Engine Block Components and Wear Analysis

Engine Block Fundamentals

The engine block is the main element of the motor. It is the body or basic structure that supports all the other elements. Its main characteristic is rigidity, enabling it to resist great efforts without deformation.

Principal Features

• Rigidity or structural strength
• Wear resistance
• Ability to evacuate heat
• Resistance to corrosion

The Engine Base (Crankcase)

The base, or crankcase, is the lower block. It consists of seats upon which the crankshaft supports, which is secured to the bank by cowls with the interposition of bearing metal caps.

Cylinders and Required Properties

Cylinders are hollow, cylindrical parts built onto the block. Inside each cylinder, a piston moves in a reciprocating linear motion. The properties they must comply with include:

• Wear resistance
• Good thermal conductivity
• Good sliding qualities

Cylinder Requirements and Wear Factors

Cylinders must:

1. Be completely cylindrical and free of any ovality or taper.
2. Be free (have the same diameter throughout their length).
3. Have a smooth interior surface, free of scratches, cracks, or steps.
4. Be perpendicular to the upper surface of the block.

Factors affecting cylinder wear:

• Movement of the piston at extremely high speed.
• Use of low-quality oil, inadequate viscosity, or poorly maintained oil.
• Insufficient support of the segments.
• Cold starts, using rich mixtures and excess fuel without aeration, which dilutes and eliminates lubrication oil in that area.
• Sustained high temperatures due to poor refrigeration maintenance.
• A faulty air filter, allowing corrosive particles into the system via coolant or oil.

Alternative Wear Measurements

Ovality: Difference of diameters measured in the same plane perpendicular to the cylinder axis.

Taper: Difference of diameters measured in the same plane parallel to the cylinder axis.

Engine Failures Attributed to the Block

Failures related to the engine block include:

• Loss of coolant to the outside.
• Coolant passing into the oil.
• Oil passing into the coolant.
• Loss of oil to the exterior.
• Lack of engine performance.
• Excessive oil consumption.

Engine Block Inspection Checks

Essential checks for the engine block:

1. Clean, detailed visual inspection of the entire block.
2. Checking the contact surface for the cylinder head and gasket.
3. Checking cylinder wear.
4. Checking the status of the inner wall of the cylinder liners for scratches, cracks, or signs of seizure.
5. Checking the ovality of the sleeves or cylinder inner wall using an alexometer, making two measurements.
6. Checking the taper of the sleeves or inside wall of the cylinder using an alexometer, conducting three separate measurements of the cylinder wall.