How to Check a Used Car's Engine

Buying a pre-owned car can save you thousands of dollars, unless you make the mistake of purchasing a vehicle with mechanical problems. One of the biggest issues with buying a used car is determining engine condition. By taking the time to give the car a proper test-drive and conduct a thorough inspection of the vehicle's engine, you can help ensure you're getting an automobile that still has plenty of miles left on it.

Instructions

Inspection

1

Check the odometer. If it reads much over 100,000 miles the engine may be reaching the end of its life and you should probably move on to another vehicle, unless you are prepared to pay for a new engine.

2

Lift the hood and start the car. The engine should run smoothly, without surging or stalling. Listen for any unusual noises; loud knocking, pinging or grinding sounds that indicate excessive internal wear. The exception to this is a diesel engine, in which case a pinging-rattling sound is normal.

3

Drive the car for several miles around the city and on the highway, testing for acceleration while paying attention for vibrations that may indicate misfiring. Watch for smoke while accelerating. Blue, black or white smoke indicates a needed repair. A little black smoke at start-up is normal with a diesel engine. Check that the gauges are all operating in their normal ranges and that the "check engine" light is not coming on.

4

Park in a level spot and open the hood. Look under the vehicle for leaks. Turn the engine off and remove the engine oil dipstick. Using a rag, check that the oil is clear to light brown and at least up to the lower mark on the stick. Black oil, or carbon deposits on the stick indicate neglect. A light grayish colored froth on the stick generally indicates water is leaking into the engine from a blown gasket or warped head, probably from overheating.

5

Examine all surfaces of the engine, looking for fluid leaks. Dealers will usually steam-clean the engine, removing grease and grime. This will allow you to detect any leaks or seepage from gaskets and also to see if any areas have been recently repaired. Look for new spots of silicone gasket material that look new or out of place that can indicate a spot-repair. This can mean an expensive repair down the road if the engine needs to be disassembled to replace a gasket. Note that water condensation around the AC compressor, or on the pavement, is normal if the air conditioning has been running.

6

Remove the oil-fill cap and shine the flashlight inside. Look on the internal surfaces for think black gunk or sludge buildup. This indicates, at best, that the engine has not been serviced regularly.

7

Look for bulging gaskets, striped bolts and loose wires, all of which indicate the vehicle has not been properly maintained. Finally, timing belts need to be changed at certain intervals, depending on the manufacturer. Try to ascertain if has been changed, or if is getting close to needing a change. The belt may not be visible due to a protective cover, so ask the dealer or owner if it has been changed. If a receipt can't be produced, assume it has not been done.