engine

Importance of checking engine on a used car:

     Engine is the key component inside the car that make the car move. It's rather complex and has many components to it. Most engines nowadays have computers built into them to allow them to diagnose any problems themselves. Generally if you don't see check engine light, the engine's overall condition is normal, however, it's still important to understand how to evaluate it for yourself.

How to check the engine:

     Checking the engine begins before you start the car. Open the hood and look around the engine bay for any oil leaks. Look carefully, because the more carefully you look, the better chance you have of spotting potential leaks. After you inspect for leaks, start up the car. The car should start up from 3-4 cranks without any sputtering or hesitation. Let the engine idle for about 5 minutes as you listen to how it sounds like. Closely listen for any pinging or banging noises as this might indicate engine wear. Rev the engine up and down a few times and listen for any sputtering, pinging or other suspicious noises. The engine should rev up smoothly and rev down just as smoothly without excessive vibration.

     Take the car out for a test drive. It's better to open the windows so that you can hear how the engine sounds. Drive around and floor the accelerator a few times. Acceleration should be smooth and consistent, without any jerkiness or excessive shakiness or pinging sounds. Engines are very complex to easily diagnose by sound, however generally the engine should idle and rev smoothly and consistently.

     After coming back from the test drive, open the hood and smell the engine bay. Do you smell strong oil smell? If so, there are potentially active leaks and it's better to avoid the car altogether. Shut the engine off and check engine oil. If it looks like milkshake (as opposed to light to dark brown), then the car has blown head gasket and you should avoid it. 

     Rev the engine up and look at the exhaust. Any smoking? Blue smoke indicates leaking gaskets within the engine and indicate coolant leaks. Black smoke indicates oil burn and is a sign of excessive engine wear. Some white steam might come out when the car is cold or when it's humid out, that's normal. Steam is merely condensation and isn't a problem. Steam is light white color and doesn't smell like rotten eggs or burnt oil.

Conclusion:

     The car shouldn't have any excessive vibrations produced by the engine. The engine shouldn't ping or knock, excessively vibrate or sputter under any load (unless you mismatch gears on manual transmission). It shouldn't smoke blue-ish or dark smoke and it should rev up and down smoothly, consistently and predictably. if these conditions aren't met, it's much safer to consider buying a different car.