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Outboard Motor Parts | OEM & Aftermarket
Shop OEM and aftermarket outboard motor parts for Mercury, Yamaha, Suzuki, Honda, Johnson / Evinrude / E-TEC, Tohatsu / Nissan, and Chrysler / Force engines. Pro Marine USA carries parts for routine maintenance, troubleshooting, repair, and complete marine engine rebuilds.
Browse by outboard manufacturer or engine system, or use our OEM parts lookup to identify the correct part number before ordering. Find cooling, fuel, ignition, electrical, internal engine, lower unit, steering, trim, service kit, gasket, seal, and rebuild parts in one place.
Shop Outboard Parts by Manufacturer
Chrysler / Force Outboard Parts for Chrysler and Force outboard repair 
Honda Outboard Honda cooling, fuel, electrical, and engine parts 
Johnson / Evinrude / E-TEC Outboard Johnson, Evinrude, E-TEC, and OMC replacement parts 
Mercury Outboard Mercury and Mariner maintenance, repair, and rebuild parts 
Suzuki Outboard Suzuki service, lower unit, fuel, and engine parts 
Tohatsu / Nissan Outboard Tohatsu and Nissan outboard replacement parts 
Yamaha Outboard Yamaha maintenance, repair, lower unit, and rebuild parts Find the Correct Outboard Part
Not sure which part fits your engine? Start with the engine manufacturer, horsepower, model number, serial number, and year whenever available.
Our OEM parts lookup lets you view factory parts diagrams and identify the original part number for many popular outboard engines. Once you have the OEM number, search Pro Marine to find available OEM and aftermarket replacement options.
Use Our OEM Parts Lookup »Shop Outboard Parts by Engine System
Outboard engines use several interconnected systems. Select your manufacturer above to browse the exact categories available for your engine, including the following common repair and maintenance areas.
Common Outboard Problems and Where to Start
- Engine overheating: inspect the water pump, impeller, thermostat, pressure-control components, cooling passages, and engine anodes.
- Hard starting or rough idle: check fuel delivery, carburetor or injector operation, spark plugs, ignition components, filters, and intake sealing.
- Weak spark or no spark: test ignition coils, stators, switch boxes or ignition modules, sensors, wiring, grounds, and related electrical components.
- Low compression or poor power: inspect pistons, rings, cylinder condition, head and powerhead gaskets, bearings, and other internal engine components.
- Milky gear lube: inspect prop shaft, driveshaft, shift shaft, bearing carrier, and other lower unit seals for water intrusion.
- Lower unit or gearcase noise: inspect bearings, gears, clutch components, shafts, and gear lube condition before continued operation.
- Trim or steering problems: inspect hydraulic fluid level, seals, hoses, trim motors, pumps, steering cylinders, and mechanical connections.
Why Buy Outboard Parts from Pro Marine USA?
- OEM and aftermarket replacement options for major outboard engine brands.
- Marine engine parts for routine maintenance, professional repair, and complete rebuild projects.
- OEM diagram and part-number lookup tools to help identify the correct component before ordering.
- Dealer pricing available for qualified marine repair businesses and dealers.
- Large selection of service kits, engine parts, lower unit components, fuel system parts, electrical parts, steering, and rigging products.
- Same-day weekday shipping available on qualifying in-stock orders placed before the shipping cutoff.
OEM and Aftermarket Outboard Parts
OEM parts are supplied by the original engine manufacturer and are designed for the specific engine application. Aftermarket parts are replacement components produced by independent marine parts manufacturers and may provide additional availability or value for many common repairs.
Pro Marine carries both genuine OEM parts and quality aftermarket replacement parts for many outboard maintenance, repair, and rebuild applications. Always confirm fitment using the engine model, serial number, horsepower, year range, or OEM part number when available.
Frequently Asked Questions
How do I find the correct parts for my outboard motor?
Start by identifying the engine manufacturer, horsepower, model number, serial number, and year. Select the manufacturer above to browse by engine system, or use the OEM parts lookup to locate the original part number from a factory diagram.
Can I search Pro Marine by OEM part number?
Yes. If you already have the OEM part number, enter it into the Pro Marine site search to locate available OEM and aftermarket replacement options. If you do not know the part number, use the OEM parts lookup first.
What information should I have before ordering an outboard part?
Have the engine manufacturer, horsepower, model number, serial number, and year whenever possible. An OEM part number from the original component or parts diagram is especially helpful because visually similar parts may fit different engine families.
What is the difference between OEM and aftermarket outboard parts?
OEM parts come from the original engine manufacturer. Aftermarket parts are replacement components manufactured by other marine parts companies for compatible applications. Pro Marine carries both OEM and aftermarket options across many common outboard engine systems.
Are aftermarket outboard motor parts reliable?
