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BMW M57 Engine Mechanical

Mechanical build detail for the BMW M57 diesel — cylinder block, cylinder head, crankshaft, connecting rods, pistons, valvetrain and timing-chain drive, including M57TU revisions.

Engine block / crankcase

Role: Central component; houses crankshaft, connecting rods and pistons
Main bearing caps: Cracked bearing caps
Bearing-cap fixing: V-engine-compliant threaded connection of main bearing caps with additional support brackets
Cylinder spacing: 91 mm
Crankcase height (crankshaft centre to cylinder-head sealing surface): 225.0 mm
Crankcase height (overall): 285.0 mm
Bore: 84.0 mm — Bore unchanged 84.0 mm across M57 and M57TU; TU displacement increase came only from stroke
Block material (M57TU): grey cast iron GG25+ — Re-engineered for higher output/torque; strength increased at thrust bearing; weight reduced 5.5 kg (10%). Cast iron NOT aluminium - the weight-optimised crankcase is a lighter iron casting, not an alloy block
Bearing-cap bolts (M57TU): Crankshaft bearing-cap bolts uprated (higher strength) for increased output
Gearbox flange (M57TU): Gearbox flange adapted to automatic gearbox 6HP26
Engine-mount bolts (M57TU): Engine-mounting-bracket bolts changed to M10 (M57 = M8)
Injection-pump flange (M57TU): Injection-pump flange geometry changed to accept new common-rail pump
Engine weight (pre-TU): 222 kg
Engine weight (M57TU): 213 kg — -9 kg vs pre-TU

Cylinder head, cover, timing/rear covers

Construction: Cast aluminium, cast timing case
Coolant flow: Coolant flow from exhaust to inlet side
Injector arrangement: Central, vertical upright arrangement of common-rail fuel injector
Valve arrangement: 4-valve arrangement (as on M47)
Exhaust ports: Exhaust ports combined in cylinder head (as on M47)
Head-bolt access: Cylinder-head bolts not accessible with camshafts mounted in position
Glow plugs: Glow plugs (heater plugs) arranged on inlet side
Oil galleries: Leak-proof arrangement of oil galleries/holes (e.g. for hydraulic valve lash adjusters)
Coolant outlet: Coolant outlet central, between cylinders 3 and 4
Inlet port: Inlet port: 1 swirl / 1 tangential port, adapted to common-rail
Head cover: Cylinder head cover combines oil separator and intake silencer in the intake-module system; mounted on cylinder head by decoupling elements
Head-cover material: Cylinder head cover material: plastic
Oil separator: Oil separator integrated; preliminary separation with cyclone, fine separation with threaded winding downstream
Timing-case cover: Timing case cover covers the chain drive in the crankcase area; aluminium die casting; sheet-metal beaded gasket (replace gasket after disassembly); unit and belt-tensioner connection on cover
Inlet port (M57TU): Intake-port geometry (swirl / tangential port) optimised for better mixture control and combustion
Timing case (M57TU): Timing-case geometry changed due to modified chain-drive ratio (new CR pump); cylinder-head cover shape adapted accordingly

Cylinder head gasket

Type: Multi-layer steel gasket
Water-flow cross-sections: Water-flow cross-sections adapted (cylinder-specific) for uniform coolant flow
Thickness grades: 3 different gasket thicknesses, selected by determined piston clearance
Thickness measurement: Gasket thickness selected from measured piston clearance x, taken at the measurement position relative to the engine longitudinal axis; reference dimension marked across bottom of measuring schematic is 36 (Fig. 14)
Gasket selection threshold: 1-hole gasket: x <= 0.92 mm
Gasket selection threshold: 2-hole gasket: 0.92 mm < x <= 1.03 mm
Gasket selection threshold: 3-hole gasket: 1.03 mm < x

Valve gear (camshafts, rocker arms, valves, springs, vacuum-pump drive)

