At what mileage does an engine typically require a major overhaul?

[VanIan]

Domestic vehicles generally require a major overhaul after about 100,000 kilometers, while imported vehicles typically need it after exceeding 100,000 kilometers. There are three scenarios that determine when an engine requires a major overhaul: 1. Scenario one: Severe oil consumption with blue smoke emission, but no oil leakage. Blue smoke emission can be due to two reasons—one could be aging valve stem seals, which does not require a major overhaul and can be resolved by replacing the seals; the other could be excessive clearance between pistons and cylinder walls, which necessitates a major overhaul. These two conditions can be identified using an endoscope. 2. Scenario two: Severe black smoke emission from the engine. This condition can be checked by measuring cylinder pressure using a cylinder pressure gauge. If the cylinder pressure is below the normal value, a major overhaul is required. 3. Scenario three: Abnormal engine noises. When abnormal noises are detected, they can be measured using an engine noise detector.