Sierra 18-0664 Valve Cover Gasket, Replaces 909529, Fits GM 305/350 5.0L & 5.7L Engines

The Sierra 18-0664 is a valve cover gasket engineered to seal the valve cover against the cylinder head on GM 305/350 cubic-inch marine engines, including 5.0L and 5.7L applications. It creates the seal that keeps oil inside the valve cover assembly and prevents leaks at the cylinder head mating surface, a common failure point on inboard and sterndrive engines that see extended run time and heat cycling.

Each 18-0664 is sold as a pack of 2, giving you both gaskets needed for a V8 engine's left and right valve covers in a single purchase. Replacing worn valve cover gaskets is a routine maintenance step during valve cover removal for inspection, tappet adjustment, or general engine service, and using a properly sized replacement gasket helps ensure a leak-free reseal.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-0664
• Product Type: Valve Cover Gasket
• Package Quantity: 2 gaskets per pack
• Fits: GM 305/350, 5.0L & 5.7L engines
• Weight: 0.29 pounds
• UPC: 808282237189

Fitment

• GM 305/350 cubic-inch engines
• 5.0L and 5.7L engines

Replaces (OEM)

• 909529

Frequently Asked Questions

What engines does the Sierra 18-0664 fit? The Sierra 18-0664 valve cover gasket fits GM 305/350 cubic-inch engines, including 5.0L and 5.7L versions.

Is 18-0664 the same gasket as OEM 909529? Yes, the Sierra 18-0664 replaces OEM part number 909529 and is designed as a direct-fit substitute for it.

How many gaskets are included with part 18-0664? Part 18-0664 is packaged as a set of 2 gaskets, enough to cover both valve covers on a V8 engine.

How much does the 18-0664 gasket weigh? The Sierra 18-0664 valve cover gasket has a shipping weight of 0.29 pounds for the 2-gasket pack.

Do I need one or two gaskets for my engine? A V8 engine has two valve covers, so you need two gaskets, which is exactly what comes in one pack of the Sierra 18-0664.

Is this a genuine Sierra part? Yes, this gasket is manufactured and sold under the Sierra brand as part number 18-0664.

Can I reuse a valve cover gasket after removing the valve cover? Gaskets are generally not reused once removed since they lose their sealing compression; installing a new Sierra 18-0664 gasket at reassembly gives the most reliable seal.

What is the function of the valve cover gasket on a GM 305/350 engine? It seals the joint between the valve cover and the cylinder head, part number 18-0664 being the gasket sized for GM 305/350, 5.0L and 5.7L engines.

Does the 18-0664 come as a full gasket set or just the valve cover gasket? The Sierra 18-0664 is specifically a valve cover gasket, sold two to a pack, and is not a complete engine gasket set.

What OEM number should I cross-reference when ordering 18-0664? Sierra 18-0664 cross-references to OEM part number 909529.