plumbing-savy types is the following:
1. Can I file or sand the raised letters off the porcelain without harming its waterproofing ability?
2. If sanding porcelain could be problematic, I'm considering putting a small amount of either plumber's putty, pipe joint compound (aka pipe dope) or silicone caulk/adhesive between the rubber washer and the letters to try to seal the small leak. Which of those products would hold up best under water without harming the washer?