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2.3L 16v - B235
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2.3L 16v - B235
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Reinforced Cometic head gasket, in MLS. Sold individually, one gasket per engine.
The Saab B205E, B205L and B205R petrol engines of 2.0 litres, and the B235E, B235L and B235R of 2.3 litres, have sixteen valves. They are fitted to the Saab 9-3 (hatchback and convertible) and 9-5 (saloon and estate) models listed below.
This original gasket carries the part number 59 55 174. Its bore is 91 mm. Saab publishes neither its construction nor its thickness. Each engine takes a single one. It is designed for standard combustion pressure: when that pressure increases, the clamping load weakens, the cylinder head lifts and coolant seeps into a cylinder.
The seal does not come from the head gasket alone: it rests on the fasteners, which clamp the cylinder head to the block. Beyond 100 N/mm² of admissible stress, a composite gasket is crushed for good, whereas the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and regains its shape after every combustion.
This page brings together the part numbers of Cometic, an American maker of racing gaskets, for a single construction: the multi-layer steel MLS. Every gasket has a 91 mm bore, like the original gasket, and thicknesses from 0.69 to 3.56 mm, enough to adjust the compression ratio without touching the pistons or the cylinder 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.
| Gasket bore OEM 91 mm | Thickness | Gasket volume | Gasket type OEM not specified | Brand | Part number OEM 59 55 174 |
| 91 mm | 0.69 mm | 4.49 | MLS | Cometic | C4973-027 |
| 91 mm | 0.76 mm | 4.94 | MLS | Cometic | C4973-030 |
| 91 mm | 0.91 mm | 5.92 | MLS | Cometic | C4973-036 |
| 91 mm | 1.02 mm | 6.63 | MLS | Cometic | C4973-040 |
| 91 mm | 1.14 mm | 7.41 | MLS | Cometic | C4973-045 |
| 91 mm | 1.30 mm | 8.46 | MLS | Cometic | C4973-051 |
| 91 mm | 1.42 mm | 9.24 | MLS | Cometic | C4973-056 |
| 91 mm | 1.52 mm | 9.89 | MLS | Cometic | C4973-060 |
| 91 mm | 1.68 mm | 10.93 | MLS | Cometic | C4973-066 |
| 91 mm | 1.78 mm | 11.58 | MLS | Cometic | C4973-070 |
| 91 mm | 1.91 mm | 12.42 | MLS | Cometic | C4973-075 |
| 91 mm | 2.03 mm | 13.20 | MLS | Cometic | C4973-080 |
| 91 mm | 2.18 mm | 14.18 | MLS | Cometic | C4973-086 |
| 91 mm | 2.34 mm | 15.22 | MLS | Cometic | C4973-092 |
| 91 mm | 2.49 mm | 16.19 | MLS | Cometic | C4973-098 |
| 91 mm | 3.05 mm | 19.84 | MLS | Cometic | C4973-120 |
| 91 mm | 3.56 mm | 23.15 | MLS | Cometic | C4973-140 |
Gasket volume is the space it leaves free above each cylinder. That space adds to the combustion chamber: the larger it is, the more the compression ratio falls. Make this comparison only between gaskets of the same bore.
| Fasteners | Engines | Tightening torque |
| Original cylinder head bolts | B205E, B205L, B205R, B235E, B235L, B235R | not published by the manufacturer |
Before fitting the gasket, check with a straight edge that the cylinder head and block are flat, and have them machined if needed. No sealing paste is to be used: Cometic supplies these gaskets already coated.
 | Cometic MLS A stack of stamped stainless steel sheets, joined by rivets. The outer sheets carry active beads around each cylinder and each fluid passage. A moderate tightening torque is enough to seal, and the bore distorts very little. It is the versatile solution, from the tuned naturally aspirated engine to moderate forced induction. |
Gasket bore. The Cometic MLS is offered in 91 mm (C4973), in that bore only.
