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2.0L 16v - Duratec
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2.0L 16v - Duratec
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Reinforced Cometic MLS head gasket for Ford Duratec and Mazda LF-DE. Sold individually.
The 2.0-litre Ford Duratec is the 16-valve DOHC inline four-cylinder petrol engine of the Focus II, C-MAX, Mondeo IV, Galaxy and S-MAX; at Mazda, it carries the code LF-DE (Mazda 3, 5 and 6). This page also covers its 2.3-litre version in the Ranger (T23HDEX): these engines take the same reinforced cylinder head gaskets.
On the Mazda LF-DE, the original gasket carries part number LF01-10-271, or L309-10-271 and LF02-10-271 depending on the version. It is a multi-layer steel (MLS) gasket with a 89 mm bore, whose thickness Mazda does not publish. It is sized for standard combustion pressure: when that pressure rises, clamping load drops, the cylinder head lifts, and coolant passes into a cylinder.
A cylinder head gasket does not create the seal on its own: it holds because the fasteners clamp the head against the block. A composite gasket is crushed for good beyond 100 N/mm² of admissible stress, whereas the 301 stainless steel of the MLS gaskets withstands 517 N/mm², 5 times more, and springs back at every combustion.
This page offers the part numbers from Cometic, a racing manufacturer, in MLS multi-layer steel construction. Gasket bores run from 89.5 to 92 mm, covering the standard block as well as the rebored block, and thicknesses from 0.46 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 89 mm | Thickness | Gasket volume | Gasket type OEM MLS | Brand | Part number OEM LF01-10-271 |
| 89.5 mm | 0.46 mm | 2.89 | MLS | Cometic | C5843-018 |
| 89.5 mm | 0.69 mm | 4.34 | MLS | Cometic | C5843-027 |
| 89.5 mm | 0.76 mm | 4.78 | MLS | Cometic | C5843-030 |
| 89.5 mm | 0.91 mm | 5.73 | MLS | Cometic | C5843-036 |
| 89.5 mm | 1.02 mm | 6.42 | MLS | Cometic | C5843-040 |
| 89.5 mm | 1.14 mm | 7.17 | MLS | Cometic | C5843-045 |
| 89.5 mm | 1.30 mm | 8.18 | MLS | Cometic | C5843-051 |
| 89.5 mm | 1.42 mm | 8.93 | MLS | Cometic | C5843-056 |
| 89.5 mm | 1.52 mm | 9.56 | MLS | Cometic | C5843-060 |
| 89.5 mm | 2.03 mm | 12.77 | MLS | Cometic | C5843-080 |
| 89.5 mm | 2.18 mm | 13.71 | MLS | Cometic | C5843-086 |
| 89.5 mm | 2.49 mm | 15.67 | MLS | Cometic | C5843-098 |
| 89.5 mm | 3.05 mm | 19.19 | MLS | Cometic | C5843-120 |
| 92 mm | 0.46 mm | 3.06 | MLS | Cometic | C5842-018 |
| 92 mm | 0.58 mm | 3.86 | MLS | Cometic | C5842-023 |
| 92 mm | 0.69 mm | 4.59 | MLS | Cometic | C5842-027 |
| 92 mm | 0.76 mm | 5.05 | MLS | Cometic | C5842-030 |
| 92 mm | 0.91 mm | 6.05 | MLS | Cometic | C5842-036 |
| 92 mm | 1.02 mm | 6.78 | MLS | Cometic | C5842-040 |
| 92 mm | 1.14 mm | 7.58 | MLS | Cometic | C5842-045 |
| 92 mm | 1.30 mm | 8.64 | MLS | Cometic | C5842-051 |
| 92 mm | 1.42 mm | 9.44 | MLS | Cometic | C5842-056 |
| 92 mm | 1.52 mm | 10.10 | MLS | Cometic | C5842-060 |
| 92 mm | 1.68 mm | 11.17 | MLS | Cometic | C5842-066 |
| 92 mm | 1.78 mm | 11.83 | MLS | Cometic | C5842-070 |
| 92 mm | 1.91 mm | 12.70 | MLS | Cometic | C5842-075 |
| 92 mm | 2.03 mm | 13.49 | MLS | Cometic | C5842-080 |
| 92 mm | 2.13 mm | 14.16 | MLS | Cometic | C5842-084 |
| 92 mm | 2.18 mm | 14.49 | MLS | Cometic | C5842-086 |
| 92 mm | 2.34 mm | 15.56 | MLS | Cometic | C5842-092 |
| 92 mm | 2.49 mm | 16.55 | MLS | Cometic | C5842-098 |
| 92 mm | 3.05 mm | 20.28 | MLS | Cometic | C5842-120 |
| 92 mm | 3.56 mm | 23.67 | MLS | Cometic | C5842-140 |
Gasket volume: the space the gasket leaves above each cylinder. It enlarges the combustion chamber, and the larger it is, the lower the compression ratio. Values compare with one another at identical gasket bore.
