How to check a used car's engine (with pictures)

You should always consider, no matter how much you like it at first glance, that no one sells a car because it runs too well, or because it is too cheap to maintain. However "used" does not necessarily mean bad, as even older cars can work perfectly if they have been well cared for. You should use your head before spending your money to ensure that you are not making a purchase that you will immediately regret. The first thing is to check the engine.

Steps

Part 1 of 3: Getting Started

Step 1. Look for spots, drips, or puddles under the car

Before even looking inside the car, you should kneel down and look under it for stains, drips, or puddles. If you find any, try to find out, are they old traces or a recent stain? Is there a drip that is forming a small puddle?

• Evaluate and decide if the car is accidentally parked on an oil slick or if it is leaking fluids right in front of your eyes. While it's not always a reason to cancel the deal, any drips, leaks, or leaks can indicate much bigger problems.

  

• Sellers or car owners will say that it is normal for a little oil to drip and this is relatively true - some car models are notorious for this and it does not mean the car is in trouble. It is up to you if you think it is worth adding oil every so often.

  

Step 2. Identify the type of fluid that forms the puddles

Puddles can form from brake fluid, coolant, transmission, power steering, or even windshield washer fluid. If you find one you may want to touch it to find out what it is.

• A reddish fluid could be from the transmission. A black fluid is generally just oil. A caramel color could be lightly used oil, old power steering, or brake fluid. A green or orange liquid is probably refrigerant.
• Consider light-colored puddles that may be water, either because it has rained, the engine has been washed, or the air conditioner has been on recently. Once you touch it, you will be able to tell if it is something made of water or oil. If it looks like both, be careful and pay attention to the next steps.

Step 3. Inspect the chassis

Sellers often wash a car they want to sell, some will even try to clean the engine compartment, but as a rule they will overlook the underside of the car. See how clean it is even if there are no puddles. Expect to see dirt, mud, and grease spots (this is a car after all) but watch out for drips or drops of fluid that have formed and haven't fallen off.

• Pay attention to the oil pan especially, dark spots and lumps of oily sludge, and any joints or cracks you see. It is common to find some dirt left over from old problems that have already been repaired.
• However, fresh dirt or oil can spell trouble, so take note. Feel free to touch what you see (perhaps with a paper towel) to see how much it leaks, if it's wet, if it's slippery, or what it's covered in.

Step 4. Decide if leaks are a problem for you

If you see a drip or traces of wet mud, try to determine where it is coming from. Leaks may be enough for you to decide to evaluate the next car, but it will be up to you to decide if leaks themselves are a problem that will prevent you from buying that car.

• Some like to constantly add oil to their cars to compensate for a leaking oil pan, and these can go years without problems beyond the expense. Some leaks are small and can take months to generate any significant loss, but others get worse over time and can lead to serious problems.
• If there are no obvious leaks or leaks and you can't find anything covered in mud, you're ready to relax. Many potential engine problems can be ruled out as there are no visible fluid leaks.

Part 2 of 3: Inspecting the engine

Step 1. Open the hood and smell the odors coming from the engine

Before starting the engine, have the dealer open the hood to look at it and notice any odors.

• A new engine should smell like rubber and plastic with a hint of oil or gasoline. In the best conditions you will smell the vapors that come naturally from the belts, hoses and plastic parts. This is known as fumes and they are completely normal. The smell of a new engine compartment should not be much different than the smell of new tires.
• In a used car you will smell oil, in most cases. This is normal, and as long as it is not overwhelming there is nothing to worry about. You could also smell fuel. A subtle smell of fuel is perfectly normal, even a strong burst of gasoline smell is common in vintage cars with carburettors. However, if you smell a lot of fuel this can mean a leak in the distribution system and be a cause for concern.
• You may also smell a "turpentine" smell, which is essentially the smell of old gasoline. That smell indicates that the car has been idle for a while. Ask the seller if there is fresh fuel in the tank and how long the car has been parked. This is not usually an inconvenience, but stagnant fuel can cause a number of problems, such as rusting the fuel tank.
• Another possibility is the slightly sweet aroma of the antifreeze. This may be from a spill, but you should still check the cooling system for leaks. On a cold engine you may notice a whitish or greenish film, a sign that the coolant has evaporated. There may also be a pungent odor which means the battery will need to be checked.

Step 2. Carefully inspect the engine compartment and its contents

Check the engine. See paint, bare metal, grime, or dirt? Keep in mind that it is preferable to see dirt or even spider webs. Sellers often clean the engine compartment to be courteous and to keep it looking good. This makes the engine look better, but it can remove evidence of leaks and even prevent you from seeing obvious faults.

