Reinforced cylinder head gasket BMW V8 M62B44 540i 740i 840Ci

The BMW engines covered

The M62B44 engine is the petrol V8, 4.4 litres and 32 valves, of the BMW 540i (E39), 540i Touring (E39), 740i and 740iL (E38), 840Ci (E31) and X5 4.4i (E53), detailed in the table below. It has two banks of four cylinders, each with its own gasket.

The original gasket carries the part number 11 12 1 433 473. BMW publishes neither its bore, nor its construction, nor its thickness. It is sized for the standard combustion pressure: once that rises, the clamping load weakens, the head lifts and coolant reaches a cylinder.

Reinforced cylinder head gaskets

Sealing does not depend on the gasket only: it also relies on the bolts or studs that hold the head against the block. With the O-Ring each part has its own role: the stainless steel ring isolates the combustion chamber, the gasket body manages the water and oil passages, and the block requires no machining.

This page presents two part numbers from Athena, an Italian maker of competition gaskets, in a single construction: the O-Ring, a steel sheet faced with aramid fibre and ringed with stainless steel. The V8 needs two gaskets, one per bank: the 330026R for the right bank, the 330027R for the left bank. Their bore is 93.6 mm and their thickness 2.00 mm. Each part number is sold individually.

Technical specifications

Gasket volume is the space that remains above each cylinder. It is added to the combustion chamber and reduces the compression ratio; comparing two gaskets only makes sense at an identical bore.

Preparation and fitting

Before assembly, run a straight edge over the head and the block to check their flatness, and have them resurfaced if needed. Athena supplies this gasket ready for use: do not add any sealing paste.

Technical guide

The construction offered

Athena O-Ring A steel sheet covered with asbestos-free aramid fibre, which follows each cylinder with a stainless steel compression ring. The ring brings the clamping force back onto a narrow band, where the seal is made, and a silicone bead protects the water and oil ducts. The coating is already applied on delivery. This construction resists the highest pressures in the range.

Choosing bore and thickness

Gasket bore. The Athena O-Ring comes in 93.6 mm (330026R for the right bank, 330027R for the left bank), with no other bore.

Thickness. BMW does not publish the thickness of the original gasket: only the dimension taken on the removed gasket is a valid reference. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

With no published original thickness, measure with a dial gauge how far the pistons protrude above the block's gasket face, especially if the removed gasket is thinner than 2.00 mm: this figure gives the clearance left between piston and head.

The brand

Athena S.p.A. is an Italian group specialising in gaskets and engine parts; its main factory is in Alonte, in the Veneto. It has other sites in Spain, the United States, Brazil and India. Car manufacturers fit its multi-layer gaskets as original equipment, and the whole competition range is designed and built in Italy.

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 93.6 mm bore, the largest of the gaskets 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: 11 12 1 433 473.

Important: the part numbers on this page suit the M62B44 engine: each engine needs both, one per cylinder bank.

Why switch to a reinforced gasket?

If the original gasket no longer holds, the reinforced gasket replaces it: under stronger combustion pressure it keeps its shape and does not crush.

As soon as an engine is modified, with a raised compression ratio or added forced induction such as a turbo or a supercharger, the head gasket is the part that fails first on this V8. A reinforced gasket rules out the leak and the head removal that results, together with the matching workshop hours.