Diagnose a Car Problem Online

woman on laptop in car

With the right information, you may be able to diagnose car trouble before taking your vehicle to a mechanic. The information you learn online about your car problem can make you a better consumer and save you money at the auto repair shop. What's more, if the problem is fairly simple, you may even be able to solve it yourself.

Common Problem: Loud Screeching or Grinding Noise

worn and new brakes

Whenever you come to an intersection and press on the brakes, do the wheels make an ear-piercing scraping sound? That sound is actually a good thing.

The Culprit: Worn Brake Pads

All brakes have a built-in warning indicator in the form of a "noise-maker" that emits this metal-on-metal scraping sound whenever the brakes are wearing down too far. The point where the brakes start emitting this noise is just above the limit when your brake calipers will start damaging the rotor of your wheel.

If you attempt to brake and you notice that there's a low rumbling or grinding noise coming from your wheels, you should try to take your car to the nearest auto mechanic as soon as possible. Don't continue using the car. This sound indicates that you've worn down the brake pads to the point where they are gone, and you have metal on metal contact between the brake caliper and the rotors.

What to Do

Never wait when you hear the brakes screeching. The longer you use your car like this, the deeper you're scraping a groove into your rotor. This will need to be machined, or your rotor will need to be replaced entirely. Take it in to a repair shop immediately, and let them know that you suspect you might need a brake job.

Common Problem: Loud Exhaust

Does your car sound like a sports car every time you accelerate? If so, you may be experiencing issues with your exhaust system.

The Culprit: Exhaust System or Muffler

Any leak of the muffler or exhaust pipe results in the engine noise escaping out of the exhaust system before the "muffler" has had a chance to do its job at silencing the engine noise. The fact that your engine sounds louder when you accelerate not only implies that you have a noise leak, but you could also have an exhaust leak, which could lead to elevated levels of carbon monoxide inside your vehicle.

What to Do

Get your exhaust system checked out immediately. This leak could be dangerous, and you could receive a ticket for a noise violation.

Common Problem: Engine Temperature Rises After Running

car overheating

If you're experiencing any situation where the temperature gauge drifts to the upper end of the scale, your car is overheating. You may or may not notice an indicator light on your dashboard.

The Culprit: Loss of Coolant

This kind of overheating is usually caused by leaking coolant from a hose or a seal. The coolant helps keep your engine from overheating due to the friction of the pistons and cylinders moving against each other. If there isn't enough coolant or it isn't getting to the engine, things can get pretty hot.

What to Do

Stop driving immediately. Driving a car with an overheated cooling system or overheated oil will quickly lead to a seized engine. This is when the friction between the pistons and the cylinders causes your engine to overheat so much that the engine completely breaks down and will require a complete rebuild to get it running again. Try to get it into a repair shop as soon as possible, and tow it in if you have to. A simple hose replacement could be all you need to save your engine from total breakdown.

Common Problem: Engine Erratically Loses Power

A common scenario, especially for people that have owned their vehicle beyond 30,000 miles, is that the engine suddenly starts sputtering or behaving erratically. This may happen at certain speeds or all the time.

The Culprit: Ignition System Breaking Down

The most common cause of this is a simple breakdown of the ignition system. The ignition system involves the spark plugs, the plug wires, and sometimes even a distributor or fuel injection system. To check the plug wires with very little effort, just bring the car into a very dark area and run the engine. If there are any cracks in the old plug wires, you'll see very faint sparks in the dark.

What to Do

Regardless the cause, if the engine is losing power, you should ask your mechanic to take a look at the plugs and wires because your engine may be due for a tune-up. People are usually very surprised how much a simple tune-up can add power that they didn't even realize the engine lost since it was new.

Use Your Senses to Diagnose Car Trouble

woman looking at car

If your problem doesn't seem to fit any of these common issues, you may still be able to diagnose it. Every day, we use our senses to form opinions about the world. If we smell smoke in the kitchen, we can assume that the cookies may be burning. If we hear a loud thumping noise from the laundry room, we know the washer is probably off balance. You can use those same skills to get an idea about what's going on with your car.

Seeing Things?

