The Honda 12311-ZG8-000 Cylinder Head Cover is a genuine OEM replacement designed for GX640 horizontal shaft engines, H4518 lawn tractors, and H5518 multi-purpose tractors. As a direct Honda OEM part, this cover is manufactured to the same specification as the original, ensuring a correct fit without adaptation. Honda supersedes parts at serial-number breaks, so verify your machine's serial number against the fitment table before ordering to confirm this is the right cover for your unit. The Cylinder Head Cover seals the top of the engine's valvetrain, keeping oil in and contaminants out.
Key Features
- Genuine OEM Sealing Integrity — manufactured by Honda to match the original cover's sealing surface geometry, maintaining the correct interface between cover and head gasket to prevent oil weepage
- Direct-Fit Replacement — engineered as a drop-in replacement for GX640 engines, H4518 lawn tractors, and H5518 multi-purpose tractors with no rework required
- Serial Number Awareness — Honda issues parts revisions at defined production breaks; always cross-reference your machine's serial number with the fitment table to confirm this cover is correct for your specific unit
- Valvetrain Protection — a properly sealed cylinder head cover keeps the rocker arm chamber free of debris and moisture, preserving oil quality and valvetrain longevity; a cracked or warped cover leads to oil loss and contamination
The cylinder head cover sits atop the engine's cylinder head and encloses the valvetrain — the rocker arms, valves, and related components that control airflow into and out of the combustion chamber. It retains the engine oil that lubricates those moving parts while sealing the assembly against dust, moisture, and debris. When a cylinder head cover cracks, warps, or loses its seal, oil escapes onto hot engine surfaces, creating both a fire risk and an accelerating wear condition for the valvetrain components inside. Replacing a damaged cover promptly with a correct-fitting OEM part restores the sealed environment the valvetrain depends on.
Part Details
| Part Number | 12311-ZG8-000 |
|---|---|
| Brand | Honda |
| Part Type | Genuine OEM |
| Description | Cylinder Head Cover |
Compatibility & Fitment
| Name | Models | Serial Range |
|---|---|---|
| Horizontal Shaft Engine | GX640 | 1000001-1017916 |
| Lawn Tractor | H4518 | All |
| Multi-Purpose Tractor | H5518 | All |
Verify Before You Order
Fitment is machine-number and revision-specific; always confirm your model and serial number against the fitment list.
Why Buy From DHS Equipment
Every part is verified against the manufacturer's part number before it ships, so what you order is what arrives. We carry parts from leading OEM brands and our own DHS Quality Parts line of professional aftermarket components. Need help finding the right part? Our team is available to confirm compatibility whenever you need it. Orders are processed fast to keep your jobs on track. We don't just sell parts. We keep you jobsite ready.
Questions? Contact our team at [email protected] or 866-611-9369 — DHS Equipment is here to help you maintain peak performance.