• A dirt-covered engine, on the other hand, will show you where every drop of oil is, which parts have been tampered with or replaced, and it also indicates that the car has been driven, meaning at least it has run recently. Spider webs indicate that it has been idle for a while, which may mean nothing, or it may mean extra steps later.
• An engine covered in mud and grime is both good and bad. It may indicate a leak, but you can at least indicate the source by following the path of the mud. If it's just a bunch of mud it may be time to change or even rebuild the packings.
• However, this does not mean that the engine itself has gone bad, or that you will not be able to drive it for years before you have any serious problems. A fuel leak will often create a clean area on a dirty engine, but fuel leaks are usually subtle and you'll need your nose to check for any.

Step 3. Check the fluid level

By now you should know the oil gauge. Remove it, clean it, reattach it, and remove it again. Is there oil? Well. There may be little oil, as long as there is some. Most cars will not show the correct oil level until they have warmed up.

• If you have an automatic transmission there will be another meter that you should also check using the same method. Again, we just want to make sure there is some transmission fluid in there.

  

• If you have power steering there will be a pump somewhere. Usually this pump has a cap with a small gauge. Check that there is some fluid. As you do this, check for brake fluid. Usually the reservoir of brake fluid is transparent and allows you to see how much is left unopened.

  

• Finally you should check the coolant and windshield wiper levels. Take note of any fluid that is low and remember to fill it to its proper level if you end up buying the car.

  

Step 4. Inspect the belts and hoses

Ask the seller when the belts and hoses were last changed. Cracks in the rubber usually mean that part will have to be replaced soon. Even old girdles and hoses can look good on the surface with a clever wash, so don't be afraid to squeeze the hoses and touch the girdles.

• If the hoses are of poor quality they will have to be replaced. Most distributors make sure to cover these things, but you might not be dealing with a distributor and these things are sometimes overlooked.
• Mainly you must make sure that the girdles are in place. Some cars won't start without them, but some have secondary belts that run the chargers, air conditioning, or power steering so make sure each pulley has a belt attached to it or a good reason not to.
• Check to see if the hoses are soft or mushy, which is a clearer indicator of their age than their appearance. Check the places where the hoses are attached to other things and look for a film that reveals if there are recent leaks. These leaky spots sometimes only appear when the engine is warm, so there won't be any leaks. A good dose of engine cleaner can make them disappear, so you have to see if there is even a small trace of residue that is similar to the scale that remains on the bottom of kettles.

Step 5. Inspect the battery and its terminals

Like motors, batteries can be very clean and not work the way they should. It's common for cars to drain their batteries while they're not running, so don't worry if the car needs help starting.

• For now, check the battery to be sure there are no cracks or leaks. Look for exposed wires, which isn't terrible as long as they haven't turned green or covered in a white residue.

  

• Look for a cover of white residue (or green or a combination of both) on the terminals. This is usually a sign of an old battery that has not been used in a while and can be cleaned with a brush and soda.
• You will most likely find a layer of dirt and dust or clean metal and plastic. This does not mean that the battery is working or that the terminals are not corroded in an invisible way, but it does mean that those potential problems have not been hidden by the seller.

  

Step 6. Ask about the air filters

If you buy the car from a dealer, the air filter must be new and clean. If you buy it from someone else it may be old and need to be replaced.

• If the air filter needs to be replaced, other filters (such as fuel, oil, or transmission) will likely need to be changed as well.
• Ask the seller, if you are not sure or do not want to look at the air filter yourself.

Step 7. Make sure the turbocharger is connected and free of rust

You probably won't be able to tell if the car has a turbocharger until it's running, but you can at least check for leaks, plug-in, and rust-free.

Step 8. Take a step back and look at the engine compartment as a whole

Take a broad look at the magazine and its contents. Each model has a different layout - there may be a lot going on or it may be something simple and straightforward.

• Look for loose cables and hoses. Look for the little things that seem strange to you even if you don't understand them, such as uncovered holes or possible missing pieces.
• Newer cars are harder to understand because of their electronic parts (look for obvious burns and damage) and vacuum systems.
• Older cars are simpler and forgiving of manipulations. Ask about any changes or modifications that the seller has made.

Part 3 of 3: Doing the Final Reviews

Step 1. Look under the hood of the car

Stop and take a closer look under the hood of the car. If you don't find indicators, at least you will find clues. What you want to see is a clean (dirt is not a problem) and intact coating, which is there to dampen engine noise and also to act as a fire retardant.

