GASKET – Fits Mercury Marine Merc 200, 20 HP Outboards (Replaces 27-39626)
GASKET – Fits Mercury Marine Merc 200, 20 HP Outboards (Replaces 27-39626) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
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Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
GASKET – Fits Mercury Marine Merc 200, 20 HP Outboards (Replaces 27...
Product Details
This replacement GASKET – Fits Mercury Marine Merc 200, 20 HP Outboards (Replaces 27-39626) is designed for specific Mercury Marine 2-stroke, 20 HP outboard models manufactured between 1978 and 1980. It ensures a precise seal between the water pump base and the gear housing, which is critical for preventing cooling system leaks.
This part serves as a direct interchange for Mercury Quicksilver part number 27-39626 and Sierra aftermarket part number 18-2829.
- Installs between the water pump base and gear housing assembly.
- This listing is for a new old stock item; external packaging may show wear or vary from photos.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket suppliers.
| Brand | Part Number | Notes |
|---|---|---|
| Mercury Quicksilver | 27-39626 | OEM Reference |
| Sierra | 18-2829 | Aftermarket Interchange |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Mercury Marine owners, this part is used in the Gear Housing Assembly for specific Merc 200 models from the late 1970s. Verify your model and serial number range for an exact match.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Mercury Marine | Merc 200 (Model 20) | 20 | 2-Stroke | 1978–1980 | 27-39626 | Water pump base to gear housing gasket |
| Mercury Marine | Merc 200 | 20 | 2-Stroke | 2827677–3226957 | 27-39626 | Used in Gear Housing Assembly |
Technical Specs
- Product Type
- Gasket
- Installation Location
- Water Pump Base to Gear Housing
- Product Dimensions
- 11.0" L x 10.5" W x 0.1" H
- Product Weight
- 0.14 kg (5 ounces)
- Other Attributes
- New Old Stock; Packaging May Vary
What’s in the Box
- 1 x GASKET (27-39626)
Installation Notes
- Ensure the engine is off, cool, and the battery is disconnected before starting.
- Remove the lower unit (gearcase) from the outboard's driveshaft housing.
- Unbolt and carefully lift the water pump housing away from the gearcase to expose the base.
- Remove the old gasket. Scrape away any remaining gasket material or sealant from both mating surfaces until they are perfectly clean and smooth.
- Place the new gasket into position on the gear housing, aligning it with the bolt holes and water passages.
- Reinstall the water pump assembly over the new gasket and tighten the bolts to the manufacturer's specified torque.
- Reattach the lower unit to the engine, ensuring the driveshaft, shift shaft, and water tube are correctly aligned.
Troubleshooting & FAQ
How do I know if this gasket will fit my Merc 200 engine?
This gasket is specifically for 20 HP Mercury "Merc 200" models from 1978–1980. Cross-reference your engine's model, year, or serial number (if it falls within 2827677–3226957) with the compatibility table. When in doubt, compare our product images to your old part before ordering.
What are the signs of a failing water pump base gasket?
Common symptoms include the engine overheating at idle or low speeds, a weak water stream from the tell-tale outlet, or visible water leaks around the lower unit's seams. These indicate a loss of water pressure in the cooling system, which this gasket helps to seal.
How often should this gasket be replaced?
It is best practice to replace the water pump gaskets, including this one, every time you service the water pump impeller. This is typically recommended every 1-2 years or 100-200 hours of use, depending on operating conditions (especially in saltwater).
Is this gasket made of the same material as the original Mercury part?
This aftermarket gasket is designed to meet or exceed OEM specifications. It is made from high-quality, marine-grade composite materials chosen for their durability and sealing properties in a water pump environment, ensuring performance comparable to the original.
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
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