Complete Gasket Kit – Fits Yamaha/Mariner 40HP (Replaces 6R6-W0001-02-00, 676-W0001-01-00, 97666M)
Complete Gasket Kit – Fits Yamaha/Mariner 40HP (Replaces 6R6-W0001-02-00, 676-W0001-01-00, 97666M) 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).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Complete Gasket Kit – Fits Yamaha/Mariner 40HP (Replaces 6R6-W0001-...
Product Details
This Complete Gasket Kit fits Yamaha/Mariner 40HP 2-Stroke engines, including the Yamaha C40 (6R6) model from 1991–1998 and various 40HP Mariner models. It serves as a comprehensive solution for powerhead resealing, containing all necessary gaskets and seals for a complete overhaul.
It provides a direct replacement for Yamaha part numbers 6R6-W0001-02-00 and 676-W0001-01-00; Mariner 97666M and 27-814556M; Sierra 18-4414; Mallory PM-4414; and WSM 500-312.
- Engineered as a direct OEM-quality replacement for straightforward installation.
- Constructed from high-quality materials to meet or exceed original specifications.
- Includes the essential head gasket, crank seals, and a complete powerhead gasket set.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6R6-W0001-02-00 |
| Yamaha | 676-W0001-01-00 |
| Mariner | 97666M |
| Mariner | 27-814556M |
| Sierra | 18-4414 |
| Mallory | PM-4414 |
| WSM | 500-312 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha engines, this kit is specifically designed for the C40 (6R6) model as listed.
For Mariner engines, this kit fits various 40HP 2-stroke models that use the cross-referenced part numbers. Please verify your part number before ordering.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yamaha | C40 (6R6) | 40 | 2-Stroke | 1991–1998 | 6R6-W0001-02-00 |
Technical Specs
- Product Type
- Complete Powerhead Gasket Kit
- Installation
- Direct OEM replacement
- Fuel Type
- Gasoline
- Housing Material
- Various (gaskets and seals)
- Package Contents
- Head gasket, crank seals, and complete powerhead gasket set
- Technical Attributes
- OEM-quality materials
- Product Dimensions
- 25.0" L x 25.5" W x 2.0" H
What’s in the Box
This kit contains a complete powerhead gasket set, which includes the following key components:
- 1 x Head Gasket
- 2 x Crank Seals
- Complete set of various powerhead gaskets and seals for a full rebuild
Installation Notes
- Disconnect the battery and fuel lines to ensure safety. Drain all engine fluids, such as coolant and oil.
- Carefully disassemble the powerhead components, taking photos or labeling parts to aid in reassembly.
- Remove all old gasket material from the mating surfaces. Use a plastic scraper and an appropriate solvent to avoid scratching the metal.
- Ensure all surfaces are perfectly clean, dry, and free of oil, grease, or old gasket residue before installing the new gaskets.
- Place the new gaskets into position. Do not use any sealant unless explicitly specified by the engine's service manual for your model.
- Reassemble the powerhead components, tightening bolts in the sequence and to the torque specifications recommended by the manufacturer.
- Reconnect fuel lines and the battery. Refill engine fluids.
- Start the engine and let it warm up, checking carefully for any fuel, oil, or coolant leaks.
Troubleshooting & FAQ
How do I confirm this gasket kit fits my engine?
The best method is to cross-reference your engine's original part number with the ones listed in our Part Number Matrix. Additionally, check the compatibility table to ensure your model and year range are included.
Are any special tools required for installation?
Standard marine mechanic tools are required. A torque wrench is essential for tightening bolts to the manufacturer's specifications to ensure a proper seal and prevent damage.
What is the difference between this kit and the original Yamaha/Mariner parts?
This is an aftermarket kit designed to meet or exceed OEM specifications. It provides a cost-effective alternative to OEM parts without compromising on quality or performance, offering comparable fit, form, and function.
Do powerhead gaskets require periodic replacement?
Gaskets are typically replaced only when the engine is being rebuilt or when there are signs of failure, such as leaks or loss of compression. They are not a routine maintenance item.
What are the signs of a failing powerhead gasket?
Common symptoms include external oil or water leaks, milky-looking oil (indicating water contamination), engine overheating, loss of power, or low compression in one or more cylinders.
Does this kit include all necessary gaskets for a powerhead rebuild?
Yes, this is a complete powerhead gasket kit. It includes all the necessary gaskets and seals required to reseal the entire engine powerhead assembly.
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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