Introduction
This manual provides comprehensive instructions for the installation, operation, maintenance, and troubleshooting of your Fluidmaster 5401GBP4 3-inch Toilet Flapper. Designed for durability and performance, this flapper is a direct replacement for Glacier Bay 3-inch flush valve toilets and is also suitable for other models, including American Standard Cadet 3.
The Fluidmaster 5401GBP4 is constructed from corrosion-resistant materials with a durable silicone seal, ensuring long life and efficient water usage for 1.28 HET and 1.6 GPF toilets.
Product Overview

Figure 1: The Fluidmaster 5401GBP4 3-inch Toilet Flapper. This image shows the red flapper with its attached chain and black float.

Figure 2: Packaging for the Fluidmaster 5401GBP4, highlighting its universal 3-inch adjustable design and silicone seal.
Setup and Installation
Follow these steps for quick and easy installation of your new Fluidmaster 3-inch toilet flapper.
- Turn Off Water Supply: Locate the water supply valve behind or near the toilet and turn it clockwise until the water flow stops.
- Flush Toilet: Flush the toilet to empty the tank. Hold the handle down to ensure as much water as possible drains from the tank.
- Remove Old Flapper: Disconnect the old flapper's chain from the flush lever. Unhook the old flapper from the overflow tube posts or remove it from the flush valve base, depending on its design.
- Install New Flapper: Position the new Fluidmaster 5401GBP4 flapper over the flush valve opening. Hook the two ears of the flapper onto the posts at the base of the overflow tube. Ensure the flapper sits flat and securely over the flush valve opening.
- Attach Chain: Connect the flapper's chain to the toilet's flush lever. Ensure there is a slight amount of slack (about 1/2 inch to 1 inch) in the chain when the flapper is closed. Too much slack will prevent a full flush; too little slack may prevent the flapper from sealing properly.
- Adjust Flapper (if necessary): The 5401GBP4 features an adjustable dial. If your toilet is a 1.28 GPF or 1.6 GPF model, you may adjust the dial to optimize water usage and flush performance. Refer to the markings on the flapper for guidance.
- Restore Water Supply: Turn the water supply valve counter-clockwise to restore water to the toilet tank. Allow the tank to fill.
- Test Flush: Flush the toilet several times to ensure the flapper seals correctly and the toilet flushes efficiently without running. Make any necessary chain adjustments.

Figure 3: Diagram showing the Fluidmaster 5401GBP4 flapper installed inside a toilet tank, connected to the flush lever.
Operating Instructions
The Fluidmaster 5401GBP4 flapper operates automatically as part of your toilet's flushing mechanism. When the toilet handle is pressed, the flush lever lifts the flapper, allowing water to flow from the tank into the bowl for flushing. Once the tank is sufficiently empty, the flapper's weight and the water pressure from the refilling tank cause it to return to its sealed position over the flush valve.
The adjustable dial on the flapper allows for fine-tuning of the flush volume. This feature helps optimize water usage for both 1.28 gallons per flush (GPF) and 1.6 GPF toilets, ensuring efficient performance while conserving water.
Maintenance
Regular maintenance helps ensure the longevity and optimal performance of your Fluidmaster 5401GBP4 flapper.
- Periodic Inspection: Periodically inspect the flapper for signs of wear, cracking, or deterioration, especially around the silicone seal. The durable silicone seal is designed for long life, but extreme water conditions or age can affect any component.
- Cleaning: If mineral deposits or debris accumulate on the flapper or the flush valve seat, gently clean them with a soft brush and a mild, non-abrasive cleaner. Ensure no residue is left that could interfere with the seal.
- Chain Check: Verify that the chain remains properly connected to both the flapper and the flush lever, and that it has the appropriate amount of slack.
The flapper's solid construction from corrosion-resistant materials contributes to its long-term reliability.
Troubleshooting
Here are common issues and their solutions for your toilet flapper:
| Problem | Possible Cause | Solution |
|---|---|---|
| Toilet runs continuously or cycles on and off. | Flapper not sealing properly; chain too short; debris on flush valve seat; worn flapper. |
|
| Weak or incomplete flush. | Chain too long; flapper not opening fully; water level too low. |
|
| Flapper detaches from overflow tube. | Improper installation; excessive force. |
|
Specifications
| Attribute | Detail |
|---|---|
| Model Number | 5401GBP4 |
| Brand | Fluidmaster |
| UPC | 039961011756 |
| Size | 3 inches |
| Color | Red |
| Material | Rubber (Silicone Seal) |
| Item Weight | 3.2 ounces |
| Product Dimensions | 3 x 1 x 2 inches |
| Compatibility | Glacier Bay 3-inch flush valve toilets, American Standard Cadet 3, and other compatible models. |
| Water Usage | Suitable for 1.28 HET and 1.6 GPF models. |
Warranty Information
The Fluidmaster 5401GBP4 3-inch Toilet Flapper includes a standard 5-year warranty. This warranty covers defects in materials and workmanship under normal use and service.
For warranty claims or further details, please retain your proof of purchase and contact Fluidmaster customer support. Do not attempt to repair the product yourself as this may void the warranty.
Customer Support
If you have any questions, require assistance with installation, or need to troubleshoot an issue not covered in this manual, please contact Fluidmaster customer support. Visit the official Fluidmaster website for contact information and additional resources.
You can find more information and support at the Fluidmaster Store on Amazon.





