Reinforced cylinder head gasket Honda Accord CR-V Civic Odyssey 2.4 K24

The Honda engines covered

The K24 is a family of 2.4 litre petrol engines with four in-line cylinders. This page covers the K24A, K24A2, K24A3, K24A8, K24Z1, K24Y2, K24Z2, K24Z3, K24Z6 and K24Z7, fitted to the Honda models listed below.

The original gaskets carry the part numbers 12251-R40-A01, 12251-RAA-A01, 12251-RAA-A02 and 12251-RAA-J01. Honda publishes neither their bore, their thickness nor their construction. This in-line four takes a single head gasket. Meant for the standard combustion pressure, it gives out once that pressure rises: the head loses clamping load, lifts and coolant reaches a cylinder.

Reinforced cylinder head gaskets

Sealing depends on the fasteners that clamp the head to the block as much as on the gasket. A composite gasket settles permanently above 100 N/mm²; the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and recovers its shape at each combustion.

This page brings together 26 part numbers from Cometic, the American competition gasket maker, for a single construction: MLS, a multilayer steel design. Three gaskets (C14068) have an 88 mm bore, six (C4594) an 87 mm bore and seventeen (C4595) an 89 mm bore; thicknesses run from 0.69 to 3.56 mm, enough to adjust the compression ratio without touching the pistons or the cylinder head. As a rule, the gasket bore chosen is at least 0.5 mm larger than the actual cylinder bore. Each part number is sold individually, one gasket per engine.

Technical specifications

The volume of a gasket is the free space it leaves above each cylinder; it adds to the combustion chamber and reduces the compression ratio. Compare it only at equal bore, here 87 mm for the C4594, 88 mm for the C14068 and 89 mm for the C4595.

Preparation and fitting

Before fitting, check the flatness of the head and block with a straight edge, and have them resurfaced if needed. Cometic supplies these gaskets already coated: do not add any sealant.

Technical guide

The construction offered

Cometic MLS Several embossed stainless steel sheets riveted together. The outer sheets carry active beads around each cylinder and each fluid passage. Moderate clamping is enough to seal and the bore distorts little: a versatile construction, from the tuned naturally aspirated engine to moderate boost.

Choosing bore and thickness

Gasket bore. The Cometic MLS is offered in 87 mm (C4594), in 88 mm (C14068) and in 89 mm (C4595).

Thickness. No thickness is published for the original gaskets 12251-R40-A01, 12251-RAA-A01, 12251-RAA-A02 and 12251-RAA-J01. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

Before choosing less than the original thickness, read with a dial gauge how far the pistons protrude above the block's gasket face: that figure gives the clearance left between piston and head.

The brand

Cometic Gasket, Inc. is an American company set up in 1989 in Concord, Ohio, that designs and makes engine gaskets and sealing parts. It is best known for the custom gasket, cut to the requested bore and thickness and made in the United States from American raw materials.

Advantages over the original gasket

When a reinforced gasket becomes necessary

• Adding forced induction, or raising boost on an already turbocharged engine
• Cylinder rebored beyond what the 87 mm, 88 mm and 89 mm bores of these gaskets covers
• Looking for a compression ratio different from standard, higher or lower
• Engine that has already lost its gasket, or is consuming coolant
• Competition use, where the gasket goes through repeated temperature rises

Vehicle compatibility

OEM part number: 12251-R40-A01, 12251-RAA-A01, 12251-RAA-A02 and 12251-RAA-J01.

Important: the part numbers on this page suit only the K24A, K24A2, K24A3, K24A8, K24Z1, K24Y2, K24Z2, K24Z3, K24Z6 and K24Z7 engines: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its limit, the reinforced one takes over: under higher combustion pressure it holds its shape instead of settling.

When the engine is tuned harder, with livelier camshafts, a higher compression ratio or added boost, the head gasket is the first part of the top end to fail. A reinforced gasket prevents the leak, then a head removal that costs far more than the part.