How to check the engine when buying a used car
When buying a used car, the condition of the engine is very important because engine problems are expensive to repair. It's difficult to evaluate the mechanical condition of the engine during a quick test drive, that is why we recommend having a used car properly inspected by a qualified mechanic before signing the contract. Here are a few tips on how to spot signs of engine problems or lack of maintenance when checking a used car.
Checking an engine in a used car
It's difficult to evaluate the mechanical condition of the engine during a quick test drive, that is why we recommend having a used car properly inspected by a qualified mechanic before signing the contract. Here are a few tips on how to spot signs of engine problems or lack of maintenance when checking a used car.
Check service records
Service records are not always available, but it helps if the dealer or a person selling the car can produce some proof that the vehicle has been maintained regularly. If you can get access to the service records, look for oil changes and mileage records. It's a plus if you can verify that oil changes were done regularly. Depending on a manufacturer, recommended oil change intervals vary from 3,750 to 10,000 miles. If the vehicle has been driven between oil changes for much longer, the engine might be worn inside. It's also good to know whether a timing belt (if the car has one) has been changed, or what other maintenance has been done.
Have a look under the hood
Before checking under the hood, make sure, the engine is OFF, the transmission is in "Park" and the parking brake is applied. What you are looking for are the leaks, smell of burnt oil or antifreeze, signs poor quality repairs or lack of maintenance, as well as 'racing' modifications. Dealers often shampoo the engine bay before showing a used car to potential buyers. This means if everything looks clean and shiny, it doesn't mean that the engine is in good shape. Let's see some examples:
Burnt oil smell under the hood
Visible oil leaks
Coolant and other leaks
This car runs fine, but there is this coolant leak from the radiator. As a minimum, this car requires a new radiator, but sometimes, a cracked radiator may be a sign of more serious problems. It's best to avoid used cars with this type of issues.
Low oil level, dirty oil
With the engine off, check under the oil cap
Watch out for performance mods
Does the engine have a timing belt?
Not all cars have a timing belt, some cars have a timing chain instead. In most cars, a timing belt needs to be replaced between 60K and 105K miles. The price to replace a timing belt ranges between $200-$450 in a 4-cylinder engine and $550-$760 in a V6. If the car you want to buy has a timing belt, it's good to know if it has been changed. Some mechanics place a sticker on the engine when a timing belt is replaced. You cannot see a timing belt under the hood, it is hidden under covers. To check its condition, your mechanic will need to remove one or two covers, and it's not always easy. A more realistic option is to check the service records to see if a timing belt has been replaced. Read more about a timing belt.
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. You will also know if the battery is good, because if the battery is old, it might need to be boosted to start the car. Watch out for engine noises and smoke when the engine is first started. If the engine rattles or makes other loud noises, or there is a blue smoke from the exhaust, look for another vehicle. This car in the photo, for example, showed a blue-gray smoke from the exhaust. It smelled like a burning oil too. A blue smoke means that the engine burns oil.
After the car is started, all warning lights on the dash should come off. If the engine symbol (Check Engine) light or Service Engine Soon stays on, the engine computer detected some fault.
It could be a minor issue, but it also could be a very expensive problem. There is no way of knowing how serious is the problem until the car is properly diagnosed. Read more what "Check Engine" light means.
During the test drive, watch out for engine noises, vibration, 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 hesitating or stumbling when accelerated, there is a problem. The idle speed should be stable too. Test drive the vehicle for as long as possible; sometimes problems may not be obvious during a short drive around the block. It helps if you can test drive 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 having the used car properly inspected by an independent mechanic before buying.
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