Mercury Mariner Lower Unit Gearcase Seal Kit, 30–125 HP 2- and 4-Stroke, 3- and 4-Cylinder
Mercury Mariner Lower Unit Gearcase Seal Kit, 30–125 HP 2- and 4-Stroke, 3- and 4-Cylinder is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Mercury Mariner Lower Unit Gearcase Seal Kit, 30–125 HP 2- and 4-St...
Mercury Mariner Lower Unit Gearcase Seal Kit, 30–125 HP 2- and 4-Stroke, 3- and 4-Cylinder is backordered and will ship as soon as it is back in stock.
Product Details
This lower unit gearcase seal kit is intended for Mercury and Mariner outboards rated from 30 to 125 HP with either 2-stroke or 4-stroke powerheads and 3- or 4-cylinder configurations. It is designed for lower unit and gearcase service where worn or damaged seals, gaskets, O-rings, and related sealing components need to be replaced.
The kit is listed as an aftermarket replacement for the Mercury reference numbers 26-43035A1, 26-43035A2, 26-43035A3, 26-43035A4, and 26-43035A05. Confirm the complete engine model and serial-number range before ordering because lower-unit components can vary by gearcase design, gear ratio, and serial break.
- Lower unit and gearcase seal kit for Mercury and Mariner outboards.
- Applications covering 30–125 HP, 2-stroke and 4-stroke, 3- and 4-cylinder configurations.
- Supports gearcase resealing during lower-unit repair or maintenance.
- Aftermarket replacement; not manufactured or branded by Mercury Marine.
Part Number Matrix
These references are provided for identification and cross-reference purposes. They do not replace verification against the exact engine model and serial number.
| Brand or Reference | Part Number | Reference Type |
|---|---|---|
| Mercury | 26-43035A1 | Manufacturer reference |
| Mercury | 26-43035A2 | Manufacturer reference |
| Mercury | 26-43035A3 | Manufacturer reference |
| Mercury | 26-43035A4 | Manufacturer reference |
| Mercury | 26-43035A05 | Manufacturer reference |
| Sierra | 18-2626 | Aftermarket cross-reference |
| GLM | 87590 | Aftermarket cross-reference |
| Mallory | 9-74200 | Aftermarket cross-reference |
Engine and Model Compatibility
The company fitment range for this product is Mercury and Mariner outboards rated 30–125 HP, covering both 2-stroke and 4-stroke engines with 3- or 4-cylinder configurations.
Catalog occurrences for the referenced gearcase seal application include selected Mercury 30 HP and 40 HP models, 4-stroke applications, Bigfoot gearcases, and gear housings with different serial-number breaks. These examples are not a complete fitment list. Always compare the engine model, horsepower, stroke, cylinder count, gearcase configuration, and serial number with the applicable service or parts catalog.
| Brand | Rated HP | Stroke | Cylinder Configuration | Fitment Conditions |
|---|---|---|---|---|
| Mercury / Mariner | 30–125 HP | 2-stroke or 4-stroke | 3- or 4-cylinder | Verify exact model, gearcase design, and serial-number range before purchase. |
Important: The horsepower range alone does not confirm fitment. Do not use this listing for a specific engine unless the applicable serial-number and gearcase conditions match.
Technical Specifications
- Product Type
- Lower unit and gearcase seal kit
- Compatible Brands
- Mercury and Mariner
- Rated Horsepower Range
- 30–125 HP
- Engine Stroke
- 2-stroke and 4-stroke applications
- Cylinder Configuration
- 3- and 4-cylinder applications
- Replacement Type
- Aftermarket replacement
What’s in the Box
- One lower unit and gearcase seal kit.
Individual seal, gasket, O-ring, and washer quantities can vary by application and kit configuration. Compare the kit contents with the parts diagram for your exact engine before installation.
Installation Notes
- Obtain the correct service manual for the exact outboard model and serial-number range.
- Disconnect the battery and place the engine in neutral before beginning work.
- Drain the gearcase lubricant through the designated drain and vent openings and inspect it for water contamination or metal debris.
- Remove the propeller and lower unit according to the manufacturer’s service procedure.
- Disassemble the gearcase only as necessary to access the seals and gaskets being replaced.
- Clean mating surfaces and seal bores thoroughly. Do not damage machined surfaces during seal removal.
- Install each replacement seal, gasket, O-ring, and washer in the correct location and orientation. Use the lubricant or sealant specified by the service manual.
- Reassemble the gearcase and reinstall the lower unit using the manufacturer’s torque specifications.
- Refill the gearcase with the recommended marine gear lubricant using the correct fill procedure.
- Pressure- or vacuum-test the gearcase when the service procedure requires it, then check for leaks before returning the engine to service.
Troubleshooting and FAQ
How do I confirm this seal kit fits my outboard?
Confirm that your engine is a Mercury or Mariner model in the 30–125 HP range with a 2-stroke or 4-stroke, 3- or 4-cylinder configuration. Then verify the exact model, gearcase design, and serial-number range against the applicable parts diagram. The reference numbers alone should not be used as the only fitment check.
What are common signs of lower-unit seal failure?
Possible signs include milky or cloudy gear lubricant, water in the gearcase, lubricant leaking near the propeller shaft or driveshaft, or lubricant loss during operation. Inspect the gearcase before replacing parts because damage to shafts, bearing carriers, or sealing surfaces can also cause leaks.
Can this kit be used for every Mercury or Mariner engine from 30 to 125 HP?
No. The stated horsepower range is a broad application range, not a guarantee for every model. Serial-number breaks, gearcase design, gear ratio, stroke, cylinder configuration, and regional model differences may affect fitment.
Is this an OEM Mercury component?
No. This is an aftermarket replacement seal kit that references the listed Mercury manufacturer part numbers for identification and application matching.
Are special tools required?
Depending on the gearcase, installation may require seal drivers, bearing or carrier removal tools, a torque wrench, and a pressure/vacuum tester. Use the service manual for the exact engine and gearcase before starting work.
What lubricant should be used after installation?
Use the marine gear lubricant specified for your exact outboard by the engine manufacturer. Follow the service manual for lubricant grade, fill quantity, and filling sequence.
Safety and Important Information
- Verify the full engine model, stroke, cylinder configuration, gearcase type, and serial number before ordering.
- Do not rely on horsepower or a single reference number to confirm fitment.
- Compare the original components and applicable parts diagram before disassembly.
- Follow the manufacturer’s service procedures, torque specifications, sealant requirements, and lubricant specifications.
- Professional installation is recommended for gearcase disassembly, sealing, and pressure testing.
About Sea Sierra
- Marine replacement parts selected for practical repair and maintenance applications.
- Clear cross-reference information to help identify the correct replacement component.
- Support focused on accurate application matching and dependable service-part sourcing.
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