Mercury Outboard Gear Housing Assembly, Complete 20" – Fits Mercury 40-60 HP Bigfoot 4-Stroke
Mercury Outboard Gear Housing Assembly, Complete 20" – Fits Mercury 40-60 HP Bigfoot 4-Stroke is backordered and will ship as soon as it is back in stock.
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Worry-free returns
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Mercury Outboard Gear Housing Assembly, Complete 20" – Fits Me...
Product Details
This is a complete aftermarket Mercury Outboard Gear Housing Assembly, Complete 20", designed as a direct-fit replacement for Mercury 40–60 HP Bigfoot 4-Stroke outboard motors (2002–2006, s/n 1C033810 & Below). It provides an integrated solution for replacing a damaged or worn lower unit, matching OEM performance and specifications.
It directly replaces Mercury part numbers 1667-9011G70 and 1667-9011G90, and is equivalent to Sterndrive Engineering (SEI) part 90-205-B20S.
- Installation Method: Direct bolt-on replacement
- Shaft Length: 20" (Long)
- Included Components: Complete assembly as pictured
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury Marine | 1667-9011G90 | Current OEM part number. |
| Mercury Marine | 1667-9011G70 | Superseded by 1667-9011G90. |
| Sterndrive Engineering | 90-205-B20S | Aftermarket cross-reference. |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Mercury | 40 EFI (4 CYL.) | 40 | 4-Stroke | 0P153500 THRU 0P400999 | 1667-9011G90 |
| Mercury | 40 EFI (4 CYL.) | 40 | 4-Stroke | 0P401000 THRU 0P515896 | 1667-9011G90 |
| Mercury | 40 EFI (4 CYL.) | 40 | 4-Stroke | 0T409000 THRU 1B344306 | 1667-9011G90 |
| Mercury | 40 EFI (4 CYL.) | 40 | 4-Stroke | 1C000001 THRU 1C050251 | 1667-9011G90 |
| Mercury | 50 EFI (4 CYL.) | 50 | 4-Stroke | 0P153500 THRU 0P400999 | 1667-9011G90 |
| Mercury | 50 EFI (4 CYL.) | 50 | 4-Stroke | 0P401000 THRU 0P515896 | 1667-9011G90 |
| Mercury | 50 EFI (4 CYL.) | 50 | 4-Stroke | 0T409000 THRU 1B344306 | 1667-9011G90 |
| Mercury | 50 EFI (4 CYL.) | 50 | 4-Stroke | 1C000001 THRU 1C050251 | 1667-9011G90 |
| Mercury | 60 EFI (4 CYL.) | 60 | 4-Stroke | 0P153500 THRU 0P400999 | 1667-9011G90 |
| Mercury | 60 EFI (4 CYL.) | 60 | 4-Stroke | 0P401000 THRU 0P515896 | 1667-9011G90 |
| Mercury | 60 EFI (4 CYL.) | 60 | 4-Stroke | 0T409000 THRU 1B344306 | 1667-9011G90 |
| Mercury | 60 EFI (4 CYL.) | 60 | 4-Stroke | 1C000001 THRU 1C050251 | 1667-9011G90 |
Technical Specs
- Product Type
- Complete Gear Housing Assembly (Lower Unit)
- Installation
- Direct Replacement
- Connection
- 20" Shaft Length
- Housing Material
- Aluminum
- Housing Color
- Black
- Product Dimensions
- 69.0 (Length) × 26.0 (Width) × 116.0 (Height)
- Weight
- 61.00 lbs (27.67 kg)
- Gear Ratio
- 2.33:1
- Torpedo Diameter
- 4.25" (107.95 mm)
- Pinion Teeth
- 12
- Warranty
- Manufacturer warranty through Mercury Marine
- Other Technical Attributes
- Long shaft (20"), gear housing for Bigfoot models
What’s in the Box
- 1 x Gear Housing Assembly, Complete (1667-9011G90)
Installation Notes
- Ensure the engine is safely tilted and secured. Disconnect the battery and spark plug leads before beginning work.
- Drain the gearcase oil completely from the old lower unit into an approved container.
- Remove the bolts securing the lower unit to the outboard's midsection and carefully detach the old assembly.
- Clean the mating surfaces on the midsection, removing any old gasket material or corrosion.
- Visually inspect the new gear housing, confirming the driveshaft splines and water tube grommet are clean and undamaged.
- Lightly grease the driveshaft splines before carefully aligning the new unit. Ensure the shift shaft and driveshaft align correctly.
- Install and tighten the mounting bolts to the manufacturer's specified torque sequence and values.
- Fill the new gearcase with the recommended marine gear lubricant until it flows from the upper vent screw, then replace both plugs.
- Reconnect the battery and test engine operation in a safe environment, checking for proper shifting and water pump function.
Troubleshooting & FAQ
How do I confirm this fits my specific engine model?
The most reliable way is to match your engine's serial number to the ranges listed in the Engine & Model Compatibility table. Part numbers can be superseded, but serial number ranges provided by the manufacturer are typically accurate.
What is a "Bigfoot" gearcase?
A "Bigfoot" gearcase is a larger, heavy-duty lower unit designed to swing a larger-diameter propeller. This provides more thrust and is common on pontoons and heavy boats. This unit has a 2.33:1 gear ratio specific to Bigfoot models.
My old part number is 1667-9011G70. Will this assembly work?
Yes. The part number 1667-9011G90 is the official superseded part from Mercury Marine, replacing the older 1667-9011G70. It is a direct replacement.
What are common signs that my gear housing is failing?
Common symptoms include a grinding or clunking noise when shifting, difficulty shifting into gear, visible metal shavings in the gear oil (a milky or creamy appearance also indicates a seal failure), or vibrations felt through the boat during operation.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and manufactured in an ISO 9001 certified facility, with batch inspections for quality and consistency.
Shipping speed & cost
We ship worldwide quickly—typical transit is 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
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