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The following torque figures have been gathered through work we have undertaken on all smart models. This list is not exhaustive and has been based on record information made available to us. These figures are subject to change and should be used with care.

ComponentApplicable EnginesTorque
Pistons / Crank    
Piston conrod bolts (2x per piston) All 450, 451 & 452 engines 15Nm + 90°
Piston conrod bolts (2x per piston) CDI 5Nm + 25Nm + 180°
Lower crankcase bolts (8x M8) All 450 & 452 21Nm + 90°
Lower crankcase bolts (8x M8) CDI 55Nm + 90°
Lower crankcase bolts (M6) All 450 & 452 9.5Nm
Oil Pump System    
Oil pump sprocket All 450 & 452 20Nm
Oil pump bolts (3x) - Initial Torque
Oil pump bolts (3x) - Final Torque
All 450 & 452 14Nm
9.5Nm
Oil pick up pipe bolts (3x) - Initial Torque
Oil pick up pipe bolts (3x) - Final Torque
All 450 & 452 12Nm
9.5Nm
Oil baffle bolts All 451 24Nm
Oil filter body bolts - blind hole All 450 & 452 12Nm
Oil filter body bolts - clearance hole All 450 & 452 9.5Nm
Oil filter case All 450 & 452 23Nm
Oil cooler water line to crankcase - initial torque
Oil cooler water line to crankcase - retightening torque
450 Brabus (55kW) & 452 12Nm
9.5Nm
Engine Timing    
Timing chain hydraulic tensioner bolts (2x) All 450 & 452 + 450 CDI 12Nm
Timing case oil duct bolt (1x) All 450 & 452 30Nm
Timing case bolts - Initial Torque
Timing case bolts - Final Torque
All 450 & 452 12Nm
9.5Nm
Timing case bolts M6 All 451 10Nm
Timing case bolts M8 All 451 23Nm
Bolt connecting end of crank sealing ring to crankcase All 451 10Nm
Timing case plug All 451 50Nm
Drive Plates / Pulleys    
Belt pulley bolt into crankshaft (1x) All 450 & 452 + CDI 140Nm + 90°
Bolt holding drive plate to other end of crankshaft 450 599cc engines only 47.5Nm + 90°
Bolt holding drive plate to other end of crankshaft All 698cc engines only + CDI 45Nm + 90°
Clutch Assembly    
Clutch module to drive plate bolts (3x) All 450 & 452 20Nm + 90° + 10°
Clutch pressure plate to flywheel bolts All 451 20Nm
Clutch release bearing to gearbox All 450, 451 & 452 10Nm
Clutch actuator bolts All 450, 451 & 452 10Nm
Gearbox bolts (gearbox to engine) All 450 & 452 23Nm
Gearbox bolts (gearbox to engine) All 451 45Nm
Gearbox oil drain plug All 450, 451 & 452 43Nm
Gearbox assembly bolts All 450 & 452 27Nm + release + 25Nm
Cylinder Head    
Cylinder head bolts (8x) All 450 & 452 21Nm + 90° + 90° + 10°
Cylinder head bolts (8x) CDI 30Nm + 90° + 90° + 90° + 10°
Cylinder head bolts All 451 25Nm + 90°+ 90°
Cylinder head bolt to timing cover (2x) All 450 & 452 27Nm
Sump    
Sump bolts - Initial Torque
Sump bolts - Final Torque
All 450 & 452 12Nm
9Nm
Sump bolts - Initial Torque
Sump bolts - Final Torque
All 451 10Nm
10Nm
Dipstick tube bolt (1x) - Initial Torque
Dipstick tube bolt (1x) - Final Torque
All 450 & 452 12Nm
9Nm
Sump drain plug All 451 65Nm
Camshaft    
Camshaft sprocket bolt (1x) All 450 & 452 21Nm + 90°+ 10°
Camshaft cap bolt (2x per cap) - Initial Torque
Camshaft cap bolt (2x per cap) - Final Torque
450 599cc engines only 11Nm
8.4Nm
Camshaft cap bolt (2x per cap) - Initial Torque
Camshaft cap bolt (2x per cap) - Final Torque
All 698cc engines 12Nm
12Nm
Rocker Cover    
Rocker cover bolts - Initial Torque
Rocker cover bolts - Final Torque
All 450 & 452 12Nm
9.5Nm
Rocker cover bolts All 451 10Nm
Load bleed plate to crankcase bolts All 451 10Nm
Ignition Coils    
Coil pack bolts (2x per coil pack) All 450 & 452 14Nm
Coil pack bolts (2x per coil pack) All 451 10Nm
Starter Motor    
Starter motor securing bolt All 450 & 452 23Nm
Starter motor securing bolt All 451 42Nm
Constant live connection to starter motor All 450 & 452 8Nm
Constant live connection to starter motor All 451 10Nm
Water pump system    
Water pump to carrier bolts All 450 & 452 9.5Nm
Water pump carrier to crankcase bolt All 450 & 452 20Nm
Water pump pulley to water pump All 450, 451 & 452 10Nm
Turbo water pipes banjo bolts All 450 only 19Nm
Turbo water pipes banjo bolts All 452 only 20Nm
Thermostat to cylinder head - initial torque
Thermostat to cylinder head - final torque
All 450 & 452 12Nm
9.5Nm
Water supply connection to carrier - initial torque
Water supply connection to carrier - final torque
All 450 & 452 14Nm
9.5Nm
Water pump to timing case - M6 All 451 10Nm
