677-11181-A0 Cylinder Head Gasket for Yamaha Mariner 6HP 8HP 6B 8B | JLM Marine

Cylinder Head Gasket – Fits Yamaha Mariner 6HP 8HP 6B 8B 2-Stroke Outboards

This aftermarket Cylinder Head Gasket is engineered for Yamaha and Mariner 6 HP and 8 HP 2-stroke outboard engines, including models 6B and 8B with serial numbers starting with 677. Designed to deliver reliable sealing performance, this gasket ensures proper compression and prevents coolant or combustion leaks in your outboard motor.

Direct replacement for Yamaha OEM part numbers 677-11181-A0-00, 677-11181-A1-00, 677-11181-01-00, and 677-11181-00-00, offering a cost-effective solution without compromising on quality or fitment.

• Precision-cut for accurate fitment on 6HP and 8HP 2-stroke models
• Manufactured to OEM specifications for consistent sealing performance
• Suitable for routine maintenance and cylinder head reassembly

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket sources.

Compatible Engine Models

Confirm your engine model/year in the table below. For Yamaha owners, here's a guide to help you identify your engine's serial/model: Yamaha Serial Number Guide. You can also review exploded diagrams to verify part numbers: Yamaha Parts Diagrams & Catalog.

Technical Specifications

Package Contents

Your purchase includes:

• 1 × Outboard Cylinder Head Gasket

Installation Guide

1. Disconnect the spark plug wire to prevent accidental engine start during service.
2. Remove the engine cowling and locate the cylinder head assembly.
3. Unbolt and carefully lift the cylinder head from the engine block. Take care not to damage the mating surfaces.
4. Remove the old gasket and thoroughly clean both the cylinder head and block surfaces with a gasket scraper and solvent to remove all residue.
5. Inspect the mating surfaces for warping, cracks, or damage. Resurface or replace components if necessary.
6. Position the new cylinder head gasket onto the engine block, aligning all bolt holes and coolant passages carefully.
7. Place the cylinder head back onto the gasket, ensuring proper alignment with dowel pins if present.
8. Install head bolts finger-tight in a crisscross pattern starting from the center outward.
9. Torque the head bolts to manufacturer specifications in multiple stages using a torque wrench, following the recommended sequence.
10. Reconnect all coolant hoses, fuel lines, and electrical connections that were removed during disassembly.
11. Reinstall the engine cowling and reconnect the spark plug wire.
12. Start the engine and check for leaks around the cylinder head gasket area. Allow the engine to reach operating temperature and inspect again.

Troubleshooting & FAQ

Q: How do I confirm this gasket fits my Yamaha or Mariner engine?
A: Verify your engine model is 6HP or 8HP 2-stroke (6B or 8B) with a serial number beginning with 677. Cross-reference the OEM part numbers listed above with your engine's parts diagram or service manual.

Q: What are the signs that my cylinder head gasket needs replacement?
A: Common symptoms include coolant leaks around the cylinder head, overheating, loss of compression, rough idling, white smoke from the exhaust, or coolant mixing with engine oil.

Q: How often should I replace the cylinder head gasket?
A: Replace the gasket whenever the cylinder head is removed for service, such as during top-end rebuilds, valve work, or if you notice compression or coolant leaks. There is no set interval—replacement is condition-based.

Q: Should I use sealant with this gasket?
A: Follow your engine manufacturer's specifications. Most modern composite gaskets are designed to seal without additional sealant. Applying sealant when not required can cause improper sealing or gasket failure.

Q: Can I reuse the old cylinder head gasket?
A: No. Cylinder head gaskets are designed for one-time use and compress permanently during installation. Reusing a gasket will result in poor sealing and potential engine damage.

Q: Is this an OEM or aftermarket part?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.