How do I tighten this bathroom faucet?

Question

My bathroom faucet is loose on the countertop. It wobbles and rotates when lifting and turning on the water.

Underneath it looks like the following pictures. (It's above and behind some drywall, so most of the pictures are using an endoscope; sorry about the low resolution.)

The inset-hex bolt here is the only obvious thing I could tighten, but it appears to just be holding the two rings together.

The threaded rods are clearly what I should be tightening, but I cannot see how to tighten them from underneath. (This photo looks like the large threaded rod might have spiderwebs filling a hex hole on the end; I later went back and scraped the end of the rod to find that it is solid and flat.)

Sticking the endoscope up the hole does not produce useful (to me) information:

Update: the answer by @Ecnerwal may be correct: I am now in the process of figuring out how to disassemble this (I find) Brizo faucet. I've popped out the hot/cold indicator under the handle…

…to reveal a hole with a 3mm inset hex set screw:

Loosening that allows me to lift off the faucet top…to show nothing interesting:

However, I can then unscrew the ring that was under the cap, to reveal a large brass nut:

Now I need to go to a hardware store to find something to loosen this nut, as none of my crescent wrenches are large enough.

Update 2: I now own a honking big crescent wrench, but did not find what I was looking for. Removing the brass nut gives access to the cartridge for the faucet, but nothing related to affixing it to the counter.

This is the correct follow-on to [this question](https://diy.stackexchange.com/questions/258578/how-to-tighten-this-sink-nut) of mine where I originally identified the wrong under-counter region that connected to the faucet, and so modified the question to be about that. — Phrogz, Oct 30 '22 at 17:42
@Ecnerwal The small rods are also threaded, oddly. Nuts and washers are interesting thought. However, it looks to me like the thick threaded rod is threaded into the lower flange, not just passing through. — Phrogz, Oct 30 '22 at 18:38
@Ruskes When I rotate the faucet the black flange does turn; when I wiggle the faucet it also moves, though not as much as I might have expected. — Phrogz, Oct 30 '22 at 18:38
You say it's a Brizo. Most Brizos are secured with a nut from underneath. Look at some Brizo instructions on any web site and see if maybe there was a nut that came loose and fell off of the threaded rod. If so there would be no way to further disassemble it from above. However, it does look like the larger rod is threaded onto the retaining ring underneath, in which case there must be a way to keep going from above! — jay613, Oct 30 '22 at 21:55
@jay613 Thanks. Yes, I looked at other Brizo, and even some of the others I have from that era and same line DO use a nut from underneath. But see the answer I just added: this one IS tightened from above. — Phrogz, Oct 30 '22 at 22:22
Congratulations on such a well documented methodical process, plus with photos that are well lit, properly focused and pertinent - even quite good when using an endoscope. || I'm an olde electrical engineer in NZ. A question I often only think of afterwards is "Surely it cant be this complex, can it?" :-) — Russell McMahon, Nov 01 '22 at 11:23
Your second Occam's Razor link is dead. Interesting site :-). I wondered what sort of areas you were involved in. That makes some sense of your approach :-). — Russell McMahon, Nov 01 '22 at 18:11
I'm glad you figured out to turn off the water before removing the big honking nut. — Mark Ransom, Nov 01 '22 at 21:18

score 26 · Answer 1 · answered Oct 30 '22 at 22:21

26

Turns out the two smaller "threaded" bolts are actually springs. Red herrings.

Luckily my architect remembered the (discontinued) line "Brizo Quiessence" and was able to find the installation manual for the model 6514521.

Which showed me (facepalm) two more pop-off screw covers on the sides of the faucet (I only looked at front and back). Removing those allowed me to pull off the entire faucet, and thus exposed the two screw heads for the large threaded rods. That's all it took, tightening those from above.

answered Oct 30 '22 at 22:21

Phrogz

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I said it would be subtle. The folks that design these things have some sort of fixation with making it non-obvious! Toast to your architect for getting the right documents! – Ecnerwal Oct 30 '22 at 22:25
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How is it that those little pop-offs weren't blindingly obvious? – Mark Ransom Nov 01 '22 at 21:22

score 8 · Answer 2 · answered Oct 30 '22 at 17:49

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The implication of what you found is that the above counter trim must be removable to expose a part of the bolt that can be tightened. It will, of course, be subtle as to HOW it's to be disassembled unless you can sort out the make and model of faucet to refer to documentation.

answered Oct 30 '22 at 17:49

Ecnerwal

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And reverse image search hasn't come up with anything useful, for me, anyway. All the similar ones I found have a perfectly normal nut to tighten below the countertop. – Ecnerwal Oct 30 '22 at 17:57
See updated question; it's a Brizo, so I'm getting closer. Thanks for the idea! – Phrogz Oct 30 '22 at 18:07
Huh. the closest Brizo I can find (presumable it's discontinued?) has a completely different mounting arrangement. Turn the water off before you attack that nut - it may be more about cartridge replacement than not, and that could cause a large leak if so. Or try contacting the manufacturer? – Ecnerwal Oct 30 '22 at 18:18
You were correct; it was only for cartridge replacement, with nothing related to mounting. The struggle continues. At least I now have a 375mm crescent wrench that can open to 2" gaps :p – Phrogz Oct 30 '22 at 21:12

score 2 · Answer 3 · answered Oct 30 '22 at 19:05

I can rest assure you the valve came in one pice, and did not need to be disassembled to be installed.

You do not have to disassemble the valve to remove it.

The installer first installed the two flanges. Using the bigger bolts screwed from the top, without valve in place.

Then the valve with the two smaller blots was inserted. The smaller bolts were screwed (tightened) to the lover flange from underneeth.

To tighten the valve and the flange, remove the smaller bolts form underneath. Then pull the valve up. You might have to disconnect the water hoses.

Tighten the flanges from the top.

Insert the valve and tighten it with the smaller nuts from underneeth.

Your assurance is correct; disassembling the valve did not provide access to anything related to mounting. I will now endeavor to "remove" the smaller bolts. If you've any advice on how to do so, I welcome it. I'm going to endoscope a bit more, but a pair of pliers grabbing the threaded bolt seems the only option. — Phrogz, Oct 30 '22 at 21:15

How do I tighten this bathroom faucet?

3 Answers3