Water pump to timing case - M8 All 451 23Nm
Thermostat housing bolts All 451 10Nm
Coolant pipe bolts (crankcase & oiil pan) All 451 10Nm
Coolant Drain Plug All 450 & 452 12Nm
Inlets    
Fuel rail bolts (to inlet manifold - 2x) All 450 & 452 8Nm
Fuel rail bolts (to inlet manifold) All 451 9Nm
Fuel rail to air inlet pipe All 451 9Nm
Throttle body bolts (to inlet manifold) All 450, 451 & 452 9Nm
Inlet manifold bolts - Initial Torque
Inlet manifold bolts - Final Torque
All 450 & 452 12Nm
10Nm
Inlet manifold bolts - Initial Torque
Inlet manifold bolts - Final Torque
All 451 20Nm
20Nm
Turbo System    
Turbo oil pipe bolts (2x) 450 599cc engines only 7.6Nm
Turbo oil pipe bolts (2x) All 698cc engines 8Nm
Turbo oil line banjo bolt (to crankcase 1x) All 450 & 452 10Nm
Wastegate actuator securing bolts (2x) All 450 & 452 7Nm
Turbo exhaust manifold studs (7x on 599cc, 8x on 698cc) All 450 & 452 6Nm
Turbo exhaust manifold nuts (7x on 599cc, 6x on 698cc) All 450 & 452 16Nm
Combination valve line nuts on exhaust manifold (2x) All 698cc engines only 10Nm
Exhaust studs (2x) 450 599cc & 452 8.5Nm
Exhaust studs (2x) 450 698cc engines only 9Nm
Banjo bolt for exhaust line to combination valve (1x) All 698cc engines only 34Nm
Bolt for combination valve to cylinder head (1x) All 698cc engines only 12Nm
Alternator    
Alternator wiring nuts All 450 & 452 8Nm
Alternator wiring nuts All 451 10Nm
Alternator carrier bolts 599cc engines only 27.5Nm
Alternator carrier bolts 698cc engines 25Nm
Alternator bracket to crankcase bolt 599cc engines only 27Nm
Alternator bracket to crankcase bolt 698cc engines 25Nm
Alternator bracket to crankcase - M8 All 450 & 452 9.5Nm
Alternator bracket to crankcase - M6 All 450 & 452 12Nm
Alternator adjusting nut 599cc engines only 27.5Nm
Alternator adjusting nut 698cc engines 25Nm
Alternator to timing case cover bolt All 451 23Nm
Belt Drives    
Alternator belt tensioner to timing case bolt (1x) All 450 & 452 20Nm
Airconditioning belt tensioner to timing case cover (1x) All 450 (with aircon) 20Nm
Main belt tensioner to timing case cover (1x) All 451 49Nm
Airconditioning belt tensioner eccentric bolt (1x) All 450 & 452 (with aircon) 21Nm
TIK    
TIK bracket to gearbox bolts (2x) - Initial Torque
TIK bracket to gearbox bolts (2x) - Final Torque
All 450 & 452 12Nm
9Nm
Spark plugs    
Spark plugs - Initial Torque
Spark plugs - Final Torque
599cc engines only 23Nm
23m
Spark plugs - Initial Torque
Spark plugs - Final Torque
698cc engines only 28Nm
20Nm
Spark plugs - Initial Torque
Spark plugs - Final Torque
All 451 18Nm
18Nm
Sensors and Switches    
Oil pressure switch All 450 & 452 18Nm
Oil pressure switch All 451 10Nm
Lambda O2 sensors (both sensors if applicable) All 450 & 452 + CDI 50Nm
Lambda O2 sensor - upstream All 451 50Nm
Lambda O2 sensor - downstream All 451 40Nm
MAP sensor bolt (1x) All 450 & 452 6Nm
Knock sensor bolt (1x) All 450, 451 & 452 20Nm
TDC sensor bolt (1x) All 450 & 452 12Nm
TDC sensor bolt (1x) All 451 11Nm
Camshaft position sensor All 451 11Nm
Gear position sensor All 450 & 452 10Nm
Gearbox temperature sensor 599cc pre-2000 only 10Nm
Gearbox RPM sensor All 450 & 452 10Nm
ECU securing bolts All 450 & 452 + 450 CDI 2Nm
Engine Mounts    
Engine mount - cylinder head bolts - Initial Torque
Engine mount - cylinder head bolts - Retightening Torque
All 450 & 452 28Nm
23Nm
Engine mount - back of crankcase - Initial Torque
Engine mount - back of crankcase - Retightening Torque
All 450 & 452 28Nm
23Nm
Engine mount - gearbox - Initial Torque
Engine mount - gearbox - Retightening Torque
All 450 & 452 28Nm
23Nm
Engine mount to subframe bolts All 450 & 452 58Nm
Engine mount - right engine to frame All 451 56Nm
Engine mount - right engine to timing case All 451 80Nm
Engine mount - left engine to carrier All 451 56Nm
Engine mount - left engine to transmission All 451 80Nm
Torque support engine mounts All 451 115Nm
Carrier for front engine mount to transmission All 451 23Nm
Carrier for front engine mount to crankcase All 451 56Nm
Suspension System    
Front suspension arm top nut All 450, 451 & 452 45Nm
Suspension arm top spring plate nut All 450, 451 & 452 60Nm
Suspension arm C-clamp on rear of hub All 450 & 452 46Nm
Suspension arm C-clamp on rear of hub All 451 30Nm + 180°

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