Five toilet repair kits from Fluidmaster and Korky, compared by what each one fixes (fill valve, flapper or flush valve) and the toilets it fits.
Please note: Product availability and information are based on our research at time of writing and are subject to change. Always check Amazon for the latest details before purchasing. Our assessments are research-based. We compared manufacturer pages, instruction sheets and Amazon listings, and we have not installed these kits ourselves. Where a detail comes only from a listing, we say so.
A running, noisy or slow-filling toilet usually comes down to one of three parts inside the tank: the fill valve that refills it, the flapper that seals the flush opening, or the flush valve the flapper sits on. The first two are replaced without removing the tank; the flush valve is not. The five kits below cover those repairs in different combinations, so the table starts with what each kit fixes and which toilets it fits, then the full reviews follow.
| Kit and role | Repair need and toilet fit (maker wording) | Amazon link |
|---|---|---|
| Fluidmaster 400A Kit, 2-Pack (listing model K-400A-5004) Two Fill-Valve-and-Flapper Kits |
Running, noisy or slow-filling toilet: fill valve and flapper 2 in flush valve; 3.5 gpf or more, pre-1994 toilets, per Fluidmaster; no tank removal |
Check Price |
| Fluidmaster 400H PerforMAX, 2-Pack (listing model 400H-5003) Two Fill Valves, No Flappers |
Fill valve only, two toilets or a spare 1.28 and 1.6 gpf best, pre-1994 3.5 gpf usable, per Fluidmaster; no tank removal |
Check Price |
| Fluidmaster 540AKR 3-Inch Flush Valve Kit (540AKRP5) 3-Inch Flush Valve Replacement |
Cracked or leaking 3 in flush valve; no fill valve 3 in flush valve toilets; tank comes off the bowl |
Check Price |
| Korky QuietFILL 818 Kit (818BP) Fill Valve and 2-Inch Flapper Kit |
Running, noisy or slow-filling toilet: fill valve and flapper 2 in flush valve; most 2-piece and 1-piece toilets, per Korky; no tank removal |
Check Price |
| Korky QuietFILL Platinum Complete Kit (4010MP) Complete Kit for 2-Inch Flush Valves |
Fill valve, flapper and 2 in flush valve in one kit 2 in flush valve toilets; tank comes off the bowl |
Check Price |
Fit notes are each maker’s own wording, not our measurements. Price tiers appear in the product boxes below and follow the site’s rule, in which $ is under $20, $$ is $20 to $60 and $$$ is over $60; offers and sellers change. Two of the five are 2-packs: the Fluidmaster 400A pack holds two fill-valve-and-flapper kits, and the Fluidmaster 400H pack holds two fill valves and no flappers.
✏️ Our Take
Match the kit to the failed part and to the toilet. A fill valve and flapper kit covers the common running or noisy toilet on a 2-inch flush valve; the two flush valve kits are for a cracked or leaking flush valve, one for 2-inch and one for 3-inch openings, and both mean lifting the tank off the bowl. Fluidmaster and Korky both publish instruction sheets and warranty terms, which we link below; measure the flapper or flush valve opening before you order, and follow the maker’s sheet for the install.
IN THIS GUIDE
Two Fill-Valve-and-Flapper Kits
The Amazon listing behind this link is the 2-pack: two kits, each with a Fluidmaster 400A fill valve and a solid-frame 2-inch flapper, according to the listing’s own contents line. That matches Fluidmaster’s 400CR kit, whose instruction sheet lists a fill valve, a flapper, a shank washer, a locknut, a refill tube and a refill clip; the listing’s model number, K-400A-5004, appears in no Fluidmaster document, so the match rests on the described contents. Fluidmaster lists the 400A’s height adjustment as 9 to 14 in and calls the 400A-plus-2-inch-flapper pairing the combination for toilets of 3.5 gallons per flush or more made before 1994; for toilets using 1.6 gallons or less it points to a different kit.
Installation needs no tank removal; Fluidmaster’s instruction sheet lists scissors and a sponge, and it is linked under Manufacturer Sources. Fluidmaster says the 400A does not fit Glacier Bay or Niagara flapperless toilets or side-entry valves, and that in-tank drop-in cleaners void the warranty. Fluidmaster’s warranty page lists five years for the 400CR kit (Fluidmaster warranty details). The single kit is a separate Amazon listing, so check the pack count before you order; when we checked, Amazon.com sold this pack with a 30-day return window. This review does not cover installation.
Fluidmaster
Best for: Two Fill-Valve-and-Flapper Kits
Two fill-valve-and-flapper kits: Amazon's listing for this link is the 2-pack and says each kit includes a 400A fill valve and a solid-frame 2-inch flapper, which matches Fluidmaster's 400CR kit.
