Manifold to Crankcase Gasket – Fits Bombardier/Johnson/Evinrude/OMC (Replaces 315578)

$6.00

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Product Details

This aftermarket Manifold to Crankcase Gasket is designed for Johnson, Evinrude, and OMC outboard engines, typically fitting 40-75 HP 2-Stroke models from the 1960s through the 1990s. It serves as a crucial seal between the intake manifold and the crankcase to prevent air leaks.

It is a direct replacement for several OEM and aftermarket part numbers, including OMC 315578, Sierra 18-0424, and Mallory Marine 9-60437.

Designed for direct replacement installation.
Resistant to heat, pressure, and gasoline.
Seals the intake system to ensure proper engine performance.

Part Number Matrix

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

Brand	Part Number
OMC	315578 / 0315578
Sierra	18-0424
Mallory Marine	9-60437
GLM	34790
Aqua Power	1709

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This gasket is known to fit various Johnson and Evinrude 2-stroke outboards. Verify your specific model's part requirements before ordering.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Johnson/Evinrude	Various	50	2-Stroke	1971+	315578	Intake manifold gasket

Technical Specs

Product Type: Manifold to Crankcase Gasket
Installation: Direct replacement
Fuel Type: Gasoline
Housing Material: Gasket material (likely composite)
Dimensions: 11.25" x 6.0" x 1.13"
Warranty: 30 day (Aftermarket); None (OEM)
Other Technical Attributes: Heat, pressure, and chemical resistant

What’s in the Box

1 x Manifold to Crankcase Gasket (315578/0315578)

Installation Notes

Professional installation is recommended. The following are general, model-agnostic steps:

Disconnect the battery and ensure the engine is cool.
Relieve fuel system pressure and remove the engine cover/cowling.
Carefully detach fuel lines and electrical connectors from the intake manifold.
Unbolt and remove the intake manifold from the crankcase.
Remove the old gasket and thoroughly clean both mating surfaces of any residue or old material.
Position the new gasket correctly on the crankcase.
Reinstall the intake manifold, tightening bolts to the manufacturer's specified torque sequence and values.
Reconnect all fuel lines and electrical connectors.
Start the engine and carefully check for any air or fuel leaks around the gasket area.

Troubleshooting & FAQ

How do I know if this gasket fits my engine?

Verify that your engine's original part number matches one of the cross-reference numbers listed in the Part Number Matrix. The compatibility table provides general guidance, but checking the specific part number for your model and year is the most reliable method.

What are the signs of a failing manifold gasket?

Common symptoms include a rough or unstable idle, difficulty starting, reduced engine power, engine backfiring, or an audible whistling/sucking sound from the engine bay, which indicates an air (vacuum) leak.

Can I reuse my old gasket?

No. Gaskets are single-use components designed to compress and seal. Once removed, they lose their sealing ability and must be replaced with a new one to prevent leaks.

Is any sealant required with this gasket?

Generally, this type of gasket is designed to be installed dry. Applying sealants can sometimes interfere with its function unless specifically required by your service manual. Always consult your engine's service manual for the correct procedure.

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

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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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