COMPATIBILITY FIRST · NO INTRO ADS
Replace a compatible toilet tank
TOTO Eco Drake CST744E gravity toilet: replace a complete ST743E 1.28-gpf tank assembly on its sound, securely installed C744E bowl. This conventional two-bolt example uses separate tank-sealing hardware and bowl-mounting hardware.
- CST744E pairs the ST743E tank with the C744E bowl (no T in the bowl number). Confirm the exact model, flush volume and matching finish before ordering; bolt spacing alone does not establish compatibility.
- Use the specified 9BU024E tank-to-bowl gasket and TSU01D tank mounting kit, or the current genuine parts TOTO specifies for the exact tank. The illustrated kit has two bolts, two rubber washers, four metal washers and four metal nuts.
- Each bolt is sealed to the tank before the tank is lowered onto the bowl: rubber under the bolt head inside, then a metal washer and sealing nut beneath the tank. A second metal washer and mounting nut secure it below the bowl.
- The three designated ceramic contact points are supports, not a third bolt. Use a complete replacement tank with its factory-set internal parts and new, undamaged matched gasket/hardware; verify the contents before disconnecting anything.
The animation shows the flapper-equipped ST743E version. Some ST743E tanks use a tower; the exact tank’s part diagram and supplied hardware instructions control. Preserve correctly assembled factory internals, and follow the instructions for your exact revision if they differ.
01 / DIAGNOSE BEFORE BUYING
Confirm the repair fits the problem.
- Identify the tank and bowl before ordering. Verify the complete pairing with TOTO; a brand name or matching bolt spacing alone is insufficient.
- A running toilet does not establish that its ceramic tank needs replacement. Check fill/flush mechanisms first. Dry the exterior and locate an external leak; a connection or gasket may be the repair.
- Cracked china must not be patched and returned to service. Isolate the water and arrange safe removal; sharp or unstable breakage needs professional handling.
This procedure does not cover
- One-piece, pressure-assisted, concealed-cistern, wall-hung and electronic toilets
- Other tank/bowl combinations, including a similar-looking tank with different flush volume or bolt pattern
- Bare ceramic shells requiring transfer of internal mechanisms
- Cracked bowl, unstable toilet, damaged ceramic mounting surfaces, or persistent base leaks
02 / COMPATIBILITY & PREPARATION
Have the matching parts ready.
- Adjustable wrench, flat screwdriver and correctly fitting tank-nut tool; keep tools off the plastic supply coupling
- Small level
- Bucket, sponge, towels, gloves and eye protection
- Padded resting surface and a helper for heavy/awkward lifting
- Exact ST743E complete tank assembly, new matched 9BU024E gasket and TSU01D mounting kit (or current TOTO-specified replacements), compatible new supply connector when required
These checks are for your use. They do not certify compatibility and are not saved.
03 / STRAIGHT TO THE REPAIR
See how the parts move.
Read the narration transcript
Shut off the toilet supply, flush, and check that the tank stays empty. Sponge out the remaining water. If it refills, stop and arrange upstream isolation. This example uses a two-bolt TOTO Eco Drake. Confirm the exact tank and bowl pairing shown; similar-looking tanks may not fit. Set the lid on padding. Catch drips while disconnecting the supply. Support the tank, remove both lower mounting nuts and washers, and lift it away with help. Stop for seized hardware, cracked china, a rocking bowl, or pipe movement. Clean and inspect the bowl’s mounting surface. Support the replacement tank on padding. Check its factory valve nuts, then seat the new round gasket over the flush-valve nut. Put a rubber washer under each bolt head inside the tank, and a metal washer and sealing nut underneath. Hold each bolt centered. Tighten its nut finger-tight, then one half-turn with a wrench, as this model specifies. Align both bolts and the gasket, then lower the tank straight onto the bowl with help. Fit another metal washer and nut below each bowl mounting hole. Finger-tighten and check level, then tighten evenly until the tank meets all three molded support points. Do not overtighten. Flush the supply into a bucket as directed. Close it again, connect the tank end finger-tight without twisting, then restore water slowly. Check the marked waterline and flush several times. Inspect the supply, bolt areas and tank joint during filling and flushing, then again at rest. If anything leaks, shut the water off and correct it before use.
