Cometic C4251-030 MLS Head Gasket – Honda D15Z1/D16Y5/D16Y7/D16Y8/D16Z6 – 75.5mm Bore, .030″ Thickness

Why Choose an MLS Head Gasket for Your Honda D-Series?

Honda’s D-series engines have earned a reputation for reliability, affordability, and impressive aftermarket support. However, proper cylinder head sealing becomes particularly important when rebuilding an aging engine or increasing cylinder pressure through performance modifications.

The Cometic C4251-030 uses layered steel construction rather than a conventional composite gasket design.

MLS head gaskets are engineered to accommodate small amounts of movement between the cylinder head and engine block while maintaining sealing pressure around the combustion chambers.

Potential advantages include improved durability under appropriate operating conditions, resistance to combustion pressure, and consistent gasket thickness.

Important: MLS gaskets are sensitive to surface finish and flatness. They are not a substitute for repairing a warped cylinder head, damaged block deck, or inadequate cylinder head clamping.

Honda Civic and Civic del Sol Vehicle Fitment

Cometic lists this head gasket for the following Honda engine families and model years. Fitment depends on the engine installed, not simply the vehicle badge.

Fitment note: Confirm the engine code and actual cylinder bore before ordering. The 75.5mm measurement refers to the gasket’s combustion opening, not a universal fitment for every D-series engine.

FYI: Is a 75.5mm Head Gasket Right for Your D16 Engine?

Many Honda D16 engines have a nominal factory cylinder bore of 75.0mm. This Cometic gasket features a 75.5mm opening, providing an additional 0.5mm of gasket bore diameter.

The correct gasket bore must accommodate the finished cylinder bore without exposing the gasket’s combustion sealing edge.

For a modified D-series engine, verify the actual cylinder diameter, piston-to-head clearance, deck condition, and desired compressed gasket thickness.

A thinner gasket can affect combustion chamber volume and compression ratio, but the exact change depends on the engine’s complete dimensions.

How to Prepare Your Honda D-Series for an MLS Head Gasket

A successful head gasket replacement starts long before the new gasket touches the engine block.

1. Diagnose the original failure. Identify overheating, cooling-system pressure problems, combustion leakage, or other causes before disassembly.

2. Inspect the cylinder head. Check for warpage, cracks, corrosion, and damage around the combustion chambers.

3. Check the block deck. Confirm flatness and the surface finish required for MLS sealing.

4. Clean the mating surfaces. Remove old gasket material without gouging the aluminum cylinder head or block deck.

5. Inspect the head bolts or studs. Use appropriate fasteners and follow the applicable manufacturer’s installation instructions.

6. Install the gasket correctly. Position the gasket using the locating dowels and follow the engine-specific tightening sequence.

7. Refill and bleed the cooling system. Confirm proper operating temperature and inspect for leaks.

Cometic MLS head gaskets are designed for installation without additional sealing compounds unless specifically directed by the manufacturer.

Frequently Asked Questions

Does the Cometic C4251-030 fit a Honda D16Y8 VTEC engine?

Yes. Cometic identifies the D16Y8 among its supported applications, including applicable 1996–2000 Honda Civic EX models.

Can this head gasket be used on a turbocharged D16Z6?

It can be considered for a properly engineered turbocharged build. However, boost pressure, combustion tuning, head clamping, deck preparation, and engine condition all influence sealing reliability. No specific boost-pressure rating is established by this product’s specifications.

Is the Cometic C4251-030 a three-layer head gasket?

Yes. Cometic specifies three MLS layers, a round 75.5mm bore, and .030-inch compressed thickness.

Will this gasket fix an overheating Honda Civic?

Only if a failed head gasket is the confirmed cause and any underlying problems are corrected. A malfunctioning radiator, thermostat, cooling fan, or damaged cylinder head can cause continued overheating even after gasket replacement.

Does this product include head bolts or a complete gasket kit?

No. The listed package contains one cylinder head gasket. Additional components should be purchased separately as required.

Restore Reliable Cylinder Head Sealing with Cometic

When rebuilding a Honda D15Z1 or D16-series engine, gasket selection deserves the same attention as piston clearance, cylinder head condition, and fastener preparation.

The Cometic C4251-030 MLS Cylinder Head Gasket delivers a precision-engineered, three-layer steel sealing solution with a 75.5mm gasket bore and .030-inch compressed thickness for compatible Honda applications.

Choose the right dimensions, prepare the engine correctly, and give your Honda D-series build a solid foundation.

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