Components: Valve gear consists of camshafts, rocker arms, valves and springs
Camshaft: Camshaft: chilled cast iron; new inlet and exhaust camshafts
Negative cam radius: Negative cam radius >= 67 mm
Rocker arms: Roller-type rocker arm, one hydraulic valve lash adjuster per valve (common part with M47); mounted on valve lash adjuster with oil supply
Valves & springs: Valves and springs: common part with M47; inlet and exhaust valves identical; bottom valve plate with integrated valve stem seal
Vacuum-pump drive: Vacuum pump driven by front of exhaust camshaft
Inlet valve V-angle: 3.75 degrees
Exhaust valve V-angle: 3.0 degrees
Valve diameter: 25.9 mm
Valve seat angle: 45 degrees
Valve stem diameter: 6 mm
Valves per cylinder: 4
Cam drive (M57TU): Exhaust camshaft now driven by a spur-gear train off the intake camshaft (as M47TU); chain drive itself is a common part with M47D20TU
Vacuum pump (M57TU): High-power vacuum pump - Pierburg single-vane pump (principle as N42)

Crankshaft (with sensor)

Role: Converts linear piston stroke into rotary motion
Front-end fixing: Threaded connection on front end designed as 4-hole mounting (replaces central bolt)
Thrust bearing: Thrust bearing designed as a constructed bearing
Material: Material: C38 mod.
Bearing surfaces: Bearing surfaces and radii inductively hardened; main bearings as on M47
Thrust-bearing location: Thrust bearing located between cylinders 5 and 6
RPM sensor: RPM signal taken from last crankshaft web; incremental wheel screwed on crankshaft web (rear)
Stroke (pre-TU): 88.0 mm
Stroke (M57TU): 90.0 mm — Crankshaft stroke extended 88 -> 90 mm; source of the TU displacement increase
Crank sensor (M57TU): Crankshaft sensor (KWG) now CSWS (Common Seal With Sensor) at the rear crankshaft end cover, adopted from M47TU; crank seal also in the rear end cover

Connecting rods (with bearings)

Big-end bearing: Big-end bearing half on conrod end designed as a sputter bearing
Material: Material: C40 mod.
Construction: Cracked version; common part with M47
Distance between hole centres (gauge length, pre-TU): 135 mm
Piston pin (gudgeon pin) diameter: 30.0 mm
Cracked connecting rods: 48 mm
Conrod gauge length (M57TU): 136 mm — Lengthened 135 -> 136 mm; thicker stem due to increased ignition pressure

Pistons (with rings and pins)

Type: Cooling-duct piston with rotationally symmetrical piston-crown bowl specific to DI common rail
Crown bowl: The lobe in the piston-crown bowl is higher than on the M47
Bowl geometry (M57TU): Modified bowl geometry (common part with M47TU), designed for the changed injection pressure
Pin bearings (M57TU): Press-fitted brass sleeves in the piston-pin bearings for higher load capacity

Chain drive

Role: Transfers crankshaft rotation to the camshafts
Configuration: 2-piece chain drive
Tensioning rail: Tensioning rail made from aluminium die casting with plastic slide lining
Chain type: Bushed roller chains
Chain drive 1: Chain drive 1: crankshaft -> common-rail high-pressure pump
Chain drive 2: Chain drive 2: high-pressure pump -> camshafts
Tensioner: Double-acting chain tensioner
Cam drive (M57TU): Chain drive is a common part with M47D20TU; exhaust camshaft driven by spur-gear train off intake camshaft (chain no longer drives cam-to-cam)

Flywheel

Role: Located between engine and gearbox; increases rotating mass for more uniform rotary motion. Type depends on gearbox fitted
Manual gearbox: Manual gearbox: dual-mass flywheel
Automatic gearbox: Automatic gearbox: sheet-metal flywheel, sandwich design

Torsional vibration damper

Type: Adaptive (engine-specific) vibration damper with a decoupled belt pulley
Design: Dual damper, adapted specifically to engine type; 3 variants (integrated pulley for ancillary-component drive) — M57 in E38/E39
Mounting: 4 central bolts tightening torque: 45 Nm
Part number - E39 manual gearbox (S5D 390Z): 2 247 886.1
Part number - E39 automatic gearbox (GM-5): 2 247 890.9
Part number - E38 automatic gearbox (5HP-24): 2 248 520.9
Viscous damper (M57TU): New crankshaft vibration damper (viscous damper): two sheet-steel housing halves; centrifugal mass floats in viscous oil, guided by friction bearings; belt pulley isolated from crank by a rubber track (decoupling belt drive from crank vibration)