[juzdownunder]

I have a fluidmaster 400A, and there's a leak started where the water inlet pipe connects to the threaded shank of the fluidmaster unit.

I took out the old fixed steel pipe running from the toilet tap into the shank, and replaced it with a new, braided steel flexible pipe with the built in cone washers.

After connecting the coupling nut of the braided pipe to the fluidmaster shank, being careful not to overtighten, it still leaks badly when i turn the tap back on. I tried tightening the coupling nut to the shank more, but it gets to the stage where any more tightening make the shank turn, throwing the float cup out of alignment in the cistern tank. I even tried using teflon tape on the thread of the shank before re-tightening.

It's still leaking. To be sure it's the coupling nut/shank connection, I turned the tap off, and filled the cistern with a bucket, no leaks. So it's not the shank washer inside the toilet that's leaking. The leak only happens when i turn the water back on.

I'm using terminology from this manual by the way: http://www.fluidmaster.com/downloadable/download/sample/sample_id/248/

Any ideas?

 

[Lightfoot]

Since it's a plastic part, you might also see if there is any plastic flashing that needs trimming off where the part was molded. Sometimes plastic parts come out kinda rough, with a ridge where it's supposed to be smooth. That could cause a leak as well if the rubber cone is not seating good against a ridge. Well that, and make sure it's not cross threaded. That's all i got:thumbsup:

 

[TarheelTerp]

I have a fluidmaster 400A, and there's a leak started where the water inlet pipe connects to the threaded shank of the fluidmaster unit.

I took out the old fixed steel pipe running from the toilet tap into the shank, and replaced it with a new, braided steel flexible pipe with the built in cone washers.

Is the 400A also new?
Did the leak develop after a new 400A was installed?

 

[juzdownunder]

Is the 400A also new?
Did the leak develop after a new 400A was installed?

No it's an old system, sorry, I should have mentioned that. I've not changed anything in this toilet since I bought the house it's in 9 years ago. I should have said my ballcock system is 'like' the 400A...it's a fluidmaster, but probably an older model than the 400A.

The leak started a week or so ago, and has gotten a little worse day by day. So it's something that's gone wrong after a long time, and replacing the old rigid steel pipe with flexible steel braid hasn't helped fix it.

I would think it's the seal on the fluidmaster itself, other than the fact the toilet doesn't leak when the cistern is full, and the inlet tap is turned off. It's only with the tap on that the leak happens.

 

[TarheelTerp]

No it's an old system, sorry, I should have mentioned that.
The leak started a week or so ago, and has gotten a little worse day by day.

Gotcha. You gave it a fair shot but now it's time to replace the 400A.
Do the flapper thing at the same time.

While you're at the store buying this kit buy a second and stash that near the other bathroom. You're likely to be using it soon.

 

[juzdownunder]

Gotcha. You gave it a fair shot but now it's time to replace the 400A.
Do the flapper thing at the same time.

While you're at the store buying this kit buy a second and stash that near the other bathroom. You're likely to be using it soon.

Yep, reckon you're right, can't think what else could be the problem, perhaps the shank has cracked or worn over the years. Doesn't look so upon visual inspection but I guess that doesn't mean much in the world of water pressure.

No issues on the other bathroom, it was only added to the house two years ago. Plus it's a slimline Caroma jobbie, whole 'nuther world in the cistern of that thing!

 

[ben's plumbing]

Yep, reckon you're right, can't think what else could be the problem, perhaps the shank has cracked or worn over the years. Doesn't look so upon visual inspection but I guess that doesn't mean much in the world of water pressure.

No issues on the other bathroom, it was only added to the house two years ago. Plus it's a slimline Caroma jobbie, whole 'nuther world in the cistern of that thing!

my guess has small crack.....had 4-5 in the last month from ace hardware......:yes:

 

[juzdownunder]

Ok, new fluidmaster 400UK from Masters (AUD$19) installed, and it seems to have fixed the problem.

The only issue during installation was the nut under the tank, that pulls the sealing washer into place. The instructions are very specific this should be 'hand tighten only', suggesting overtightening might crack the cistern.

I hand tightened, but as soon as the tank started filling I was getting a lot of water out of that nut. I took it all apart again thinking i hadn't seated the sealing washer correctly, and noticed that on the inside of the cistern, just at the edge of the hole for the shank is what appears to be a nub of porcelain, like an inconsistency when they made it. About the size of half a popcorn kernel. Not sure that was causing the problem, but certainly doesn't look like it should be there.

Anyway, put it all back together, hand tighten only, major leakage. So grabbed the wrench and gave it a small turn, helped....turned again a bit more agressively....leak stopped..no cracked cistern. Hope this works.

Cheers for the advice all,

Juz.

 

[Yoyizit]

I alway use teflon paste or tape for all connections.

 

[juzdownunder]

I alway use teflon paste or tape for all connections.

I thought about that but the instructions and the box all have "Do not use plumber's goop" written all over them.

I'm not sure the tape would help here as the leak appears to be past the rubber seal, not along the thread.