How to check a used engine's condition?

Making sure a used engine is functioning properly requires checking it. Check for external problems such as cracks, rust, or oil leaks. Verify the color and level of the oil. Clean oil is ideal, but sludgy, black oil may indicate poor maintenance. Try manually rotating the crankshaft pulley. This aids in determining whether the engine is stalled. Additionally, look for wear or oil stains on the spark plugs. These indicators may indicate engine problems.
Inquire with the seller about the engine's history and mileage. Less-traveled engines tend to survive longer. Ask for a compression test or listen to the engine running if you can. This evaluates its effectiveness. Verify that every component, including belts and hoses, is in good condition .They shouldn't be too worn out. If you're still unsure, get a trusted mechanic to inspect it. A detailed check can prevent costly repairs later.