Gearcase Seal Kit – Fits Mercury/Mariner 150 HP EFI FourStroke (Replaces 8M0057716)
Gearcase Seal Kit – Fits Mercury/Mariner 150 HP EFI FourStroke (Replaces 8M0057716) is backordered and will ship as soon as it is back in stock.
Worry-free returns
Worry-free returns
Shop with confidence. If you’re not completely satisfied, eligible items may be returned within the return window, provided they are unused and in original packaging.
If the return is due to our error or a defective item, we’ll make it right.
Please contact us before returning any item.
Delivery and Shipping
Delivery and Shipping
Orders are typically processed within 1–2 business days.
U.S. orders usually arrive within 6–15 days, depending on stock location and destination.
International delivery times may vary due to customs processing.
Tracking information will be provided once your order ships.
Gearcase Seal Kit – Fits Mercury/Mariner 150 HP EFI FourStroke (Rep...
Gearcase Seal Kit – Fits Mercury/Mariner 150 HP EFI FourStroke (Replaces 8M0057716) is backordered and will ship as soon as it is back in stock.
Product Details
This Gearcase Seal Kit – Fits Mercury/Mariner 150 HP EFI FourStroke Outboards (Replaces 8M0057716) contains the necessary components to service the lower unit on Mercury/Mariner 150 HP EFI FourStroke outboard engines from 2007 and newer (serial number 1B905505 and up). It provides a complete solution for replacing worn or damaged seals to prevent water intrusion and oil leaks.
This kit is a direct replacement for Mercury part number 8M0057716 and GLM Marine 87527.
- Includes all necessary gaskets and seals for a complete gearcase service.
- Engineered with high-quality, corrosion-resistant materials for durability in marine environments.
- Establishes a watertight seal to protect internal gearcase components from water intrusion.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Mercury | 8M0057716 |
| GLM Marine | 87527 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury and Mariner owners, please verify your engine's model, horsepower, and serial number range to ensure correct fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Mercury/Mariner | FourStroke | 150 | 4-Stroke | 2007 and up (SN 1B905505 & up) | 8M0057716 |
| Mercury | Sea Pro | 150 | 4-Stroke | (SN 2B139139 & up) | 8M0057716 |
| Mercury/Mariner | EFI | 135 | 4-Stroke | (SN 2B131942 & up) | 8M0057716 |
| Mercury | 7150F23ZD, 7150F24ZD, 7150F13ZD | 150 | 4-Stroke | 2011 | 8M0057716 |
Technical Specs
- Product Type
- Gearcase Seal Kit
- Installation
- Gaskets and seals for gearcase/lower unit
- Housing Material
- High-quality, corrosion-resistant materials
- Weight
- 0.29 lb (0.13 kg)
- Other Technical Attributes
- Watertight seal for protection against water intrusion
What’s in the Box
This kit includes all components listed below. Note that quantities were not available at the time of publication.
- SEAL (Replaces OEM 830749)
- SEAL, Oil (Replaces OEM 89238)
- O-RING, (2.175 x .103) (Replaces OEM 896523)
- O-RING, (.987 x .103) (Replaces OEM 45258)
- O-RING, (.796 x .139) (Replaces OEM 21836)
- SEAL, Oil (Replaces OEM 816464 1)
Installation Notes
- Position the outboard securely and place a drain pan under the lower unit. Remove the gear lube drain and vent screws to drain the gearcase oil completely.
- Remove the propeller and mounting hardware. Disconnect the speedometer tube if equipped.
- Unbolt and carefully remove the gearcase (lower unit) from the outboard's driveshaft housing.
- Disassemble the gearcase components, including the bearing carrier and driveshaft, taking care to note the order and orientation of parts.
- Carefully remove all old seals, O-rings, and gaskets from their respective locations. Thoroughly clean all sealing surfaces.
- Install the new seals and O-rings from the kit, applying a light coat of marine grease to help with installation and sealing.
- Reassemble the gearcase components in reverse order, ensuring all parts are correctly seated and torqued to manufacturer specifications.
- Reinstall the lower unit onto the outboard, ensuring the driveshaft, water tube, and shift shaft are properly aligned.
- Refill the gearcase with the manufacturer-recommended gear lube until it flows from the upper vent hole, then reinstall and tighten both screws.
Troubleshooting & FAQ
How do I know if my gearcase seals are failing?
Common signs of failing gearcase seals include a milky, white, or creamy appearance in the gear lube (indicating water intrusion) or visible oil leaks around the propeller shaft or lower unit housing. A pressure and vacuum test can also confirm a leak.
Will this kit fit Mercury models other than the 150 HP FourStroke?
Yes, this kit is also listed as compatible with select 135 HP FourStroke EFI models (serial number 2B131942 and up) and 150 HP Sea Pro models (serial number 2B139139 and up). Always verify your engine's serial number against the compatibility table.
How often should I replace my gearcase seals?
There is no fixed replacement interval, but it is best practice to inspect the gear lube color during every annual service or 100-hour interval. Seals should be replaced immediately if water intrusion is found or if the lower unit is disassembled for other service.
Is this kit a complete rebuild kit?
This is a seal kit, designed to address leaks and routine service. It contains gaskets, seals, and O-rings but does not typically include bearings, gears, or other hard parts. Please review the 'What’s in the Box' section for a list of included components.
What is the main difference between this aftermarket kit and an OEM kit?
Our aftermarket kits are designed to meet or exceed OEM specifications for fit, function, and material quality at a more competitive price point. While the parts are not branded by the original engine manufacturer, they are produced in an ISO 9002 certified facility and undergo rigorous quality control.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
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 tested for real-world conditions.
- Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
- Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.
Payment & Security
Payment methods
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
