PRODUCT DETAILS
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
SHIPPING & DELIVERY
Delivery & Returns Policy
Delivery
Standard Delivery
- £6: Royal Mail Tracked 24 Service
- £3.99: Large Letter - Royal Mail 1st Class Post (Untracked)
We offer free delivery on all orders over £150 (excludes outboard engines).
Orders placed before 1:00 PM (Monday-Friday) are usually dispatched the same working day.
Most parcels are delivered within 24 hours, but please allow extra time for courier delays that may occur outside our control.
For outboard engines, please contact us for a delivery quote.
Important: Please ensure your shipping address is correct before completing checkout. SSI Marine is not responsible for parcels sent to an incorrect address provided by the buyer.
Tracking Your Order
Once your order has been dispatched, you will receive a tracking number via email (after 5 PM on the day of dispatch).
Tracking is available only for parcels sent via Royal Mail Tracked 24.
Large Letter orders are sent via Royal Mail 1st Class Post (untracked).
Returns
We accept returns of unused and undamaged items within 30 days of purchase.
Returned items must be in sellable condition and include the original packaging.
Please do not tape, label, or write directly on the product's original box.
Important: Do not return items in their original product boxes only, they must be placed inside a protective outer box or bag. Parcels returned like the example below will be subject to a 20% restocking fee.
Return shipping costs are the customer's responsibility.
Please include your order details and reason for return inside the parcel.
Refunds
Refunds are issued for the item purchase price only (shipping costs are non-refundable).
All refunds will be made using the same payment method as your original order.
Items returned in poor condition or without proper packaging may incur a 20% restocking fee.
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