Cold start can reveal many hidden problems
The best way to catch hidden engine problems is to start it cold. To do this, it might be a good idea to come to the dealer a little earlier than your appointment time. First thing that this will reveal is how good is the battery, because if the battery is old, it might need to be boosted to start the car. Another thing to look at a cold start is the engine noises. If the engine rattles or makes other loud noises, it might be excessively worn or has some mechanical problems. Similarly, a blue smoke at a start-up means the engine is worn and it’s best to look for another vehicle.
‘Check Engine’ light stays on
 After the car is started, all warning lights on the dash should come off. For example, in this car, the engine symbol that is known as “Check Engine” light remained on after it was started. This means that the engine computer detected some fault. It could be a minor issue, but it also could be a very expensive to repair problem. There is no way of knowing how serious is the problem until the car is properly diagnosed. |
Smoke from exhaust
 Here is another example: we started this car and noticed a blue-gray smoke from the exhaust. It smelled like burning oil too. A blue smoke means that the engine burns oil. Cars like this should be avoided. |
Test drive
During the test drive, watch out for engine noises, vibrations, lack of power, or any other driveability issues. When started, the engine should run smooth, without shaking or hesitation. If you feel that the engine is bucking or stumbling when accelerated, there is a problem. The idle speed should be stable too. Test drive for as long as possible; sometimes problems may not be obvious during a short drive around the block. It’s best to try the car in all modes: acceleration, deceleration, stop-and-go traffic, highway cruising. Watch out for the engine temperature on the dash. Once the engine is warmed up, the temperature gauge should stay somewhere around the middle of the scale.
Even if everything seems OK, we strongly recommend to have the used car properly inspected by an independent mechanic before buying.
