Power Head Gasket Kit – Fits Yamaha 9.9-15HP 4-Stroke Outboards (Replaces 66M-W0001-01)

$99.00

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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.).

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Power Head Gasket Kit is designed for Yamaha 9.9 HP and 15 HP 4-stroke outboard motors manufactured from 2000 to the current model year. It provides the essential gaskets needed to seal the engine's power head during assembly or repairs, ensuring a reliable, leak-free fit.

It serves as a direct replacement for Yamaha OEM part 66M-W0001-01 and is cross-referenced with Sierra 18-4355 and SAIL MARINE 66M-W0001-01.

Engineered for direct-fit installation.
Specifically designed for gasoline outboard engines.
Kit contains all necessary gaskets for a power head service.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Yamaha	66M-W0001-01
Sierra	18-4355
SAIL MARINE	66M-W0001-01

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Compatible engine models include the following Yamaha outboards.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Yamaha	F9.9	9.9	4-Stroke	2000–Current	66M-W0001-01
Yamaha	F15	15	4-Stroke	2000–Current	66M-W0001-01
Yamaha	T9.9	9.9	4-Stroke	2000–Current	66M-W0001-01	High thrust model

Technical Specs

Product Type: Power Head Gasket Kit
Installation: Direct replacement
Fuel Type: Gasoline
Dimensions: 24.5" L x 20.5" W x 2.0" H

What’s in the Box

1 x Power Head Gasket Kit (Replaces 66M-W0001-01)

Installation Notes

Disconnect the battery and ensure the engine is cool.
Drain engine oil and cooling system fluids to prevent spills.
Carefully disassemble the power head components, keeping track of all hardware.
Remove the old gaskets completely. Use a plastic scraper to avoid gouging metal surfaces.
Thoroughly clean and inspect all mating surfaces. They must be free of oil, old gasket material, and debris.
Place the new gaskets into position. Do not use any sealant unless specified by the service manual.
Reassemble all components in the reverse order of disassembly.
Torque all bolts to the manufacturer's specified values in the correct sequence.
Refill engine oil and coolant.
Start the engine and check for any leaks.

Troubleshooting & FAQ

How do I confirm this kit fits my specific engine model?

This kit fits Yamaha F9.9, F15, and T9.9 (High Thrust) 4-stroke outboards from 2000 to current. The most reliable method is to match your engine's original part number to 66M-W0001-01. Please check the compatibility table and verify your engine details before ordering.

What are common signs of a failed power head gasket?

Symptoms of a blown head gasket include engine overheating, loss of power, white smoke from the exhaust (coolant burning), or milky, emulsified engine oil (water/coolant mixing with oil).

Is this a complete gasket set for the entire engine?

No, this is a power head gasket kit. It contains the specific gaskets required for servicing the engine's cylinder head and block assembly. It does not include gaskets for the lower unit, carburetor, or other peripheral components.

Are OEM and aftermarket parts interchangeable?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials and is designed to be a direct replacement. Our parts are manufactured in an ISO 9002 facility and batch-inspected for consistency and quality.

What are your shipping speed and cost?

We ship worldwide quickly—typical transit is 5–15 days for most regions. Standard shipping is free. Expedited shipping options, where available, will be displayed at checkout.

What is the warranty and return policy?

This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window for items that are unused and in their 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.

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