Head and Cover Gasket Set – Fits Johnson/Evinrude V4 85-140 HP (Replaces 318358, 318335)

$32.40

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Head and Cover Gasket Set – Fits Johnson/Evinrude V4 85-140 HP (Replaces 318358, 318335) is backordered and will ship as soon as it is back in stock.

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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 Head and Cover Gasket Set is a direct-fit replacement for Johnson/Evinrude V4 Crossflow 85–140 HP 2-stroke outboard engines manufactured between 1973 and 1998. It is engineered to meet or exceed original equipment specifications, ensuring a reliable seal for your engine's cylinder head and cover.

The set provides an interchange solution for Johnson/Evinrude parts 318358 and 318335, as well as aftermarket equivalents from Sierra, GLM, Mallory, and Mercury.

Direct replacement for a straightforward installation.
Made from high-quality composite gasket material to ensure a durable seal.
Manufactured to OEM specifications for precise fit and function.

Part Number Matrix

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

Brand	Part Number	Notes
Johnson/Evinrude	318358	Head Gasket
Johnson/Evinrude	318335	Cover Gasket
Sierra	18-2956
Sierra	18-2873-9
GLM	33540
Mallory	9-63828
Mercury	878877	Interchange Part

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Johnson/Evinrude Outboards: Fits a wide range of V4 Crossflow models from 85 HP to 140 HP as detailed in the chart. Note that for models listed as "19xx-Up", verify your specific year against the OEM part number.

For Mercury Outboards: This part is listed as a compatible interchange for Mercury part number 878877. A specific model application list for Mercury is not available, so please confirm compatibility by cross-referencing the part number.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Johnson/Evinrude	85 HP	85	2-Stroke	1973–1995	318358	V4 Crossflow
Johnson/Evinrude	88 HP	88	2-Stroke	1987–Up	318358	V4 Crossflow
Johnson/Evinrude	90 HP	90	2-Stroke	1981–1994	318358	V4 Crossflow
Johnson/Evinrude	100 HP	100	2-Stroke	1979–Up	318358	V4 Crossflow
Johnson/Evinrude	110 HP	110	2-Stroke	1986–1990	318358	V4 Crossflow
Johnson/Evinrude	115 HP	115	2-Stroke	1973–1998	318358	V4 Crossflow
Johnson/Evinrude	135 HP	135	2-Stroke	1973–1976	318358	V4 Crossflow
Johnson/Evinrude	140 HP	140	2-Stroke	1973–1984	318358	V4 Crossflow

Technical Specs

Product Type: Head and Cover Gasket Set
Installation: Direct replacement
Fuel Type: Gasoline
Gasket Material: Composite gasket material
Manufacturing: Manufactured to OEM specifications using the exact same material as the originals

What’s in the Box

1 x Head Gasket (Replaces 318358)
1 x Cover Gasket (Replaces 318335)

Installation Notes

Ensure the engine is completely cool and disconnect the battery before beginning work.
Thoroughly clean the area around the cylinder head and cover to prevent dirt and debris from entering the engine.
Carefully remove the old gaskets. Use a gasket scraper to remove all residual material from the mating surfaces, taking care not to gouge the metal.
Position the new gaskets correctly, ensuring they align with all bolt holes and passages. Do not use sealant unless specifically required by your engine's service manual.
Reinstall all components in the reverse order of removal. Tighten all bolts in the sequence and to the torque values specified by the manufacturer.
After reassembly, reconnect the battery, start the engine, and carefully check for any coolant, fuel, or exhaust leaks around the repaired area.

Troubleshooting & FAQ

How do I know if my head or cover gasket is failing?

Signs of a bad head gasket include engine overheating, a noticeable loss of power, white smoke from the exhaust, or finding milky oil (or oil in the coolant). A failing cover gasket typically causes visible external oil or coolant leaks from the cylinder head cover.

Is sealant required for these gaskets?

These gaskets are typically designed for dry installation. Using RTV or other sealants is generally not recommended unless explicitly specified in your engine’s official service manual, as it can interfere with proper sealing and uniform compression.

What is the difference between the head and cover gaskets in this set?

The head gasket (replaces 318358) creates a critical seal between the cylinder head and the engine block to maintain compression. The cover gasket (replaces 318335) seals the water jacket/cylinder head cover to prevent external coolant leaks.

Is this a complete gasket kit for my engine?

No, this is a specific set containing only the cylinder head gasket and the head cover gasket. A complete powerhead overhaul gasket kit would include many other seals and gaskets required for a full engine rebuild.

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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