Dometic 385311658

Flush Ball Seal Kit

Dometic 385311658 is the flush ball seal kit for the 310 Gravity-Flush Toilet. The rubber seal the flush ball closes against at the bottom of the bowl. It is what keeps water sitting in the bowl between flushes, and it is the part that fails when the bowl drains dry.

Which models this fits

  • 310 Gravity-Flush Toilet

    Verified against Dometic Parts List, 310 Gravity-Flush Toilet (P/N 600346224, Rev. 01/10).

We have not verified 300, 301, 311, 320, 321. Retailers commonly list this seal as fitting the whole 300/310/320 range. Dometic’s parts list that we hold covers the 310 only. Check your model ID label before ordering.

How to tell which one you have

Dometic puts the model ID label on the toilet base, underneath the water valve. Read the model number off that label rather than guessing from the shape of the toilet.

Is this part still current?

Yes. Dometic still lists 385311658 on its current parts list.

Where to get this part

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Check this before you order

  • Read the model number from the label on the base, under the water valve.
  • Confirm your toilet is a Dometic or SeaLand gravity-flush unit, not a Thetford.
  • If your model is not a 310, check the seal against your own model’s parts list first.

Before you start the job

Dometic notes that mineral deposits from hard water build up on the flush ball and seal and cause a slow leak. Cleaning the ball and seal sometimes fixes the leak without a new part.

Where our information comes from

We work from the manufacturer’s own documents. We have not installed this part and we do not test parts in a shop.

Last checked 2026-08-24.