Seal – Fits Mercury/Mercruiser Outboards and Sterndrives (Replaces Mercury Marine 191833)

Product Details

This Seal – Fits Mercury/Mercruiser Outboards and Sterndrives (Replaces Mercury Marine 191833) is a crucial factory-style replacement designed for the 3/8-16 drain/fill screw. It is engineered for a precise fit on all MerCruiser sterndrives and the majority of Mercury/Mariner outboards, with the exception of models of Japanese origin. It is also commonly used in most lower units and sea water pumps, ensuring a reliable, leak-free seal in demanding marine environments.

This part provides a direct interchange for multiple OEM and aftermarket numbers, including Mercury Marine 191833, Johnson Evinrude 307552, GLM 31170, and Sierra 18-2945, among others. The current active part number from Mercury/Quicksilver that supersedes 12-191833 is 12-8M0187157.

• Installation is straightforward for DIY maintenance.
• Constructed from a durable, non-asbestos composite gasket material.
• Engineered to be corrosion-resistant for longevity in marine conditions.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Designed for all MerCruiser sterndrives and most Mercury/Mariner outboards (excluding Japanese models) that use a 3/8-16 drain/fill screw.

While specific models are listed, this part cross-references to OEM numbers 307552/0307552 and 311598/0311598, covering a wide range of applications.

Technical Specs

Product Type

Drain Screw Gasket/Seal

Installation

Easy, DIY

Connection

Used with 3/8-16 drain/fill screw

Housing Material

Non-asbestos gasket (composite)

Housing Color

Blue

Dimensions

Outer Diameter: 14 mm (0.55 in), Inner Diameter: 9 mm (0.35 in), Thickness: 1.5 mm (0.06 in)

Weight

0.176 oz (0.00 kg)

Fitting Type

Flat washer

Thread Size

3/8-16

Other Technical Attributes

Designed for marine environments, corrosion-resistant

What’s in the Box

• 1 x SEAL-BLUE (191833)

Installation Notes

1. Position a suitable drain pan underneath the gearcase drain plug.
2. Using the correct size wrench, carefully remove the gear lube drain/fill screw.
3. Inspect and remove the old gasket from the screw or gearcase. Discard the old gasket.
4. Clean the threads of the drain screw and the sealing surface on the gearcase to ensure they are free of debris.
5. Slide the new seal over the screw threads until it sits flush against the screw head.
6. Reinstall the drain screw and tighten it to the manufacturer's specified torque. Do not overtighten, as this can damage the seal or threads.
7. After filling the gearcase with the proper lubricant, check for any leaks around the drain screw.

Troubleshooting & FAQ

Safety & Important Info

• Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
• This is an aftermarket replacement, not an OEM component.
• Professional installation is recommended for safety and performance.

About Sea Sierra

• Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world durability.
• Fast Global Fulfillment — We offer free standard delivery to most regions, with parts typically arriving in 5–15 days.
• Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.