TOMOON RV Toilet Seal Replacement 2-Pack for Dometic 300/310/320 — OEM-fit Rubber Ball Valve Gasket, Leak & Odour Fix

TOMOON 2-pack RV toilet seal is a direct, high-durability replacement for Dometic 300/310/320 toilets (Part #385311658) designed to stop leaks and reduce odors.

If your Dometic 300, 310 or 320 toilet shows leaks, poor valve closure, or unpleasant smells, swapping the worn ball valve gasket is a fast, cost-effective fix. These TOMOON seals are molded to match OEM dimensions so you can replace the failed part without modifications. The kit includes two identical seals so you can install one and keep the other as a spare for road repairs or next-season maintenance.

How quickly can I replace the old seal?

Installation is straightforward and requires no specialty tools. Most users finish the swap in about five minutes by following simple steps: shut off water, remove the old gasket, clean the contact area, and press the new seal into place. The design seats easily to create an immediate tight closure.

• Typical install time: ~5 minutes
• No tools required for standard replacement
• Includes two seals—one installed, one spare
• Instructions align with OEM part fitment

Will these seals stop leaks and odor without modifications?

Yes — TOMOON seals are custom-sized for Dometic 300/310/320 toilets and match Part #385311658, eliminating the need to alter the toilet. The high-grade rubber formulation maintains a snug fit to help prevent water seepage and reduce odor migration that comes from degraded gaskets. Proper seating and occasional lubrication help sustain the tight seal.

• Precise match to OEM dimensions (Part #385311658)
• High-grade rubber resists deformation and wear
• Helps prevent water leakage and scent escape
• Works immediately after installation when seated correctly

How does the material perform in different climates and terrains?

The seals are formulated for flexibility and resilience, so they stay pliable in cold weather and resist cracking from vibration or movement. That makes them suitable for seasonal camping, off-road travel, and long-haul trips where repeated flexing can stress lesser materials. Regular maintenance, such as applying a thin silicone lubricant, will extend the part’s service life.

• Maintains flexibility at low temperatures
• Resists abrasion and compression set from bumpy roads
• Recommended occasional silicone lubrication for longevity
• Designed for long-term seasonal use and travel

Why buy a 2-pack instead of a single seal?

Keeping a spare seal onboard prevents downtime and emergency trips to the store when a gasket fails on the road. The 2-pack offers value and convenience: install one now and stow the second as an immediate replacement if the installed part wears out. This approach reduces the risk of being stranded with a non-sealing toilet while traveling.

• One ready-to-install, one kept as backup
• Cost-efficient compared with single replacement purchases
• Prevents unexpected service interruptions during trips
• Compact storage—easy to carry onboard

Who is this for: RV owners and repair-minded campers who use Dometic 300, 310 or 320 toilets and want a reliable, OEM-matching replacement for Part #385311658. It’s ideal for travelers who prefer to perform quick DIY maintenance, fleet managers who maintain multiple units, and anyone preparing their rig for seasonal use or off-grid trips. Not compatible with Dometic 210/510 models or unlisted toilets—confirm your model before ordering.