04 / THE PROCEDURE
Work gently. Check as you go.
- Shut off and drain Close the toilet supply, flush, and verify that the tank does not refill. Sponge it dry. If isolation fails, stop and arrange working upstream isolation before disconnecting anything.
- Protect and disconnect Lift the lid onto padding. Place a bucket below the supply connection and disconnect the tank end without twisting the fill valve or stressing the wall pipe. Stop if hardware is seized.
- Lift the old tank Support the tank while removing the two lower mounting nuts and metal washers underneath the bowl ledge. Leave each bolt’s separate sealing nut and washer under the tank in place. With help, lift vertically clear of the bowl. Never pry against the ceramic or lift a whole toilet by its tank.
- Inspect the mating surfaces Remove the old connection gasket, clean the contact area gently, and inspect the bowl ledge and replacement tank. Stop for cracks, chips on sealing/mounting areas, instability, or unverified fit.
- Check the tank and fit the gasket Rest the tank on padding. Preserve securely installed factory valve nuts. Only if loose, the TOTO manual specifies hand-tight plus 1/4 turn for the smaller fill-valve nut and hand-tight plus 1/2 turn for the larger flush-valve nut. Spread the new matched ring gasket over the flush-valve nut toward the tank bottom; the manual allows a slight gap. Do not confuse this gasket with the floor wax ring.
- Seal both bolts to the tank Put one rubber washer directly under each bolt head inside the tank. Pass the bolt through its tank hole, then add one metal washer and one sealing nut outside beneath the tank. Keep the bolt centered; tighten that nut finger-tight, then another 1/2 turn with a wrench. Repeat on the second bolt. No metal washer goes between the bolt head and its rubber seal.
- Lower, level and secure Align the gasket and both bolts with the bowl openings, then lower the tank without rolling or trapping the gasket. Below the bowl ledge, fit the remaining metal washer and mounting nut on each bolt. Start finger-tight and check level, then tighten both sides equally in small increments until the three designated ceramic contact points meet the bowl. These front-left, front-right and rear-center supports are not bolt positions. Stop at the specified contact; do not keep tightening to close other molded gaps or crush the ceramic.
- Reconnect and test With the disconnected supply end controlled over a bucket, briefly flush the line to clear debris, then shut it off again before connecting. Keep the hose free of strain or kinks. The connection to the tank’s plastic fill-valve shank is finger-tight only; do not use a wrench on it. Follow the connector instructions for its other end. Restore water slowly, check the marked tank waterline, and flush several times. Inspect the supply, bolt areas and tank-to-bowl joint while filling, flushing and at rest. Stop and isolate for any leak.
05 / VERIFY THE RESULT
Check operation and every disturbed joint.
- Tank remains level and stable at the three designated support contacts, with both bolts correctly sealed and secured; no extra tightening past contact.
- Tank fills to its own marked line and filling stops.
- Several flushes complete normally; dry tissue at each external joint stays dry during and after refilling.
- Recheck for seepage after the toilet has stood; external leaks require isolation and correction before use.
- Do not use in-tank cleaning products, particularly chlorine-containing cleaners; TOTO warns that they can damage fittings and cause leaks.
KNOW YOUR LIMITS
Stop and get qualified help when…
- Water continues to enter after shutoff
- Corroded/seized hardware, pipe movement, or an inaccessible connection
- Cracked china, damaged sealing surfaces, a rocking bowl, or uncertain tank/bowl match
- Leakage that persists after correct assembly; never compensate by progressively crushing ceramic
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MANUFACTURER REFERENCES
Sources & scope.
Written instructions use the manufacturer references below. The 3D illustration is not a manufacturer certification or a substitute for the instructions supplied with your exact model.
- TOTO Eco Drake CST744E specification: ST743E tank + C744E bowl, dimensions and rough-in
- TOTO installation manual 0GU048Z: two-bolt hardware, gasket, three contact points and supply connection
- TOTO CST744E parts drawing: 9BU024E tank gasket, TSU01D mounting kit and internal-part variants
Checked October 15, 2026. These are information links, not affiliate links. We do not sell tools or parts.