Can't remove seat bolt from this 10-yr-old Kohler toilet

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68bucks

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We installed a Kohler one-piece toilet in 2013. The 'Quiet Close' lid failed so I tried to remove the lid bolts. No go on one of them; the bolt was frozen. I finally removed it and found that the anchor nut is made of aluminum, and the bolt of stainless steel. This is very basic design flaw! Aluminum fasteners should NEVER be used with steel or SS due to bimetallic / galvanic corrosion, which will cause the bolt to freeze on the nut. I managed to separate them and found clear evidence of bimetallic corrosion. I sent a complaint to Kohler USA; it will be interesting to see if and how they respond. Attached is a photo of the frozen bolt after it was removed. You can see the green annodized anchor which broke -- and the SS bolt. Also attached is a metal chart that I sent to Kohler which shows compatible metals in green -- and pairs that will cause corrosion in red. This is engineering 101 stuff.
The chart has aluminum and SS as compatible(green) . We used a ton of SS bolts at work (retired engineer) and we often used dissimilar metal nuts with SS bolts. SS nuts and bolts have a nasty propensity to gall when you tighten them then you can never get them off without cutting them or breaking them off. That's pretty darn hard with a 5/8" or 3/4" bolt. I'm guessing that is why they used different metals for the nut and bolt.
 

ilyaz

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We installed a Kohler one-piece toilet in 2013. The 'Quiet Close' lid failed so I tried to remove the lid bolts. No go on one of them; the bolt was frozen. I finally removed it and found that the anchor nut is made of aluminum, and the bolt of stainless steel. This is very basic design flaw! Aluminum fasteners should NEVER be used with steel or SS due to bimetallic / galvanic corrosion, which will cause the bolt to freeze on the nut. I managed to separate them and found clear evidence of bimetallic corrosion. I sent a complaint to Kohler USA; it will be interesting to see if and how they respond. Attached is a photo of the frozen bolt after it was removed. You can see the green annodized anchor which broke -- and the SS bolt. Also attached is a metal chart that I sent to Kohler which shows compatible metals in green -- and pairs that will cause corrosion in red. This is engineering 101 stuff.
Interesting, thx. Learned something new today!
 

Eddie_T

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On my one piece Kohler Rochelles the seat bolts have plastic nuts that are accessible in the tank. They were purchased in 1973 and I did hate paying $100 for a replacement seat. However If a toilet can be considered good looking they are the prettiest I have ever seen.
 

BvilleBound

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The chart has aluminum and SS as compatible(green) . We used a ton of SS bolts at work (retired engineer) and we often used dissimilar metal nuts with SS bolts. SS nuts and bolts have a nasty propensity to gall when you tighten them then you can never get them off without cutting them or breaking them off. That's pretty darn hard with a 5/8" or 3/4" bolt. I'm guessing that is why they used different metals for the nut and bolt.
Dear 68Bucks: It appears that you misread the galvanic / bimetallic chart. Aluminum and steel / stainless steel are red, indicating that corrosion will occur. Attached is another copy of the chart with blue arrows highlighting the intersection. Kohler engineers made a very basic Engineering 101 error. If you check their website, notes about the seat anchors / bolts talks about corrosive cleaning agents leaking down around the bolt and causing corrosion. They appear to have misunderstood the problem they created.
 

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68bucks

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Dear 68Bucks: It appears that you misread the galvanic / bimetallic chart. Aluminum and steel / stainless steel are red, indicating that corrosion will occur. Attached is another copy of the chart with blue arrows highlighting the intersection. Kohler engineers made a very basic Engineering 101 error. If you check their website, notes about the seat anchors / bolts talks about corrosive cleaning agents leaking down around the bolt and causing corrosion. They appear to have misunderstood the problem they created.
I see what your indicating, this table is sort of strange now that I look at it. I just went down the left side found SS and went down from the top under aluminum to the place I circled.
 

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BuzzLOL

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the bolt was frozen. I finally removed it and found that the anchor nut is made of aluminum, and the bolt of stainless steel. This is very basic design flaw! Aluminum fasteners should NEVER be used with steel or SS due to bimetallic / galvanic corrosion, which will cause the bolt to freeze on the nut.
I would have checked a Kohler seat in the store to see if Kohler did that or a repairperson/installer did that...
 

Eddie_T

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What I hate are those Chinese bolts and lift wires that are aluminum or something else plated to look like brass.
 

BuzzLOL

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What I hate are those Chinese bolts and lift wires that are aluminum or something else plated to look like brass.
Hard to believe plated parts can be made for less than simply using the real material...
 

Eddie_T

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Urine spray makes toilets/seats an extremely corrosive environment... S.S. bolts and S.S. nuts with nylon locking inserts would be fine since you don't have to tighten them much on a toilet...
Now that I have to scrub the toilet I find the sitting position to be best for all functions.
 

BvilleBound

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I just received a new 84999 Kohler toilet seat anchor / bolt replacement kit. I hoped that they fixed the basic problem with an aluminum anchor and stainless steel bolt -- which are never supposed to be used together and cause galvanic corrosion. Nope! The new kits have the same problem! I notified Kohler and sent them all of the info; a PDF copy of the letter with photos is attached below. No reply yet. This is a very basic Engineering 101 error.
 

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