Reinforced head gasket Honda Jazz Civic CR-Z 1.2 1.3 1.5 L12B1 L13Z1 LDA2 LEA1

The Honda engines covered

The petrol engines LEA2, L13Z1, L13Z4, L15Z1, L15Z2, LDA2, LDA3, LEA1, LEA3, L12B1 and L12B2, four-cylinders of 1.2 to 1.5 litres, power the Honda Jazz, Civic, Insight, CR-Z, City, Mobilio and BR-V, some in IMA hybrid form.

The original part number on record is 12251-RB0-004. The manufacturer publishes neither its bore, nor its construction, nor its thickness.

Reinforced cylinder head gaskets

Sealing is not down to the gasket alone: the fasteners that clamp the head onto the block contribute just as much. A composite gasket gives up for good beyond 100 N/mm², whereas the 301 stainless steel of an MLS gasket holds 517 N/mm² and regains its shape after every combustion. On these Hondas, replace the head bolts as the workshop manual advises.

This page presents the part number from Athena, an Italian maker of racing gaskets, in one construction only: the MLS, a multilayer stainless steel gasket. Its bore is 74.5 mm and its thickness 0.70 mm. As a rule, the gasket bore must exceed that of the cylinders by at least 0.5 mm. It is sold individually: a single gasket fits one engine.

Technical specifications

A gasket's volume is the space it leaves free above each cylinder. That space joins the combustion chamber and lowers the compression ratio; only gaskets of the same bore can be compared. Here, the bore offered is 74.5 mm.

Preparation and fitting

Before fitting, check the flatness of the head and block with a straight edge and have them resurfaced if needed. Athena supplies this gasket ready to fit: apply no sealing paste. On a Honda aluminium head, this check is repeated at every rebuild.

Technical guide

The construction offered

Athena MLS Several layers of AISI 301 stainless steel, laser cut, stamped and then riveted together. Around each cylinder, a layer folded over on itself, the Gas Stopper, concentrates the clamping load on the combustion chamber, while beads block the water and oil passages. The outer layers carry a two-coat finish: the first withstands high temperatures and fills small irregularities of the block and head, the second, silicone based, keeps the gasket from sticking at removal. It is Athena's all-steel answer, from the tuned naturally aspirated engine to moderate forced induction. Here, the MLS is offered in 74.5 mm and 0.70 mm.

Choosing bore and thickness

Gasket bore. The Athena MLS exists in 74.5 mm (338581R), with no other bore.

Thickness. The manufacturer supplies no thickness for the original gasket. For these Honda engines, no value is released. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

With no known original thickness, use a dial gauge to read how far the pistons rise above the block face, especially if the removed gasket is thicker than 0.70 mm: that figure gives the clearance left between piston and head. On these engines, the measurement is made with a dial gauge, head removed.

The brand

Athena S.p.A. is an Italian maker of gaskets and engine components, established in Alonte, in Veneto, where its head office and main plant stand. It also has sites in Spain, the United States, Brazil and India. Several carmakers fit its multilayer gaskets on the assembly line, and its entire racing range is designed and built in Italy. Part number 338581R is the one on this page.

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 74.5 mm bore of the gasket offered 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-RB0-004.

Important: the part number on this page suits the LEA2, L13Z1, L13Z4, L15Z1, L15Z2, LDA2, LDA3, LEA1, LEA3, L12B1 and L12B2 engines: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket is no longer enough, the reinforced gasket takes over: under higher combustion pressure it keeps its shape instead of being crushed. These Honda engines find here a gasket with a 74.5 mm bore.

Turbo, supercharger or a raised compression ratio: the head gasket is the first part stressed, the weak point of the top end. A reinforced gasket prevents the leak, and the head removal that goes with it costs well above the gasket. This holds for a Jazz or a Civic as for any hard-driven engine.