I would like to install on a one piece Kohler toilet a bidet. When I tried to unscrew the screw from the seat, it just didn't move, not with the screwdriver nor the drill. So I put wd40 but still doesn't move. Can u please help me.

  • You want a penetrating oil like Kroil. WD-40 is not penetrating oil. It is Water Displacer (hence: WD). It was made to stop rust on missile tanks. – Harper - Reinstate Monica Jan 8 '16 at 2:27
  • So the screw doesn't move with a drill at full power and also doesn't start to strip? This may mean you need more muscle or a better drill. Also you can use some pliers to get it started. – DMoore Jan 10 '16 at 5:55
  • Thank you for answers, but this is a one piece Kohler toilet. I don't have reach to the bottom of the screw. We tried with pliers & an electric dril. Still not moving – Sandy Jan 11 '16 at 21:48

I was away & finally found The Answer to your problem. Your problem is Kohler & their very bad design. They use "anchors" & it's quite ridiculous, here are a couple of videos to demonstrate handling of Kohler's anchors.

Video 1

Video 2

  • I can't remove the seat, the screw doesn't move – Sandy Jan 11 '16 at 21:49
  • Sorry, I was suspended for a week. If you haven't had any luck & can't get to any underside nut there's only 2 options left. First & kind of tricky is to drill-out the screw, you'll have to guess & go to bigger drill bits until the screw head pops off if you can't see how big the screw is. SECOND & YOUR BEST OPTION, is to remove the whole toilet. The nut for the seat screws is inside & should let loose from there. That toilet is heavy, maybe 100-lbs, & get all the water out that you can. Or, call Roto-Rooter. – Iggy Jan 16 '16 at 1:46

We have 3 Kohler 1-piece Rialto toilets. I replaced the seats on all 3 of them. The first two took about 2 minutes each. Unscrew bolt, replace seat, re-screw bolt. But the 3rd toilet had bolts that would not budge. I bought an impact screwdriver from Amazon and went to work. Using a small sledge hammer the first bolt finally loosened after about 30 blows. What a workout! The second bolt was more stubborn and the groove (flathead) at the top was beginning to widen causing the flathead bit to slip. I used layers of heavy gauze and plastic waterproof tape to narrow the groove and finally got the thing to unscrew. What a pain!


This problem is caused by a basic design error. The bolt is stainless steel and the anchor is aluminum. These metals are never supposed to be used together in a fastener due to galvanic / bimetallic corrosion. This is particularly true on a toilet seat where the anchor will be exposed to acidic / alkaline fluids and cleaning products, which promote galvanic corrosion. The aluminum anchor will corrode and 'glue' itself to the bolt.

I just ordered a replacement set, hoping that they fixed this Engineering 101 problem. Nope! Same aluminum post with a stainless steel bolt. See the photos below.

I notified Kohler and sent them a galvanic corrosion metals chart and photos. No reply yet. I did find one potential online source for stainless steel molly / sleeve expansion bolts.


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