Quality aftermarket marine parts are commonly used for maintenance, professional repair, and engine rebuilding. The best option depends on the application, manufacturer, availability, and customer preference.
Do you carry parts for older outboard motors?
Yes. Pro Marine carries parts for many older Mercury, Mariner, Johnson, Evinrude, Chrysler, Force, Yamaha, Honda, Suzuki, Nissan, and Tohatsu outboards. Availability varies by engine family and component.
What outboard parts are commonly replaced during routine maintenance?
Common maintenance items include engine oil, oil filters, fuel filters, spark plugs, water pump impellers, complete water pump kits, thermostats, gear lube, drain plug seals, anodes, and manufacturer-specific service kit components.
Fitment Tip: Outboard parts can vary by model, serial range, horsepower, and production year. Confirm the OEM part number or engine identification information whenever possible before ordering.
21020
37428A1
508708
55419A1
775499
77631A2
9-76134
812966A3
812966A7
812966A9
9-43330
6AW-43880-01-00
6AW-43880-02-00
18-3063
47-81242M
47-95611M
662-44352-01-00
81242M
9-45608
95611M
17461-96300
17461-96301
17461-96302
17461-96310
17461-96311
17461-96312
18-3096
5031417
778296
9-45219
64E-43866-09-00
Fits Select Mercury 25-70HP Gearcase Applications
Designed for Mercury and Mariner lower unit bearing carrier assemblies. The Mercury 21700 Bearing, also listed as 31-21700, is a needle / roller bearing used in the gearcase bearing carrier area to support the propeller shaft.
Compatibility
This bearing is used across many Mercury and Mariner small to midrange outboard gearcases. OEM where-used data shows applications across multiple 25-70HP gearcase families, including 2-stroke, 4-stroke, BigFoot, and Jet models.
Application Chart
| Brand | Engine Family | Horsepower | System | Component |
|---|---|---|---|---|
| Mercury / Mariner | Small 4-Stroke Outboards | 25-30 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | 2-Cyl / 3-Cyl Outboards | 35-40 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | 3-Cyl / 4-Cyl Outboards | 45-60 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | BigFoot / 4-Stroke Models | 40-60 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | 70HP 3-Cyl Outboards | 70 HP | Gearcase / Lower Unit | Bearing Carrier / Prop Shaft Bearing |
| Mercury / Mariner | Jet Models | 30-45 Jet | Gearcase / Jet Drive | Bearing Carrier / Prop Shaft Bearing |
Always confirm compatibility using your engine serial number, gearcase type, and existing part number before ordering.
Part Numbers & Cross References
| Reference Type | Part Number |
|---|---|
| Mercury OEM Part | 21700 |
| Mercury OEM Part | 31-21700 |
| Cross Reference # | 18-1095 |
| Cross Reference # | 93-263-12 |
| Cross Reference # | 11428 |
What This Part Is Used For
This bearing is used in the lower unit bearing carrier to support the propeller shaft. A properly functioning bearing helps maintain smooth prop shaft rotation and proper gearcase operation.
Bearings are commonly inspected or replaced during lower unit rebuilds, bearing carrier service, prop shaft repair, or when gearcase noise, vibration, or wear is found.
Frequently Asked Questions
What does Mercury 21700 fit?
This bearing fits select Mercury and Mariner small to midrange gearcases, commonly in the 25-70HP range. Always verify by serial number and gearcase diagram.
Where is this bearing used?
It is used in the lower unit bearing carrier area to support the propeller shaft.
Is 21700 the same as 31-21700?
Yes. Mercury commonly lists this bearing as 31-21700.
When should this bearing be replaced?
Replace it during lower unit rebuilds or when wear, noise, corrosion, or prop shaft bearing damage is found.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer or technician? We offer dealer pricing for qualified businesses.
Shipping Policy
- Free shipping on orders over $100 (continental U.S.)
- Ships via UPS, USPS, and FedEx
- 5:30 PM EST daily cutoff
- Typical delivery 1–5 business days
30-Day Return Policy
- Returns within 30 days
- Items must be unused and in original packaging
- Return authorization is required before sending items back
Contact Us
Phone: 941-721-3000
Searchable Part Numbers
Part Number: 21700
Cross Reference #: 31-21700, 18-1095, 93-263-12, 11428
Common Search Terms: Mercury 21700 bearing, Mercury 31-21700 bearing, Mercury bearing carrier bearing, Mercury prop shaft bearing
6KW-43880-01-00
6KW-43880-02-00
63P-43880-10-00
63P-43880-11-00
63P-43880-21-00
63P-43880-22-00
18-3246
19210-ZV4-013
19210-ZV4-651
19210-ZV4-651
9-45101
64E-43867-09-00
67F-81960-10-00
67F-81960-11-00
67F-81960-12-00
804278A12
804278T
804278T1
804278T11