When buying a used car, inspect as much of the vehicle as possible, particularly the condition of the engine. Obviously, if the engine doesn’t work, the car is worthless to most buyers. It’s important to make sure that the engine is in good running condition and won’t break down a few days or a week after you purchase the vehicle. Here’s a quick used car engine checklist to inspect a used car before you buy it.

Instant diagnosis

If you can borrow, rent, or already have a car code reader: use it! Many code readers come with phone apps that instantly tell you what diagnostic codes mean. If a code reader tells you that the car has a variety of problems from the get-go, you won’t have to waste time inspecting the rest of it. Scan ports are typically under the steering wheel. Just plug in the reader and look up the indicated codes to see what’s wrong with the vehicle.

Pop the hood

Open the hood – make sure it stays up on its own properly before getting under it – and check for anything that stands out instantly: is it clean or is there grime everywhere? Do you see obvious damage or visible leaks?

If the engine looks like it’s been cleaned vigorously compared to the rest of the vehicle – the seller may be trying to hide an issue or cover up an existing leak. Of course, gauge the condition of the engine by the overall state of the vehicle. If the car has 100,000 miles on it, the engine most likely won’t be bright and shiny. If it’s a newer car with low miles, the engine will appear in much better condition.

Look where the fenders bolt to the core support – the component in front of the radiator – and make sure they are aligned and straight. Correcting frame damage is difficult and anything that appears misaligned can indicate that the car was in an accident. Follow the core support and make sure it isn’t bowed up or down or bent in any way. If it is, that could mean the car was involved in a front-end accident and could have frame damage. Integral engine components could have been knocked loose or damaged.

Look for any obvious damage on the front bumper and side panels – if there is anything out of the ordinary, investigate! For example, if the front bumper is dented, look at the radiator to make sure it isn’t damaged, along with the frame beneath the bumper. Significant frame damage can indicate hidden mechanical issues and can impact the overall safety and drivability of the vehicle.

Look for leaks

Now take a closer look at the engine. Since leaks drip down – you may miss something if you only look at the engine from the top, so you’ll need to look underneath the car as well to look at other components. Look for remnants of fluid or anything that looks like it was recently wiped down. Pay close attention for leaks coming from the transmission or oil pan.

Look at the cooling system, but make sure the car is cold before you open the cap! Make sure the coolant is full to the proper levels and appears bright in color. Any sludge, gunk, or oil in the coolant could indicate serious engine problems, such as a blown head gasket.

Check the master brake cylinder to make sure the fluid is full too.

Check the power steering reservoir if applicable – pull the cap off and check the color of the fluid. If it’s dark or has specks in it, that can indicate issues. As with other fluids, make sure the power steering fluid is filled to the proper level. Follow the power steering lines to the pump for any obvious leaks.

Take the oil cap off and check the underside of the cap itself. If there’s a frothy substance or gunk under the cap, that can mean that the head gasket is blown. Check in the engine with a flashlight too and look for the same thing. Check the oil dipstick and make sure the oil is filled to the indicated levels, and make sure it isn’t discolored (healthy oil is typically an amber color) and doesn’t have metallic specks.

Check the transmission fluid for the same thing: it should be red and absent of specks. Brown transmission fluid could indicate problems.

Look at the hoses and belts. Make sure the hoses aren’t stiff, misshapen, or cracked. Belts shouldn’t be cracked or frayed and should maintain elasticity if you press on one with a finger.

Start the car

Now’s a good time to start the car. Make sure you’re watching the exhaust as the car starts: If blue smoke comes out, that could mean valve seals are leaking. Have somebody rev the engine while you’re observing the exhaust, as well. Again, you’re looking for blue or white smoke. Do the same check when the car is warm too.

Go back to the engine bay and have the somebody start the car while you’re looking at the engine. Make sure the engine doesn’t jolt or move too much – that could mean worn out engine mounts.

Now’s a good time to check for leaks again. Now that pressure is applied to all the components, it may be easier to spot a leak. Check the cooling system, the master brake cylinder, around the engine, all hoses, the water pump, power steering again. Take off the oil cap and make sure there isn’t strong pulsing air or smoke coming out of the engine.

Now, just listen and watch. Is the car idling at a steady rate? Do you hear loud ticking or any other irregular noises?

Test drive

Now that you’ve looked around at the engine and exhaust and nothing stands out, take the car for a test drive. When you get in and the car is running, take a look at the dash. Are any check engine, ABS, or oil lights on? When you’re on the road with it, make sure it drives straight and the alignment is good. Does applying gas cause the car to lurch? Do the brakes work smoothly? Does the transmission shift smoothly?

Last, have somebody shut the engine down while you have the hood open. Make sure the engine doesn’t jolt or vibrate heavily, or that you hear any loud knocking or other irregular noises.

Be thorough

You don’t want to get stuck with buyer’s remorse and a vehicle that’s going to cost you more than you thought it would in repairs. Make sure to look at all aspects of the car to ensure you’re buying a quality vehicle regardless of its age. Remember, if you’re buying a vehicle from AutoBidMaster.com, you can inspect the vehicle in person at the Copart yard, and we strongly suggest performing the above inspection on any potential purchase.