Thickness. Saab does not publish the thickness of the original gasket. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.
| Your goal | Thickness to choose |
| Keep the original compression ratio | Original thickness not published by the manufacturer: read the one on the removed gasket and take the nearest value offered |
| Skimmed cylinder head, make up the lost height | The offered value nearest to the thickness read on the original gasket + the material removed |
| Forced induction build, lower the ratio | A thickness greater than the one read on the original gasket at removal |
| Naturally aspirated build, raise the ratio | A thickness smaller than the one read on the original gasket at removal, down to 0.69 mm, the smallest offered |
If the chosen thickness is below the original one, measure with a dial gauge how far the pistons stand above the block: that value gives the clearance left between piston and head.
 | Cometic Gasket, Inc., an American maker of engine gaskets and sealing solutions, began in 1989 in Concord, Ohio. Its speciality is the custom gasket, cut to the bore and thickness wanted. All its production stays in the United States and uses American materials. |
| Criterion | Original gasket 59 55 174 | Reinforced gaskets |
| Construction | Construction not stated by the manufacturer | Multi-layer stainless steel (MLS) |
| Gasket bore | 91 mm | 91 mm |
| Thicknesses available | thickness not published by the manufacturer | 0.69 to 3.56 mm, 17 values |
| Compression ratio adjustment | None | Through the thickness chosen |
| Resistance to overpressure | Limited to standard output | Designed for forced induction |
| Model | Engine code | Power | Years |
| 9-3 (YS3D) 2.0 | B205E | 150 and 185 hp | 1998-2002 |
| 9-3 Cabriolet 2.0 | B205E | 150 and 185 hp | 1998-2003 |
| 9-5 (YS3E) 2.0 t | B205E | 150, 179 and 192 hp | 1997-2009 |
| 9-5 Break (YS3E) 2.0 t | B205E | 150, 179 and 192 hp | 1998-2009 |
| 9-3 (YS3D) 2.0 | B205L | 185 hp | 1998-2002 |
| 9-3 Cabriolet 2.0 | B205L | 185 hp | 1998-2003 |
| 9-5 (YS3E) 2.0 t | B205L | 185 hp | 2000-2009 |
| 9-5 Break (YS3E) 2.0 t | B205L | 185 hp | 2000-2001 |
| 9-3 (YS3D) 2.0 | B205R | 205 hp | 1999-2002 |
| 9-3 Cabriolet (YS3D) 2.0 Turbo | B205R | 205 hp | 1999-2003 |
| 9-5 (YS3E) 2.3 t | B235E | 170, 182, 185 and 210 hp | 1997-2009 |
| 9-5 Break (YS3E) 2.3 t | B235E | 170 and 185 hp | 1998-2009 |
| 9-5 (YS3E) 2.3 | B235L | 203 and 220 hp | 2003-2009 |
| 9-5 Break (YS3E) 2.3 | B235L | 203 and 220 hp | 2003-2009 |
| 9-3 (YS3D) 2.3 | B235R | 224 and 230 hp | 1998-2002 |
| 9-3 Cabriolet (YS3D) 2.3 | B235R | 224 and 230 hp | 1999-2003 |
| 9-5 (YS3E) 2.3 | B235R | 207, 230, 233, 250, 256, 260 and 305 hp | 1999-2009 |
| 9-5 Break (YS3E) 2.3 | B235R | 207, 210, 230, 233, 250, 260 and 305 hp | 1999-2009 |
OEM part number: 59 55 174.
Important: the part numbers on this page fit only the B205E, B205L, B205R, B235E, B235L and B235R engines: check your vehicle's engine code before placing an order.
When the original gasket reaches the end of its capacity, the reinforced gasket takes over: even under higher combustion pressure it keeps its shape instead of being crushed.
As soon as power climbs, with a supercharger, a turbo or a raised compression ratio, the head gasket is the first part to fail in the top end. Opting for a reinforced gasket therefore means choosing reliability: you spare yourself the failure and the cylinder head removal that comes with it.
