6 Signs that Your Vehicle’s Exhaust System Needs Attention

Internal combustion engines produce exhaust gases that can be dangerous if breathed in for too long. The primary purpose of the exhaust system is to keep these gases far away from you–though it also serves other purposes, including reducing engine noise and decreasing pollution. So, it’s important to keep an eye (and ear, and nose) out for signs that the exhaust system isn’t performing as it should be. Below are six possible symptoms.

6. Vibration/Shuddering

There are many things that can cause your car to vibrate, and most of them aren’t good. While vibration is often caused by non-exhaust-related problems, trouble with the exhaust system is still a possible cause. One of the hangers or brackets that hold the exhaust pipes against the underside of your vehicle may have come loose, or the pipes may have become misaligned. A failed muffler or clogged catalytic converter could also cause vibration. Another common cause is an exhaust leak. As exhaust gases escape through a small hole, they may cause the car to shudder.

5. Loud Engine Sound

The muffler that’s located near the end of the exhaust system serves to muffle the sound of the engine. If it’s damaged or not working the way it should, the engine will sound much noisier. However, leaks located before the muffler in the exhaust system can also lead to a loud engine sound, so pinpointing the exact location of your exhaust leak can be difficult without professional help.

4. Drop in Power & Fuel Efficiency

If you find you’re filling your gas tank more often than you used to, it may be due to trouble with the exhaust system. This is because the engine is working harder and using more fuel to try to compensate for the problem. In addition, you may find that getting up to speed is tougher, since exhaust leaks and other exhaust problems can keep your Subaru from performing at its peak.

3. Scraping or Rattling Sound

If it sounds like something is dragging beneath your car, scraping or rattling against the road, it’s time to pull over immediately. This is likely to be an exhaust pipe that has come loose. It’s dangerous to drive with a dragging pipe, and it can create a danger to cars behind you due to flying sparks. That danger to yourself and others only grows if the pipe snaps off completely.

2. Exhaust Smell

The smell of exhaust in your vehicle is never a good sign, and it may be due to an exhaust leak. If you notice that the exhaust has the scent of rotten eggs, it may be due to a failed catalytic converter. Exhaust gases contain a small amount of sulfur, which the catalytic converter then converts to odorless sulfur dioxide. If it’s not doing its job, the sulfur will still give off its characteristic rotten-egg smell.

1. Illuminated Check Engine Light

The oxygen sensors and the catalytic converter are important components of your vehicle’s exhaust system. The oxygen sensors read the level of oxygen in the exhaust to make sure that your car is getting the right fuel/air ratio, and the catalytic converter transforms some of the more harmful pollutants generated by combustion into less harmful compounds. Trouble with either of these components may send the signal to illuminate the check engine light.

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What the Color in Your Exhaust Means

If you own a car with a modern diesel engine dated 2008 or newer, your vehicle shouldn’t emit any smoke while your vehicle is running. Modern diesel engines have exhaust after-treatment systems that prevent this from happening. Even older car engines dated pre-2008, which do not have exhaust after-treatment systems, should emit only a small amount of smoke. 

A little white smoke isn’t anything to be worried about. You’ll likely see white smoke shortly after you start your engine during colder temperatures. After a few minutes, your engine will reach its average running temperature, and the smoke should dissipate. Other than this scenario, you shouldn’t see any other smoke come from your exhaust. If you notice smoke of any color coming from your car’s exhaust, take your vehicle in to see a mechanic who specializes in diesel and auto repairs.

Different colors of exhaust smoke are indicative of different issues. Learning what different smoke colors mean will help you better identify your engine’s problem. Let’s take a look at the most common smoke colors and the issues they represent. 

Black Smoke

If your car emits smoke that is black or dark grey, there is partly-burned fuel blowing out of your car’s combustion chamber. If your car’s fuel is only burning partially, you may have overloaded fuel into your vehicle. Black smoke is also a sign that your car engine doesn’t have enough air for proper combustion. This may also mean that there isn’t enough time given to burn the fuel.

When your car emits black smoke, you may notice that your car is lacking power or that you’re having problems with fuel economy. Taking your car in for repairs will help to alleviate these issues and improve your engine’s performance.

White Smoke

White smoke is a result of unburned fuel particles passing through your car’s combustion chamber and out of the exhaust pipe. As previously mentioned, white smoke is related to lower temperatures in the combustion chamber. When the chamber isn’t hot enough, some fuel particles fail to ignite. Don’t worry too much if you see white smoke in colder climates. Your car’s engine will warm up as you drive, and your combustion chamber will begin to burn all of the passing fuel particles. 

Blue Smoke

If your car emits blue smoke, there is engine oil burning in your combustion chamber. This could be due to worn out piston rings, broken valve sleeves, or failed turbocharger seals. In cases of blue smoke, auto repair professionals usually opt to run a compression test on the car’s cylinders. If the car passes the test, they then look into the car’s turbo intake piping to check for oil. 

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