Product Description

Pair of Gearbox Gear Oil Drain / Fill Plug Seals for Mercury Mariner Outboards

Premium-quality aftermarket gearbox gear oil drain and fill plug seal gaskets for selected Mercury and Mariner outboard engines.

Supplied as a pair of 2 seals, ideal for replacement when carrying out a gearbox / lower unit gear oil change.

These seals fit selected Mercury and Mariner gearcases using 3/8"-16 drain/fill screws and replace the commonly used Mercury seal 12-191833 / 191833.

Package Contains

2 x Gear Oil Drain / Fill Plug Seal Gaskets

Fits Selected Mercury & Mariner Outboards

Suitable for a wide range of selected Mercury and Mariner outboard gearcases using the corresponding 3/8"-16 gear oil drain/fill screws.

These seals are used across numerous Mercury/Mariner engine families, so compatibility should be confirmed using the original part number or drain/fill screw specification, rather than horsepower alone.

Important

Some Japanese-manufactured Mercury/Mariner outboards use different metric drain plugs and gaskets, so this seal should not be assumed to fit every Mercury or Mariner outboard.

Replaces Mercury / Mariner Part Numbers

12-191833
12-19183-3
12-19183-2
12-19183
12-191832
191833
191832
19183
12-20260
20260

These numbers appear within the same Mercury drain/fill seal/washer replacement family.

OEM part numbers are used for identification and reference purposes only.

Product Features

Pair of 2 seals
Gearbox oil drain plug gasket
Gearbox oil fill plug gasket
Gearcase drain screw seal
Gearcase fill screw seal
Lower unit oil drain washer
For selected Mercury outboards
For selected Mariner outboards
Suitable for corresponding 3/8"-16 drain/fill screws
Marine-grade quality aftermarket part
Manufactured to OEM specifications
Helps prevent gear oil leakage
Helps prevent water entering the gearbox
Ideal for routine gearbox oil servicing
New
UK stock

Important – GEARBOX / GEAR OIL Seals

These seals are for the GEARBOX / LOWER UNIT gear oil drain and fill plugs.

They should not be confused with an engine oil sump / drain plug gasket used on a 4-stroke engine.

These seals are designed for the gearcase gear oil drain/fill screws.

Why Replace Both Seals?

When changing your outboard gearbox / lower unit oil, the drain and fill/vent screw seals should be inspected and replaced as required.

A damaged, flattened or deteriorated seal can allow:

Gear oil to leak from the gearbox
Water to enter the lower unit
Contamination of the gearbox oil

Mercury parts references show applications where two 191833 seals are required per gearcase assembly, supporting a two-seal service pack.

Important – Please Check Compatibility

Please do not order by appearance or engine horsepower alone.

Before purchasing, please check:

Engine is Mercury or Mariner
Original gasket / seal part number
Gearbox drain/fill screw type
Drain/fill screw uses the corresponding 3/8"-16 arrangement
Engine model and serial number if unsure

For the safest identification, confirm that your engine requires the 12-19183 / 191833 family of seals.

If the part looks the same as yours, this does not always mean it is the correct one for your outboard.

If you are unsure, please send us your engine model and serial number before purchasing and our technical team will be happy to check compatibility.

Why Buy From SSI Marine?

Marine-grade aftermarket & OEM-spec parts
Workshop-tested products
More than 10 years supplying outboard parts
UK stock
Same working day dispatch before 1 PM Monday–Friday
Royal Mail Tracked 24
Technical support from experienced outboard specialists
Collection available from Leigh, Greater Manchester
Workshop open Monday–Friday, 9 AM–5 PM

Mercury Mariner Outboard Gearbox Gear Oil Drain Fill Plug Seal Gaskets x 2 12-191833