Head and Cover Gasket Set for Johnson/Evinrude Outboards – Replaces 318358 and 318335
Head and Cover Gasket Set for Johnson/Evinrude Outboards – Replaces 318358 and 318335 is backordered and will ship as soon as it is back in stock.
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Head and Cover Gasket Set for Johnson/Evinrude Outboards – Replaces...
Head and Cover Gasket Set for Johnson/Evinrude Outboards – Replaces 318358 and 318335 is backordered and will ship as soon as it is back in stock.
Product Details
This aftermarket Head and Cover Gasket Set is designed for selected Johnson/Evinrude outboard applications using the specified head and water-cover gasket references. The set includes replacement gaskets corresponding to Johnson/Evinrude part numbers 318358 and 318335.
The supplied aftermarket references are Sierra Marine 18-2956 for the head gasket and Sierra Marine 18-2873 for the water-cover gasket. Confirm both gasket shapes and the original engine part numbers before ordering.
- Replacement set for a head gasket and a water-cover gasket.
- Includes two pieces of each gasket type.
- Aftermarket replacement parts; not manufactured by Johnson, Evinrude, OMC, BRP, or Sierra Marine.
- Use the OEM reference numbers and gasket dimensions to verify suitability for your engine.
Part Number Matrix
The following references describe the component relationships used for this set. They are not a substitute for checking the exact engine model and service-manual part number.
| Component | Manufacturer Reference | Aftermarket Reference | Description |
|---|---|---|---|
| Head gasket | Johnson/Evinrude 318358 | Sierra Marine 18-2956 | Head gasket replacement |
| Water-cover gasket | Johnson/Evinrude 318335 | Sierra Marine 18-2873 | Water jacket or water-cover gasket replacement |
Engine and Model Compatibility
Fitment is determined by the gasket reference and the exact engine configuration. Catalog evidence associates reference 318358 with selected Johnson/Evinrude V4 90-degree two-stroke applications, including:
| Engine family | Stroke | Years shown in catalog evidence | Reference | Important condition |
|---|---|---|---|---|
| V4 90-degree Crossflow | 2-Stroke | 1973–1994 | 318358 | Confirm the exact engine model and gasket profile. |
| V4 90-degree Loopcharged | 2-Stroke | 1988–1999 | 318358 | Confirm the exact engine model and gasket profile. |
The available company record does not provide a complete horsepower, model-year, serial-number, shaft-length, or individual-engine fitment list for this set. Do not rely on a broad horsepower range alone. Match both supplied gasket references to your engine's parts diagram or service manual before installation.
Technical Specifications
- Product Type
- Head and cover gasket set
- Application
- Selected Johnson/Evinrude outboard applications
- Head Gasket Reference
- Johnson/Evinrude 318358; aftermarket reference Sierra Marine 18-2956
- Water-Cover Gasket Reference
- Johnson/Evinrude 318335; aftermarket reference Sierra Marine 18-2873
- Quantity
- Two head gaskets and two water-cover gaskets
- Installation
- Replacement installation according to the applicable engine service manual
What's in the Box
- 2 x head gaskets corresponding to Johnson/Evinrude 318358
- 2 x water-cover gaskets corresponding to Johnson/Evinrude 318335
Installation Notes
- Confirm the exact engine model, year, serial-number range, and the two original gasket references before disassembly.
- Allow the engine to cool completely and follow the safety procedures in the applicable service manual.
- Remove the old gaskets and carefully clean all mating surfaces without gouging the cylinder head, cover, or block.
- Compare each replacement gasket with the removed gasket and verify all bolt holes, water passages, and orientation.
- Install the gaskets in the correct locations. Do not apply sealant unless the engine manufacturer's service manual specifically requires it.
- Reassemble using the manufacturer's tightening sequence and torque specifications.
- After assembly, inspect for water, exhaust, or compression leaks and complete the required operational checks.
Troubleshooting and FAQ
Which gaskets are included?
This set includes two head gaskets corresponding to 318358 and two water-cover gaskets corresponding to 318335.
Is this a complete engine gasket kit?
No. This is a specific head-and-cover gasket set. It does not include every gasket or seal required for a powerhead overhaul or complete engine rebuild.
Does the set fit every Johnson/Evinrude V4 engine?
No. The references are associated with selected V4 applications, but model, year, serial range, engine configuration, and gasket profile must be checked before purchase. A horsepower range by itself is not sufficient confirmation.
How do I identify the head gasket?
The head gasket corresponds to Johnson/Evinrude reference 318358 and aftermarket reference Sierra Marine 18-2956. Confirm the part number and physical profile against your original gasket or parts diagram.
How do I identify the water-cover gasket?
The water-cover gasket corresponds to Johnson/Evinrude reference 318335 and aftermarket reference Sierra Marine 18-2873. Confirm the part number and physical profile before installation.
Is sealant required?
Use the installation method specified in the applicable engine service manual. Do not add RTV or other sealant unless the manual expressly calls for it.
Is this an OEM product?
No. This is an aftermarket replacement set. Johnson, Evinrude, OMC, BRP, and Sierra Marine references are provided only for identification and cross-reference purposes.
Safety and Important Information
- Verify the original part numbers, gasket shape, engine model, year, and serial-number range before ordering.
- Do not install a gasket that differs in shape, thickness, bolt-hole pattern, or water-passage layout from the required part.
- Follow the applicable manufacturer's service manual for disassembly, torque values, sealant requirements, and testing.
- Professional installation is recommended when cylinder-head or water-cover service is required.
About Sea Sierra
- Marine Parts Selection — Replacement components for maintenance and repair of marine engines and systems.
- Reference-Based Ordering — Product information is organized around manufacturer references and component applications.
- Practical Support — Verify fitment details before ordering to help ensure the correct replacement part.
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