Two Fill Valves, No Flappers
This pack is two 400H PerforMAX fill valves; no flappers are included, so it suits a fill valve that has failed on two toilets, or one repair plus a spare. Fluidmaster’s current 2-pack page lists a 9 to 14 in height adjustment, says the valve is best for 1.28 and 1.6 gallon-per-flush toilets and also usable with pre-1994 3.5 gallon toilets, and says the shank washer comes pre-installed. The 2-pack page does not state flush valve sizes; Fluidmaster’s 400H shop page says the valve fits 2-inch and 3-inch flush valve toilets, so confirm your tank before ordering. The listing’s model number, 400H-5003, does not appear on Fluidmaster’s page.
The height figure here is the one on Fluidmaster’s 2-pack page, 9 to 14 in; a different Fluidmaster kit page for a 400H-based kit gives 10 to 15 in, which is a difference between Fluidmaster’s product pages, not evidence that this pack has two ranges. The seven-year warranty is also the 2-pack page’s figure (Fluidmaster warranty details); the older instruction sheet linked from that page prints five years. Check the instructions and warranty supplied with your exact pack. Installation needs no tank removal, and Fluidmaster lists a sponge, bucket and towel, with scissors optional; the instruction sheet is linked under Manufacturer Sources. When we checked, Amazon.com sold it with a 30-day return window. This review does not cover installation.
Fluidmaster
Best for: Two Fill Valves, No Flappers
Two Fluidmaster 400H PerforMAX fill valves and no flappers.
3-Inch Flush Valve Replacement
The 540AKRP5 does a different job from the fill valve and flapper kits: it replaces the flush valve assembly, the overflow tube and seat at the bottom of the tank, on a toilet with a 3-inch flush valve. Fluidmaster’s 540AKR page links this exact Amazon listing, and lists an adjustable flush valve, a 3-inch flapper, a tank-to-bowl gasket, and bolts, washers and nuts in the kit; it says the overflow tube height adjusts up or down and that the kit fits Toto, American Standard and other common 3-inch flapper toilets. There is no fill valve in the kit.
Installation requires removing the tank: Fluidmaster’s instruction sheet, linked under Manufacturer Sources, has you unbolt the tank and lift it off the bowl, so it takes longer than a fill valve swap; the sheet lists no tools. Measure first: Fluidmaster’s sizing guide says a flapper about 3 in wide means a 2-inch flush valve and one about 4 in wide means a 3-inch flush valve. Fluidmaster lists a five-year warranty for the 540AK/AKR (Fluidmaster warranty details). When we checked, Amazon.com sold it with a 30-day return window and showed limited stock. This review does not cover installation.
Fluidmaster
Best for: 3-Inch Flush Valve Replacement
Fluidmaster's 540AKR 3-inch flush valve kit, sold as 540AKRP5: an adjustable flush valve, a 3-inch flapper, a tank-to-bowl gasket, and bolts, washers and nuts.
Fill Valve and 2-Inch Flapper Kit
Korky’s 818 kit, sold as 818BP, holds a 528 QuietFILL fill valve, a 2001 2-inch flapper, a refill tube with metal clip, installation hardware and instructions, per Korky’s page. Korky says the QuietFILL valve is quieter than other fill valves and was the quietest in its own lab testing; those are Korky’s claims, and it publishes no noise figure. Korky describes the kit as universal for all brands, with a twist-lock adjustment to fit most 2-piece and 1-piece toilets, and the flapper fits a 2-inch flush valve opening. Korky publishes no height adjustment range for this valve and no gallons-per-flush rating for the kit.
Installation needs no tank removal; Korky’s instruction sheet lists a bucket, with a wrench, sponge and towel as possible needs, and it is linked here and under Manufacturer Sources. Korky lists a five-year warranty from the date of purchase, and its instruction sheet excludes damage from over-tightening the mounting nut and from in-tank drop-in cleaners (Korky 818 instructions and warranty). When we checked, Amazon.com sold it with a 30-day return window. This review does not cover installation.
Korky
Best for: Fill Valve and 2-Inch Flapper Kit
Korky's 818 kit: a 528 QuietFILL fill valve, a 2001 2-inch flapper, refill tube with metal clip and installation hardware.
Complete Kit for 2-Inch Flush Valves
The 4010MP is the broadest kit here. Korky lists a 528MP fill valve, a 100 2-inch flapper, a 4030 adjustable 2-inch flush valve with a tank-to-bowl gasket, three bolts with rubber washers, metal washers and nuts, and instructions. Two height ranges apply and they are different parts: Korky lists the 528MP fill valve as adjusting from 8-1/2 to 14 in, and the 4030 flush valve’s overflow tube as adjusting from 7 to 11-1/2 in without cutting. The 100 flapper is listed for 1.28, 1.6, 3.5 and 5 gallon-per-flush toilets, and the kit fits a 2-inch flush valve opening only; a 3-inch flush valve needs the Fluidmaster kit above.
Installation requires removing the tank: Korky’s instruction sheet, linked here and under Manufacturer Sources, lists a bucket, pencil, ruler, adjustable wrench and slip-joint pliers and has you lift the tank off the bowl to replace the flush valve. Korky lists a five-year warranty from the date of purchase for the 4010MP, with the same exclusions for over-tightening and drop-in cleaners (Korky 4010MP instructions and warranty). When we checked, Amazon.com sold it with a 30-day return window. This review does not cover installation.
