Head Gasket – Fits Mercury/Mariner 35-60 HP 4-Stroke Outboard Motors (Replaces 27-857081, 27-8M0045278)

$44.79 $71.00

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Head Gasket – Fits Mercury/Mariner 35-60 HP 4-Stroke Outboard Motors (Replaces 27-857081, 27-8M0045278) is backordered and will ship as soon as it is back in stock.

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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 replacement Head Gasket is designed for Mercury and Mariner 35-60 HP 4-stroke outboard motors, specifically models with serial numbers 1C453840 and higher. It ensures a precise seal for 4-cylinder engine configurations, restoring performance and preventing leaks.

It serves as a direct interchange for Mercury/Quicksilver part numbers 27-857081, 27-8M0045278, and 8M0118179.

Installation: Engineered for direct OEM replacement fit.
Engine Type: Compatible with 4-cylinder gasoline engines.
Package Includes: One head gasket for a complete service.

Part Number Matrix

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

Brand	Part Number	Superseded By
Mercury / Quicksilver	27-857081	27-8M0045278
Mercury / Quicksilver	27-8M0045278	8M0118179
Mercury / Quicksilver	8M0118179

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This gasket is designed for specific Mercury and Mariner 4-stroke models with serial numbers 1C453840 and higher.

Brand	Model	Rated HP	Stroke	OEM Part No.	Notes
Mercury	35 HP JET	35	4-Stroke	27-857081, 27-8M0045278	Serial number 1C453840 & up
Mercury	40 HP EFI	40	4-Stroke	27-857081, 27-8M0045278	Serial number 1C453840 & up
Mercury	40 HP EFI Sea Pro	40	4-Stroke	27-857081, 27-8M0045278	Serial number 1C453840 & up
Mercury	50 HP EFI	50	4-Stroke	27-857081, 27-8M0045278	Serial number 1C453840 & up
Mercury	60 HP EFI	60	4-Stroke	27-857081, 27-8M0045278	Serial number 1C453840 & up
Mercury	60 HP Sea Pro	60	4-Stroke	27-857081, 27-8M0045278	Serial number 1C453840 & up

Technical Specs

Product Type: Cylinder Head Gasket
Installation: Direct OEM replacement
Fuel Type: Gasoline
Engine Configuration: For 4-cylinder engines
Dimensions: 36.5 cm L x 15.5 cm W x 0.5 cm H
Weight: 49.9 g (1.76 oz)

What’s in the Box

1 x Head Gasket (Replaces 27-857081 / 27-8M0045278 / 8M0118179)

Installation Notes

Disconnect the battery and relieve any pressure from the fuel system before starting.
Drain the engine coolant and oil completely.
Remove the valve cover, intake/exhaust manifolds, and any other components blocking access to the cylinder head.
Loosen and remove the cylinder head bolts in the reverse sequence specified by the manufacturer's service manual.
Carefully lift the cylinder head from the engine block. Avoid using pry tools that could damage mating surfaces.
Remove the old head gasket. Thoroughly clean both the cylinder head and engine block surfaces of all old gasket material and residue.
Position the new head gasket correctly on the engine block, ensuring it aligns with all dowels and passages.
Carefully lower the cylinder head back into place.
Install new or inspected head bolts. Torque them in the correct sequence and to the precise values found in your engine’s official service manual.
Reassemble all previously removed components in reverse order.
Refill the engine with fresh coolant and oil to the specified levels.
Reconnect the battery, start the engine, and meticulously check for any fuel, oil, or coolant leaks.

Troubleshooting & FAQ

How do I know if this head gasket fits my engine?

This gasket is for Mercury/Mariner 35-60 HP 4-stroke outboard motors with serial numbers 1C453840 and higher. Always cross-reference your engine's part number with the ones listed (27-857081, 27-8M0045278, 8M0118179) and verify the engine model in our compatibility table.

What are the common signs of a failed head gasket?

Symptoms of a blown head gasket include engine overheating, loss of power, white smoke from the exhaust (coolant burning), milky or foamy engine oil (coolant mixing with oil), or external coolant/oil leaks from the seam between the cylinder head and engine block.

Is this gasket made from the same material as the OEM part?

Our aftermarket gaskets are engineered using high-quality materials designed to meet or exceed OEM specifications for durability and sealing performance under marine conditions. While the exact composition may differ, it provides a comparable seal.

Do I need to use a sealant with this gasket?

Most modern head gaskets, including this one, are designed to be installed dry without any additional sealants. Applying sealant can interfere with the gasket's ability to create a proper seal. Always follow the instructions in your engine's service manual.

Can I reuse my old cylinder head bolts?

It is strongly recommended to use new cylinder head bolts. Many are "torque-to-yield" (TTY) bolts that stretch permanently during the initial installation and cannot provide the correct clamping force if reused, leading to premature gasket failure.

How often should a head gasket be replaced?

A head gasket is not a routine maintenance item. It is designed to last the life of the engine and should only be replaced when it fails. Its lifespan can be shortened by severe overheating or improper installation.

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.

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