Crankshaft; Flywheel - Alfa Romeo 159 Training Material

ENGINE
FEATURES: The pistons of both engine versions have indents for valves and a dish for the combustion chamber on
the roof. The lower part is cooled by a jet of oil. The 2.2 litre engine piston has a seat on the skirt for avoiding
interference with the sprayer nozzle. The connecting rod caps are fracture-split and joined by pressure with screws
along with 1 mm thick half bronze bearings. Pistons and connecting rod small ends are connected by a bronze
bearing and a gudgeon pin held in plate by two snap rings.
The 2.2 engine connecting rods are 145.5 mm long; the 1.9 engine connecting rods are 153 mm long.
MAINTENANCE: Since connecting rod caps are fracture-split, each cap couples perfectly with its connecting rod.
When refitting connecting rod caps, make sure that each cap is coupled with its connecting rod to prevent damage
due to imperfect surface coupling.

Crankshaft

1. Crankshaft
2. Phonic wheel
3. Phonic wheel fastening screws
FUNCTION: The crankshaft transmits motion to the flywheel and therefore to the driveline by effect of the drive
torque resulting from the thrust of the gasses. It drives the other turning parts of the engine and the various
accessories.
MATERIAL: The crankshafts of both engine versions are made of cast iron.
FEATURES: The crankshaft is supported by five main bearings supported by the crankcase main bearings and eight
counterweights. The steel phonic wheel is fitted on the eighth counterweight with three screws. Along with the speed
sensor, the phonic wheel generates the crankshaft speed signal and determines top dead centre. The crankshaft
ends on one side with a flange for fastening to the flywheel and with an engine pulley on the other end. The
crankshafts of the two engine versions (1.9 and 2.2) are different.

Flywheel

The Sachs flywheel is of the damped dual-mass type.
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ALFA 159 TRAINING MATERIAL
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