The Honda 12251-Z1C-801 Cylinder Head Gasket (Thai Leakless) is a genuine OEM replacement designed for GX390 horizontal shaft engines and Honda EB and EM series generators, including the EB3800, EB4000, EB5000, EB6500, EM3800, EM4000, EM5000, and EM6500. As a genuine Honda component, this cylinder head gasket is manufactured to the same specification as the original part, ensuring a proper seal between the cylinder head and engine block. Always verify your unit's serial number against the fitment table before ordering, as Honda periodically supersedes parts at specific serial breaks.
Key Features
- OEM Cylinder Head Sealing — manufactured by Honda to deliver the correct combustion chamber seal, maintaining compression and preventing coolant or oil migration past the head joint
- Thai Leakless Specification — this variant carries Honda's Thai Leakless designation, identifying the specific gasket grade for this application; match this qualifier to your engine's parts diagram before purchasing
- Broad Fitment — a single genuine OEM part covering the GX390 horizontal shaft engine and eight EB and EM series generators, including the EB3800, EB4000, EB5000, EB6500, EM3800, EM4000, EM5000, and EM6500
- Serial Number Verification Recommended — Honda supersedes head gaskets at production breaks, so cross-check your machine's serial number against the compatibility table to confirm part number 12251-Z1C-801 is correct for your unit
- Compression Integrity — a failed or worn cylinder head gasket allows combustion pressure to escape, leading to power loss, hard starting, and potential internal engine damage; replacing it with the correct OEM part restores full compression and engine output
The cylinder head gasket sits between the cylinder head and the engine block, forming a critical seal that contains combustion pressure and keeps oil and any condensation from passing between the two mating surfaces. When this gasket fails — through heat cycling, improper torque, or age — the engine loses compression, may produce white or blue exhaust smoke, and will run poorly or refuse to start. Replacing it with the correct genuine OEM gasket, torqued to Honda's specification, restores the combustion seal and returns the engine to full working condition.
Part Details
| Part Number | 12251-Z1C-801 |
|---|---|
| Brand | Honda |
| Part Type | Genuine OEM |
| Description | Cylinder Head Gasket (Thai Leakless) |
Compatibility & Fitment
| Name | Models | Serial Range |
|---|---|---|
| Generator | EB3800, EB4000, EB5000, EB6500, EM3800, EM4000, EM5000, EM6500 | 1337117-9999999 |
| Horizontal Shaft Engine | GX390 | 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.
