How to Diagnose Smoke Coming From Your Car's Exhaust

How to Diagnose Smoke Coming From Car Exhaust

For most drivers, seeing a light vapor trailing your car isn’t an unusual occurrence. But, if you see different colored exhaust fumes, it’s time to pay attention to your car. Your vehicle may not be flashing warning lights, but the smoke coming from your exhaust may indicate that something isn’t working properly. Here's how to diagnose smoke coming from your car's exhaust.

Blue Smoke

Blue smoke is a clear sign that your engine is burning oil. Worn valve guide seals or piston rings can cause oil to leak past moving parts and into the combustion chamber where it’s burned up with fuel. Burning oil can also cause rough starts, as the leaking can ruin the car’s spark plugs. This kind of smoke requires immediate attention and, often, expensive repair and replacement parts. If the car is turbocharged, blue smoke can also indicate that the blower is in need of repair or replacement.

Grey Smoke

Grey smoke is difficult to diagnose by itself, so it should be monitored it closely. Like blue smoke, it can mean that the car is burning oil or suffering from a bad turbocharger. It can also be the result of a faulty transmission vacuum modulator, which causes transmission fluid to get sucked into the engine and burned, or a clogged air filter. In any case, these problems can cause significant damage to your vehicle if not examined by a seasoned mechanic.

Black Smoke

Black exhaust smoke means the engine is burning too much fuel. You should have your mechanic check your air filter and other intake components such as fuel sensors, injectors, return lines, and the fuel pressure regulator. Black smoke is usually the easiest issue to diagnose and fix, but burning extra fuel will definitely affect your fuel economy.

White Smoke

White smoke is usually nothing to be concerned about, as long as it’s thin, like vapor. This kind of smoke is the result of normal condensation buildup inside the exhaust system, and will disappear quickly. But thick white smoke can indicate that the engine is burning coolant. This can be the result of a serious issue like a blown head gasket, a damaged cylinder head, or a cracked engine block – all of which are costly repairs. Even small coolant leaks can lead to overheating, or mix with oil, and cause serious damage to the engine.

How to Diagnose Smoke Coming From Car Exhaust With V&F

At V&F, we offer:
  • Exhaust Repair & Replacement
  • Muffler Repair & Replacement
  • Tailpipe Repair & Replacement
  • Catalytic Converter Repair
  • Exhaust Manifold Repair
  • Custom Exhaust Fabrication
  • Exhaust Upgrades
Our expert mechanics can diagnose and repair problems with your exhaust, and perform regular maintenance to prevent further issues. Call us at (413)314-2280 or schedule an appointment online. Schedule Service This article was originally published in 2017 and has been updated.

Written by Nicole Palange