Reinforced cylinder head gasket BMW V8 M60B40 540i 740i 840i

The BMW engines covered

The M60B40 engine is the petrol V8, 4.0 litres and 32 valves, of the BMW 540i (E34), 540i Touring (E34), 740i and 740iL (E32 and E38) and 840i (E31), 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 1 736 315. 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

The gasket is not the whole story: sealing also depends on the fasteners that pull the head down onto the block. The O-Ring divides the task: the stainless ring alone closes off the combustion chamber, the body of the gasket looks after the water and oil passages, and the block face needs 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 330024R for the right bank, the 330025R for the left bank. Their bore is 90.6 mm and their thickness 2.00 mm. Each part number is sold individually.

Technical specifications

Gasket volume means the space left open above each cylinder. It adds to the combustion chamber and lowers the compression ratio; two gaskets are only comparable at the same bore.

Preparation and fitting

Before assembly, check the flatness of the head and the block with a straight edge, and have them resurfaced if necessary. Athena supplies this gasket ready to install: no sealing paste should be added.

Technical guide

The construction offered

Athena O-Ring A steel sheet covered with asbestos-free aramid fibre, surrounding each cylinder with a stainless steel compression ring. The ring concentrates the clamping load on a narrow band, where the seal is made, and a silicone bead protects the water and oil passages. The coating is already applied on delivery. This construction withstands the highest pressures in the range.

Choosing bore and thickness

Gasket bore. The Athena O-Ring comes in 90.6 mm (330024R for the right bank, 330025R for the left bank), with no other bore.

Thickness. BMW gives no thickness for the original gasket: only the figure measured on the removed gasket applies. 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, use a dial gauge to measure how far the pistons stand above the block's gasket face, especially if the removed gasket is thinner than 2.00 mm: it gives the clearance left between piston and head.

The brand

Athena S.p.A. is an Italian group making gaskets and engine parts, whose main factory is in Alonte, in the Veneto. It also has sites in Spain, the United States, Brazil and India. Car manufacturers fit its multi-layer gaskets as original equipment, and the competition range is designed and built entirely 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 90.6 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 1 736 315.

Important: the part numbers on this page suit the M60B40 engine: each engine needs both, one per cylinder bank.

Why switch to a reinforced gasket?

Once the original gasket reaches its limit, the reinforced gasket carries on: under higher combustion pressure it holds its shape and does not compress.

As soon as the engine is tuned, with a raised compression ratio or added forced induction such as a turbo or a supercharger, the head gasket is the first part to fail on this V8. A reinforced gasket avoids the leak and the head removal that follows, together with the workshop hours and the repair costs that come with it.