One of the easiest ways to diagnose a car problem is to use your sense of sight. Watch for smoke coming from your tailpipe or hood, and keep an eye out for puddles under your car. Your sense of sight might help you identify the following problems:

  • White smoke from the tailpipe can indicate water or antifreeze in the engine cylinder, meaning you have a failed head gasket.
  • If black smoke is coming out the tailpipe, it could indicate a problem with the fuel injection system, the fuel pump, the engine computer, or the carburetor.
  • Blue smoke coming out the tailpipe may mean a failing gasket, O-ring, or seal.
  • White smoke from under the car's hood can mean a leaky water pump or radiator.
  • Black smoke from under the car's hood can indicate burning oil, which may mean a leaking gasket.
  • A puddle of bright green, slippery fluid can mean a radiator leak.
  • A brown oily puddle under your car may indicate an engine oil leak or a lubrication leak.
  • A pool of red fluid under your car can mean you have a transmission or steering fluid leak.
  • A clear puddle may be water from your air conditioner or a power steering fluid leak.
  • Blue fluid usually means a leak in the windshield washer system.

Strange Smells

Are you noticing a strange odor in your car? Once you've eliminated the usual suspects of old sippy cups and gym bags, it's time to start using your nose to narrow down the problem. Since the smell of your car can indicate a problem, it's important to make a note of any strange odors and mention them to your mechanic. Here are some common car smells that may mean problems for your vehicle:

  • A sweet smell like pancake syrup can indicate a coolant leak or a problem with your heater.
  • An oily smell usually indicates a major oil or lubrication leak, and it's often accompanied by smoke.
  • A sulfur odor can mean a gear lubrication leak and indicate a problem with your transmission or transfer housing. It can also be a sign of catalytic converter issues.
  • A gasoline smell can indicate a leak in the fuel system.
  • A burning smell can indicate a lot of things, but some common culprits are a worn clutch or overheating brake pads.

Scary Sounds

If your car is making a strange sound, it may be trying to tell you something. Any difference in the sound of your car can indicate some kind of problem. Here are some of the most common car sounds:

  • A loud squealing can indicate a loose belt.
  • A clunking sound can indicate a problem with your car's universal or CV joint.
  • A thumping or clanking accompanied by steering problems can mean worn ball-joints or tire-rods.
  • A clicking sound that increases with speed may mean a pebble or stick that is caught in your tire or wheel well.

Vibrations and Wiggling

If driving your car just feels different, it may indicate a problem. You know how your car usually feels, and any change, especially if it's an increased vibration, can mean something is wrong. Pay attention to when and where you feel the wobbling. Here are some common problems involving vibration:

  • A wiggly steering wheel can mean uneven tire wear, a bent wheel, a missing tire balance, or a loose wheel.
  • A vibration in the pedals of the car can indicate a problem with the CV joint on a front-wheel drive car or the universal joint on a rear-wheel drive car.
  • A vibration that gets worse at higher engine speeds can mean a problem with your spark plugs, fuel injector, or engine valves.
  • A vibrating brake pedal can indicate a brake drum that is warped.
  • A general loud vibration that increases with speed can mean a problem with your wheel bearings.

More Sources to Diagnose a Car Problem Online

In addition to the above tips for diagnosing a car problem, you can find advice specific to your year, make, and model of car. The following sources may be able to help:


10w40 lists many repair complaints and questions like "car engine won't start." Scroll to find the one that meets your needs and click on it to receive free advice. This site is totally free to search and includes everything from air-conditioning to steering problems.

Just Answer

Just Answer lets you enter any topic along with the type of car you have. If you're new to the site, you'll be asked to create a user name and password. This is not a free question website. If you ask an auto repair question, you must also include a price you'll be willing to pay to receive that answer. Once you pay via PayPal, you will be emailed your answer. Remember, be specific about auto repair problems if using a paying website.

Not a Substitute for a Mechanic

While the Internet is a great tool for diagnosing common car problems, it's important to remember that this type of advice isn't a substitute for taking your car to a good mechanic. Many car problems can present safety issues if not properly diagnosed. Your best bet is to diagnose your car problem online as well as you can and then take the information you've gathered to the auto repair shop. You'll be a confident, informed consumer, and your mechanic can use your research as a starting point for fixing your car.

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Diagnose a Car Problem Online