JAYCO JAY FLIGHT 174BH - Toilet Seal Kit Replacement

JAYCO JAY FLIGHT 174BH – Toilet Seal Kit Replacement

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Complete repair guide for the JAYCO JAY FLIGHT 174BH – Toilet Seal Kit Replacement.

Parts & Tools You’ll Need

Step 1: Diagnose Toilet Seal Failure and Prepare

Begin by identifying whether your toilet has a slow water leak, weak flush, or water pooling around the base. Close the water supply valve to your bathroom and flush the toilet completely to empty the tank. Remove any items stored in your bathroom cabinet and lay down towels beneath the toilet to catch residual water. Check the model number on your Thetford toilet to confirm you have a ball valve system compatible with the Thetford 34120 Toilet Seal Kit. Document the current condition with photos for reference during reassembly.

Step 2: Remove Water Supply and Disconnect Toilet

Locate the water supply line connection at the base of your toilet and use an adjustable wrench to loosen the compression nut, turning counterclockwise until water stops flowing. Have a bucket or towels ready to catch residual water from the line. Next, locate the two bolts securing the toilet base to the RV closet flange on the floor—these typically require a 1/2-inch wrench. Remove both bolts completely, then carefully rock the toilet side-to-side to break the seal created by the RV Closet Flange Wax Ring Seal. Lift the toilet straight up and set it on its side on a protected surface nearby.

Step 3: Access and Remove the Ball Valve Assembly

Locate the ball valve assembly beneath the toilet tank—this is the water control mechanism that regulates flow to the bowl. You’ll see a nut securing the valve to the tank wall, typically requiring a 1-1/8-inch wrench. Turn counterclockwise to remove this nut while holding the valve steady with your other hand to prevent it from spinning. Once the nut is loose, carefully pull the valve assembly straight out from the tank. Place the old valve on your towel and inspect the rubber seals inside for cracks, deterioration, or mineral deposits that confirm replacement is necessary.

Step 4: Install the New Thetford 34120 Seal Kit

Open your Thetford 34120 Toilet Seal Kit package and identify the new rubber gasket, ball valve seal, and stainless steel washers included. Clean the threaded valve hole on the toilet tank with a dry cloth to remove any debris or mineral buildup. Insert the new valve assembly into the tank opening, ensuring the outlet port faces downward toward the bowl channel. Thread the securing nut back onto the valve by hand first, then tighten with your wrench to 18-22 foot-pounds of torque—do not over-tighten, as this can crack the plastic tank. Verify the valve moves freely when you press on the activation lever before proceeding.

Step 5: Replace the Water Valve and Reconnect Supply

If your RV Toilet Water Valve Replacement kit includes a new shutoff mechanism, disconnect the old one from the supply line using a wrench on both the inlet and outlet connections. Install the new water valve following the kit’s orientation diagram, ensuring the flow arrow points toward the toilet. Wrap the male threads with plumber’s thread seal tape (not included) in a clockwise direction—three to four complete wraps—then hand-tighten the compression nut before using a wrench for final snugging. Reattach your water supply line to the new valve outlet, tightening firmly but not forcing. Open the main water valve slightly and check both connection points for drips before proceeding to reinstallation.

Step 6: Reinstall Toilet Base with New Wax Ring

Before lowering the toilet back onto the closet flange, remove the old RV Closet Flange Wax Ring Seal from the flange and scrape away any residual wax or debris with a plastic scraper. Install a fresh wax ring, pressing it firmly into place around the flange opening to create a proper seal. Carefully lower your toilet straight down over the flange bolts, aligning the bolt holes precisely with the openings on the toilet base. Insert and hand-tighten both bolts first, then alternately tighten them with a wrench to 25 foot-pounds of torque, working in a crisscross pattern to ensure even seating. Double-check that the toilet sits level and doesn’t rock side-to-side before moving to the final step.

Step 7: Test All Functions and Verify No Leaks

Slowly open the water supply valve to refill the toilet tank, listening for any unusual sounds or detecting any water pooling around the base or tank. Once the tank is full, press the foot pedal to flush and observe the water flow and seal action—it should be smooth with no hesitation or leaking around the valve. Flush at least three times, checking the floor underneath and around all connection points for any moisture. Leave the toilet idle for 15 minutes, then check again to confirm no slow seeps are developing. If desired, add Camco TST Ultra RV Toilet Treatment to the bowl to restore the trap seal and improve performance.