Korky
Best for: Complete Kit for 2-Inch Flush Valves
Korky's complete kit for a 2-inch flush valve: a 528MP fill valve, a 100 flapper, a 4030 adjustable flush valve with tank-to-bowl gasket, and bolts, washers and nuts.
A toilet runs when water leaks from the tank into the bowl faster than the fill valve can stop, or when the fill valve will not shut off. A worn flapper lets water trickle past the seal; a worn fill valve runs too long or overfills. A cracked or corroded flush valve leaks at the seat the flapper sits on, and a new flapper alone will not cure it. If you have already narrowed it to one part, our toilet flapper and toilet fill valve reviews cover single parts; our how to fix a running toilet guide walks through the symptoms.
Most of these kits are for 2-inch flush valves; the Fluidmaster 540AKR is for 3-inch. Fluidmaster’s sizing guide uses the flapper: about 3 in wide end to end means a 2-inch flush valve, about 4 in wide means a 3-inch one. The makers’ fit claims differ by product, so read the exact wording: Fluidmaster recommends the 400A-and-flapper pairing for 3.5 gpf or larger toilets made before 1994 and points 1.6 gpf toilets elsewhere, while Korky lists its 100 flapper for 1.28 to 5 gpf toilets and describes its fill valves as fitting most toilets.
The Fluidmaster 400A pack linked here holds two fill-valve-and-flapper kits; the Fluidmaster 400H pack holds two fill valves and no flappers. If a flapper is leaking, the 400H pack alone will not fix it. Check the pack count on the listing before ordering, because single kits are separate listings.
Fill valve and flapper swaps are done with the tank in place; both makers list only hand tools such as a sponge, bucket, scissors or a wrench. The two flush valve kits, Korky’s 4010MP and Fluidmaster’s 540AKR, have you unbolt the tank and lift it off the bowl, so plan more time and a second pair of hands. Both makers say that in-tank drop-in cleaners void the warranty. Follow the sheet packed with your kit, and if the tank bolts are corroded or the porcelain is cracked, a plumber is the safer call.
Sometimes a job is too big for DIY. If you need a licensed plumber in your area, search PlumberArchive.com — the US plumber directory.
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A dye test helps: add a few drops of food coloring to the tank and wait about 15 minutes without flushing. Color reaching the bowl without flushing indicates leakage from the tank; it does not identify the failed component by itself. If the color stays put but the valve keeps running after a flush, or the water sits above the overflow tube, the fill valve is the likelier part. Many people replace both while the tank is open, which is what the fill-valve-and-flapper kits are for.
A fill valve and flapper swap keeps the tank in place and both makers list only hand tools. The two flush valve kits are a bigger job: Korky’s and Fluidmaster’s instructions have you unbolt the tank and lift it off the bowl, then reset and level it. Follow the maker’s sheet for your kit; this review does not cover installation.
The 400A pack holds two kits, each with a fill valve and a 2-inch flapper, per its listing. The 400H pack holds two PerforMAX fill valves and no flappers. If the flapper is the problem, the 400H pack alone does not fix it.
No. Each maker sets its own limits: Fluidmaster recommends the 400A-and-2-inch-flapper pairing for 3.5 gpf or larger toilets made before 1994 and points 1.6 gpf toilets to another kit, and says the 400A does not fit Glacier Bay or Niagara flapperless toilets. The 3-inch flush valve in some Toto, American Standard and Kohler toilets needs a 3-inch flapper or the 540AKR kit. Measure the flapper or flush valve opening and read the maker’s fit wording before ordering.
Start with the failed part and the flush valve size. For a running or noisy toilet on a 2-inch flush valve, the Fluidmaster 400A 2-pack gives two fill-valve-and-flapper kits, which Fluidmaster pairs with pre-1994 toilets of 3.5 gpf or more, and the Korky 818BP gives one fill valve and flapper with Korky’s quieter-fill claim. If only the fill valve has failed on two toilets, the Fluidmaster 400H 2-pack holds two fill valves and no flappers. If the flapper alone is the problem, our guide on how to replace a toilet flapper covers that repair.
If the flush valve itself leaks, pick by opening size and plan on removing the tank: the Fluidmaster 540AKR replaces a 3-inch flush valve and includes no fill valve, and the Korky 4010MP replaces a 2-inch flush valve and adds a fill valve and flapper in the same kit. Whichever you choose, each maker’s instruction sheet and warranty terms are linked above.
Prices and offers may change. Always check Amazon for current prices and return terms.
Kit contents, fit, installation and warranty statements come from these pages and documents; Amazon listings are cited only for listing details such as pack counts and model numbers.
✍️ About This Review
PTR Editorial Team — Product Reviews. We compare manufacturer specifications, installation requirements, compatibility and available product documentation to help homeowners choose suitable tools and parts. For this Review, specifications are sourced from the manufacturer pages and documents listed above, and from Amazon listings where noted. How we review →
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