• A car that is leaking or burning oil may have blackened the coating. If the underside of the hood is just darkened, that's fine, but if any part is burned, broken, or removed, it's a sign of an engine fire.

  

• If you find evidence of a fire ask how it happened, as it could be a rebuilt engine in which case you should be concerned about fuel or oil leaks.
• A previous fire should worry you, but even that kind of antecedent doesn't by itself mean the car is useless.

Step 2. Examine the exhaust pipe

Exhaust leaks are one of the things that can cause engine fires. You may not be able to see the exhaust manifold well in the engine compartment, but the exhaust pipe is easy to check. The exhaust tip should be ash gray on the inside.

• If it is black on the inside it means there is too much fuel in the air mixture, which is bad but not terrible and usually means poor fuel economy. White tips indicate that there is too much air in the mixture with the fuel indicating increased wear and that the engine has been running at high temperatures.

  

• In older cars this is a valve timing and adjustment problem. In newer cars it indicates that there is something wrong with the electronics; possibly an oxygen or air flow sensor is sending inaccurate information to the computer causing errors in the regulation of the mixture. Either way, problems with the exhaust require some fine tuning.

  

Step 3. Test the car to see if it starts

After having verified all of the above, it only remains to start the car and see if it works. Three things could happen.

• Power on and off on the first try.
• It takes a minute to boot.
• Does not start.

Step 4. Find out why the car won't start

Did you turn the key and nothing happened? Doesn't the dash even turn on? Check the battery and connections. Pay attention to the terminals and make sure the wires are well connected and not corroded. A little soda will help keep them clean enough to make contact.

• Dashboard lights come on, you turn the key and hear a click and it won't start? The battery is probably dead, or not properly connected. Check it out and upload it. Remove it if necessary or use jumper cables. It is best to remove the battery, connect a charger that works with electrical current and give it some time.

  

• Engine runs but won't start? Step on the gas, wait a few seconds and try again. Step on the gas as you turn it on. If this doesn't work, try again a couple of times. If the car has been idle it may take a little time for the fuel to pass from the tank to the engine. Hopefully it will work at some point and you won't have to do it again.

  

Step 5. Check the spark plug wires

If it still won't start make sure the spark plug wires are tight. If you find any loose adjust it and try to start the car.

• Nothing yet? You will probably need to remove the spark plugs and clean them. If your car uses a carburetor, you can try pouring a few teaspoons of fuel directly into the Venturi tube (the part where the air enters).
• Sometimes this process has to be repeated to start the engine of a car that has been idle for a long time. So if you have a car that you want to sell, turn it on every now and then so this doesn't happen.

Step 6. Listen to the sound of the engine once it starts

Once you've started the engine, get out of the car and let it idle while you check the engine compartment again. Look for leaks or smoke, listen and check for any clicks, screeches, or knocks. Sniff for fuel vapors, or combustion. Here are some examples of what you might hear and suggestions of what they might mean:

• A "tictictictic" that is faster when you rev the engine. Glued lifters, flat cams, loose valves, or even a loose girdle. If it goes away when you add oil, or after you warm up the engine, the problem is with the lifter. While it is nothing to worry about, it is a problem that you will have to solve in the future.
• A "noknoknoknok" that increases in frequency when the engine is revved is called an engine knock. This may be a sign that you should not buy this car (unless it is a diesel car, because that is exactly what they sound like).
• A screech, screech, or squawk? Usually it is a belt or the pulleys that activate. If the sound continues after changing the belt, you will have to find out which pulley causes it. Alternators and air conditioning pumps can make these noises and junk sounds too. Be aware of sounds, but unless they really bother you, don't worry too much.
• A harder hit that does not match the revs when accelerating may indicate that the engine or transmission base needs to be changed. It is not an emergency but it must be repaired at some point.

Step 7. Test the car

Everything is alright? Close the hood, and if you are going to test the car take it to a nearby auto parts store to have them plug in and check other things you may not have noticed. This only applies to cars made in the eighties or later and usually helps if the "check engine" light is on.

• Your mechanic or spare parts dealer can help you from here. You've done everything you need to to make sure the engine is good enough to get to the shop. While driving, take note of any problems like lack of power or any strange movements or behavior.
• Code reading can give you details to start replacing the parts and electronics that require it to tune up the car. Your local auto parts store has a device that checks the car's computer codes and will not charge you to do so. If they try to charge you, find another store.
• You may need a tune-up, or even a rebuild. If you got to this point, you have a working engine. Congratulations. Fill up the fluids, charge the battery, put gas on it and you're already driving. See how it feels - in the end, that's what's important.

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