Propeller Shaft Oil Seal for Mercury, Mariner & Force Outboards – Replaces 26-70081
Propeller Shaft Oil Seal for Mercury, Mariner & Force Outboards – Replaces 26-70081 is backordered and will ship as soon as it is back in stock.
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Propeller Shaft Oil Seal for Mercury, Mariner & Force Outboards...
Propeller Shaft Oil Seal for Mercury, Mariner & Force Outboards – Replaces 26-70081 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket propeller shaft oil seal is intended for selected Mercury, Mariner, and Force outboard lower units. Installed in the gearcase, it helps retain gear oil and prevent water intrusion around the propeller shaft. Always compare the original seal, dimensions, and applicable engine information before ordering.
This seal replaces Mercury and Quicksilver part number 26-70081. Additional aftermarket reference numbers include Sierra 18-2053, GLM 85530, and UAN Marine 91255-ZW1-003.
- Designed for press-fit installation in the lower-unit gearcase.
- Nitrile rubber (NBR) sealing material.
- Helps retain gear oil and limit water entry at the propeller shaft.
- Single replacement seal; installation hardware and additional seals are not included.
Part Number Matrix
Use the following references when comparing the replacement with an existing seal or parts catalog listing.
| Brand | Part Number |
|---|---|
| Mercury | 26-70081 |
| Quicksilver | 26-70081 |
| Sierra | 18-2053 |
| GLM | 85530 |
| UAN Marine | 91255-ZW1-003 |
Engine & Model Compatibility
The applications below are reference applications associated with part number 26-70081. Fitment can vary by model, year, gearcase configuration, and serial-number range. Confirm the exact engine model and compare the original seal before installation.
| Brand | Model | Rated HP | Stroke / Configuration | Years | Reference Part No. |
|---|---|---|---|---|---|
| Mercury | 30 HP | 30 | 2-Stroke | 1979–1997 | 26-70081 |
| Mercury | 35 HP | 35 | 2-Stroke | 1984–1989 | 26-70081 |
| Mercury | 40 HP | 40 | 2-Stroke | 1978–1997 | 26-70081 |
| Mercury | 45 HP | 45 | 2-Stroke | 1986–1989 | 26-70081 |
| Mercury | 50 HP | 50 | 2-Stroke | 1978–1997 | 26-70081 |
| Mercury | 60 HP | 60 | 2-Stroke | 1979–1991 | 26-70081 |
| Mercury | 65 HP | 65 | 3-cylinder | 1979–1985 | 26-70081 |
| Mercury | 70 HP | 70 | 3-cylinder | 1979–1985 | 26-70081 |
| Mercury | 75 HP | 75 | 3-cylinder | 1978–1997 | 26-70081 |
| Mercury | 80 HP | 80 | 3-cylinder | 1978–1989 | 26-70081 |
| Mercury | 90 HP | 90 | 3-cylinder | 1978–1997 | 26-70081 |
| Mercury | 100 HP | 100 | 4-cylinder | 1978–1990 | 26-70081 |
| Mercury | 115 HP | 115 | 4-cylinder | 1978–1997 | 26-70081 |
| Mercury | 125 HP | 125 | 4-cylinder | 1978–1997 | 26-70081 |
| Force | 75–120 HP | 75–120 | 2-Stroke | 1989–1999 | 26-70081 |
Mariner applications may use the same reference part number, but exact fitment should be confirmed against the specific model and serial-number information.
| Brand | Model | Rated HP | Stroke | Years | Reference Part No. |
|---|---|---|---|---|---|
| Force | 75 | 75 | 2-Stroke | 1999 | 26-70081 |
| Force | 90 | 90 | 2-Stroke | 1995–1999 | 26-70081 |
| Force | 120 | 120 | 2-Stroke | 1995–1999 | 26-70081 |
Technical Specs
- Product Type
- Propeller shaft oil seal
- Installation Location
- Lower unit / gearcase
- Installation Type
- Press fit
- Sealing Material
- Nitrile rubber (NBR)
- Color
- Black
- Inside Diameter
- 30.2 mm (1.188 in)
- Outside Diameter
- 43 mm (1.689 in)
- Width
- 6.3 mm (0.247 in)
- Function
- Helps retain gear oil and prevent water intrusion at the propeller shaft
What’s in the Box
- 1 x Propeller shaft oil seal
Installation Notes
- Secure the lower unit on a suitable workbench and place a drain pan beneath the gearcase.
- Remove the lower drain screw and drain the gear oil. Inspect the oil for a milky appearance, which may indicate water intrusion.
- Remove the propeller assembly, including the propeller nut, thrust washer, and spacers.
- Remove the old propeller shaft seal with a suitable seal puller or carefully with a flat screwdriver. Avoid scratching or gouging the seal bore.
- Clean the seal housing and remove old sealant, corrosion, and debris.
- Apply a thin, appropriate layer of marine grease or sealant to the outer edge of the replacement seal as specified by the engine service information.
- Press the seal evenly into position using a suitable seal driver or socket that contacts the outer diameter. Do not strike the sealing lip.
- Apply marine grease to the propeller shaft and the inner lip of the new seal.
- Reinstall the propeller assembly, washers, and spacers in the correct order. Tighten the propeller nut to the engine manufacturer’s specification.
- Refill the gearcase with the recommended gear oil through the lower drain opening until oil appears at the upper vent opening, then reinstall and tighten both screws.
Follow the service manual for the exact disassembly procedure, seal orientation, sealant requirements, torque values, and gear-oil specification for your engine.
Troubleshooting & FAQ
How do I confirm fitment for my engine?
Compare your engine brand, model, horsepower, year, and serial-number range with the applicable service information. Also compare the original seal’s reference number and dimensions. The reference number alone should not be used to ignore differences in gearcase design.
What are signs of a failing propeller shaft oil seal?
Possible signs include gear oil leaking near the propeller shaft, milky or creamy gear oil caused by water contamination, or fishing line wrapped around the propeller shaft. Remove fishing line carefully and inspect the seal and shaft for damage.
How often should lower-unit seals be replaced?
There is no universal replacement interval for this seal. Inspect the gear oil regularly and replace the seal when leakage, water contamination, damage, or lower-unit service indicates that replacement is necessary.
Can I reuse the seal after removing the propeller shaft?
Reuse is not recommended. A removed oil seal may be distorted or damaged and may not seal reliably after reinstallation. Use a new seal during reassembly.
Is this an OEM part?
No. This listing is for an aftermarket replacement seal corresponding to the reference numbers shown above. It is not sold as a Mercury, Mariner, Quicksilver, Sierra, GLM, or Force branded OEM component.
Does the package include additional gaskets or installation tools?
No. The package contains one propeller shaft oil seal only. Additional gaskets, tools, gear oil, and installation hardware are not included unless specifically stated in the order details.
Safety & Important Information
- Confirm the original part number, dimensions, model, year, and serial-number requirements before ordering.
- Do not install a seal that differs in dimensions or construction from the required application.
- Use appropriate lifting, draining, and eye-protection practices when servicing a lower unit.
- Professional installation is recommended when lower-unit service procedures or torque specifications are unfamiliar.
About Sea Sierra
- Marine replacement parts selected for practical repair and maintenance applications.
- Clear reference numbers and specifications to help customers compare replacement parts.
- Support for fitment questions based on the engine information and original part details supplied by the customer.
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