Reinforced head gasket BMW 325i E30 / 525i E34 M20B25

We offer several reinforced head gaskets for the M20B25 engine from ATHENA and COMETIC, whose technical specifications you will find below.

Below (click on the image) you will find the head studs / head bolts for the BMW M20B25 engine:

Technical specification of the OEM gasket

• Bore: 84mm
• Compressed thickness: 1.75mm

Technical specification

• Bore: up to 85.5mm
• Compressed thickness(es) available: 2.00mm
• Gasket type: O-ring
• Reference: 330015R

Designed and manufactured in Italy, Athena reinforced head gaskets are available in two forms:

• MLS: these gaskets are made from several stainless steel sheets stacked and riveted together. The stainless steel sheets are laser-cut for greater precision and receive an elastomer-based surface treatment (NBR or FKM). To achieve optimal sealing, the cylinder bore contours and water/oil passages are stamped/embossed. For the most extreme applications, reinforcement is added around the cylinders.
• O-ring: these gaskets consist of a steel sheet coated with asbestos-free aramid fibre and a stainless steel AISI 304 ring (around the cylinders). A bead of silicone applied at critical points (water and oil passages) ensures maximum sealing of the head gasket. This gasket type is mandatory for heavily turbocharged engines.

Technical specification

• Bore: up to 85mm
• Gasket type: MLS
• Number of layers: 3, then 5 for gaskets from 1.42mm thickness
• Compressed thickness(es) available: 0.69, 0.76, 1.02, 1.14, 1.30, 1.42, 1.52, 1.68, 1.78, 1.91, 2.03, 2.18, 2.34, 2.49, 3.05, 3.56mm
• References: C4394, C4394-027, C4394-030, C4394-036, C4394-040, C4394-045, C4394-051, C4394-056, C4394-060, C4394-066, C4394-070, C4394-075, C4394-080, C4394-086, C4394-092, C4394-098, C4394-120, C4394-140

Founded by Bob Gorman in 1989, Cometic is recognised worldwide as a leader in the design and manufacture of reinforced head gaskets. Like all of the brand's products, they are manufactured in the United States. Cometic reinforced head gaskets are made from several stamped stainless steel sheets held together by rivets. There are three types of Cometic head gaskets:

• MLS: equivalent to Athena MLS gaskets, these multi-layer gaskets (between 3 and 5 stainless steel sheets depending on gasket thickness) feature embossing around the cylinders and fluid passages.

• MLX: this gasket has the same base as the MLS gasket but with added reinforcement (folded sheet) around the cylinders and a special high-temperature coating.

• HP: this is an MLX gasket to which an additional layer has been added, designed to reinforce the sealing of the cylinders (see below)