1. External Examination:
* Obvious signs of damage: Look for any external leaks (oil, coolant, fuel), cracks in the block or head, or signs of overheating (warped surfaces, discoloration).
* Condition of belts and hoses: Check for fraying, damage, or slippage, as this can indicate related problems that contributed to the seizure.
* Condition of the fluids: Inspect the oil for metallic particles (indicating bearing failure), discoloration (indicating overheating or contamination), or sludge. Check the coolant for signs of oil contamination (head gasket failure).
2. Internal Examination (requires disassembly):
* Crankshaft: Check for scoring, bending, or damage to the journals (the cylindrical surfaces where bearings ride). Measure crankshaft endplay. A seized engine usually has substantial damage here.
* Connecting Rods: Inspect for bending, cracks, or wear on the big-end and small-end bearings. Check for scoring on the connecting rod journals.
* Pistons and Piston Rings: Examine for scoring, wear, cracks, or damage to the piston skirts or rings. Check the piston ring gap. Seized pistons will often show significant scoring or even breakage.
* Cylinder Walls: Inspect for scoring, scratches, or excessive wear. Measure cylinder bore diameter for wear and taper.
* Cylinder Head: Examine for warping, cracks, or damage to the valve seats or guides. Check for signs of overheating. Look for signs of head gasket failure.
* Valves: Check for bending, damage to the valve faces, or sticking.
* Bearings (Main and Rod): Inspect for seizing, pitting, scoring, or excessive wear. These are key components to check for damage as they're frequently the cause of a seizure.
3. Determining the Cause of Seizure (requires investigation and context):
* Lack of lubrication: This is a common cause. Check the oil pump, oil filter, and oil passages for blockages.
* Overheating: Look for signs of overheating on the engine components.
* Foreign object damage: Check for debris in the oil pan or other parts of the engine.
* Engine coolant contamination with oil: This indicates a head gasket failure.
* Engine oil contamination with coolant: This indicates a cracked cylinder head or block.
4. Assessing Repair Feasibility:
Based on the extent of the damage, determine if repair is economically feasible. Minor scoring might be repairable with honing and new pistons/rings. Significant damage to the crankshaft or block often makes rebuilding uneconomical.
In summary: A comprehensive inspection of a seized engine is a labor-intensive process requiring mechanical expertise and the right tools. The goal is to identify the *cause* of the seizure as much as the *extent* of the damage, to inform repair decisions or to establish a fair valuation if the engine is being bought or sold. If you lack the expertise, it's best to have a qualified mechanic perform the inspection.