| Fasteners | Engines | Tightening torque |
| Original cylinder head bolts LF01-10-135 | LF-DE | Not published |
Before fitting, check the flatness of the cylinder head and of the block with a straight edge and have them skimmed if necessary. These gaskets require no sealant: Cometic supplies them already coated.
 | Cometic MLS Several stamped and riveted stainless steel layers. The outer layers carry active beads around each cylinder and each fluid passage. Sealing is achieved with a moderate clamping load and limited bore distortion. This is the versatile choice, from a prepared naturally aspirated engine to light forced induction. |
Gasket bore. The Cometic MLS comes in 89.5 and 92 mm.
Thickness. Mazda 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 | The value closest to the thickness of the removed gasket |
| Skimmed cylinder head, make up the lost height | The thickness of the removed gasket + what was removed |
| Forced induction build, lower the ratio | A thickness above that of the removed gasket |
| Naturally aspirated build, raise the ratio | A thickness below that of the removed gasket |
With a thickness finer than that of the removed gasket, measure piston protrusion above the block with a dial gauge: it is what determines the remaining clearance between piston and cylinder head.
 | Cometic Gasket, Inc. is an American manufacturer of engine gaskets and sealing solutions, founded in 1989 and based in Concord, Ohio. Its speciality is the made-to-order gasket, in the bore and thickness required. All its products are made in the United States, from American materials. |
| Criterion | Original gasket LF01-10-271 | Reinforced gaskets |
| Construction | Multi-layer steel (MLS) | Multi-layer stainless steel |
| Gasket bore | 89 mm | 89.5 to 92 mm |
| Thicknesses available | Not published by Mazda | 0.46 to 3.56 mm, 20 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 |
| Ford C-MAX (DM2) | AODA, AODB, AODE, SYDA | 145 hp | 2007-2010 |
| Ford Focus C-MAX (DM2) | AODA, AODB, AODE, SYDA | 145 hp | 2004-2007 |
| Ford Focus II | AODA, AODB, AODE, SYDA | 140, 141, 145 and 148 hp | 2004-2013 |
| Ford Galaxy II (WA6) | AOWA, AOWB, SEWA, TBWA, TBWB | 145 and 160 hp | 2006-2015 |
| Ford Mondeo IV (BA7) | AOBA, AOBC, SEBA, TBBA, TBBB | 145 and 160 hp | 2007-2015 |
| Ford Ranger (ET) | T23HDEX | 148 and 150 hp | 2006-2012 |
| Ford S-MAX (WA6) | AOWA, AOWB, SEWA, TBWA, TBWB | 145 and 160 hp | 2006-2014 |
| Mazda 3 (BK) | LF-DE | 141 and 150 hp | 2003-2009 |
| Mazda 5 (CR) | LF-DE | 146 hp | 2005-2010 |
| Mazda 6 (GG, GY) | LF-DE | 141, 144 and 150 hp | 2002-2008 |
| Mazda 6 (GH) | LF-DE | 155 hp | 2010-2013 |
OEM part number: LF01-10-271, L309-10-271, LF02-10-271 (Mazda LF-DE).
Important: the 2.3-litre Duratec of the Ford Fusion (C23HDEX) and the Mazda LF-VE, L3-VE and L5-VE take other cylinder head gaskets: they are not covered by this page.
A reinforced gasket holds where the standard one reaches its limit: at higher combustion pressure it keeps its shape instead of being crushed.
As soon as power goes up, turbo, supercharger or raised compression ratio, the head gasket becomes the weak link of the top end. Switching to a reinforced gasket is then not a comfort but a safeguard: it is what prevents the failure and the head removal that comes with it.
