1. Ready for Review

WRAP UP: Ready for Review

 

  • The cylinder block is the largest single part and main structure of the diesel engine, and its primary function is to support cylinders and liners (if equipped) and major engine components, including the crankshaft and the camshaft.
  • Diesel engine blocks have cylinders arranged either in-line, V-banked, or horizontally opposed and can be configured with different numbers of cylinder bores.
  • Cylinder blocks can be constructed from cast iron, aluminum, or compacted graphite iron; each of these materials has advantages and disadvantages.
  • Primary balance, which is achieved when the crankshaft counterweights offset the weight of the piston and connecting rod assembly, and secondary balance, which is achieved when the movement of one piston counterbalances the movement of another, result in smoother-running engines.
  • The main purpose of the crankshaft in a reciprocating engine is to convert the linear motion of the connecting rod assemblies to rotational movement.
  • The mechanical stresses placed on a crankshaft require it to be especially strong, so crankshafts are hardened to improve durability; the two most common processes are induction hardening and nitriding.
  • Engine oil is used to lubricate, cool, and clean the crankshaft journals and bearings.
  • To control the destructive effects of both torsional and harmonic vibrations, diesel engines are equipped with vibration dampers.
  • Blocks must be designed to be as compact as possible to reduce weight and size while maintaining strength and rigidity; common block designs include deep-skirt blocks, cross-bolted blocks, ladder-frame blocks, and tunnel-bore blocks.
  • There are several different configurations for engine block cylinders; which one is best depends on the vehicle’s application, production cost, and expected vehicle life cycle.
  • Replaceable cylinder sleeves enable a worn-out engine to be quickly rebuilt and restored to factory specifications.
  • Bearings perform important functions inside the engine, including reducing friction, supporting moving parts under load, and serving as replaceable wear surfaces.
  • The characteristics important for engine bearings are compatibility, fatigue strength, conformability, and embedability; a variety of construction techniques are used to achieve different balances among the characteristics that will adapt to each engine’s unique operating conditions.
  • The amount of oil clearance between the rotating shaft and the engine bearing is important for maintaining the hydraulic pressure of the oil wedge that cools and lubricates these parts.
  • Bearings must not move within the bearing bore and must have good contact within the bore for proper heat transfer.
  • Thrust bearings control end play in a crankshaft.
  • The fit of a liner into the cylinder block is critical to engine operation; improper fit can produce various leaks and cause premature, if not catastrophic, damage to cylinder components, such as pistons and rings.
  • Adequate piston skirt clearance must be maintained between the liner and the piston to allow for normal expansion of the piston when the engine is running at operating temperature.
  • Wet liners protrude or extend above the cylinder block deck to project clamping forces from the cylinder head onto the liner flange and hold it in place; measuring and adjusting protrusion is one of the most critical operations when rebuilding a sleeved engine.
  • Top-stop flange breakage is usually caused by excessive flange loading because of significant pressure that was applied to the flange through the cylinder head clamping forces.
  • Cylinder block walls progressively wear with increasing engine hours and distance traveled; a dial bore gauge is used to measure cylinder wear resulting from taper.

 

©2026 - CDX