Reinforced head gasket VW Audi 1.8 T 20V AEB AGU AMB AUQ AWP BAM BEA

The Volkswagen and Audi engines covered

The 1.8 litre turbocharged inline four-cylinder petrol engines with twenty valves from the Volkswagen group (AEB, AGU, AJH, APH, ARX, ARZ, ATW, AUM, AVC, AWD, AWT, AWW, BJX, BKF, BKV, CFMA, AYP, AMB, AWM, AJQ, APP, ARY, ATC, AUQ, AWP, BEK, BNU, BEX, BVR, AMU, AMK, BAM and BEA) make up this family. They power the Volkswagen Golf IV, Bora, New Beetle, Passat B5 and B5.5, Sharan and Polo IV as well as the Audi A3, A4, A6, TT and S3 in the table below; codes BKV, CFMA and AYP appear in the survey only on other brands of the group. One cylinder head covers all four cylinders: the gasket is sold singly, one per engine.

The manufacturer part number of the standard gasket is 058 103 383, in suffixes H, J and K; neither the bore, nor the thickness, nor the construction is published. This gasket is sized for the original combustion pressure; as soon as it rises, the clamp load fades, the head lifts and coolant seeps into a cylinder.

Reinforced cylinder head gaskets

The gasket is not everything: the bolts that clamp the head to the block count as much as it does, and new bolts are required at every refit. A composite gasket settles for good above 100 N/mm²; the 301 stainless steel of MLS gaskets holds 517 N/mm², 5 times more, and recovers its shape at every combustion.

This page presents the part numbers of Cometic, an American maker of racing gaskets, in a single construction, the multi-layer MLS, with three gasket bores: 81, 82 and 85 mm. Thickness runs from 0.69 to 3.56 mm, so the compression ratio can be set without working on the pistons or the 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 piston; it adds to the combustion chamber and lowers the compression ratio. Only compare gaskets of the same bore, here 81, 82 or 85 mm.

Preparation and fitting

Check the flatness of the head and of the block with a straight edge before fitting, and have any distorted surface machined. Use no sealing paste: the Cometic gasket arrives already coated, and an excess of paste would upset the clamp load.

Technical guide

The construction offered

Cometic MLS A stack of embossed stainless steel sheets riveted to one another. The outer sheets show active raised beads around each cylinder and each fluid passage: a moderate clamp load is enough to seal, without distorting the bore. A versatile construction, from the tuned naturally aspirated engine to reasonable boost.

Choosing bore and thickness

Gasket bore. The Cometic MLS comes in 81 mm (H3078SP9092S), in 82 mm (C4558 series) and in 85 mm (C4559 series).

Thickness. The manufacturer publishes no standard thickness: rely on the measurement of the removed gasket. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

Since the standard figure is not published, use a dial gauge to measure how far the pistons stand proud of the block deck: this reading gives the clearance left between piston and head, above all if you pick a thickness smaller than that of the removed gasket.

The brand

Cometic Gasket, Inc. is an American maker of gaskets and sealing solutions for engines, founded in 1989 in Concord, Ohio. It made its name with the made-to-measure gasket, cut to the bore and thickness requested, built entirely 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 bore of the gaskets offered (81, 82 and 85 mm) 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: 058 103 383 H ; 058 103 383 J ; 058 103 383 K ; 058 103 383.

Important: the gaskets on this page are listed for the 1.8 turbo engines of the survey below, at Volkswagen and Audi. For any other vehicle, check the engine code before ordering.

Why switch to a reinforced gasket?

When the standard gasket gives up, the reinforced gasket takes over: under a higher combustion pressure, the stainless steel sheets of the MLS do not crush and the gasket holds its shape.

On a boosted engine, raising turbo pressure or the compression ratio loads the head gasket first, the weak point of the top end. A reinforced gasket avoids the leak and the head removal that follows, a job far dearer than the part: you might as well fit it during the build.