Unusual Smoke: Why Is Smoke Coming From Under Hood But Not Overheating?

Smoke coming out from under the hood is usually a sign of engine overheating, but what if your car is not overheating? This article explains possible reasons for this unusual smoke and what to do about it.

Possible Reasons for Smoke Coming From Under Hood But Not Overheating:

  1. Oil Spillage: Engine oil can leak from several places, such as valve cover oil seals, cracked valve covers, cracked timing covers, and faulty crankshaft oil seals. If oil spills onto a hot engine component, it will burn off and produce smoke. This is the most common reason for white smoke coming from under the hood but not overheating.
  2. Electrical Wiring Issues: Hot or burning electrical wires can also cause white smoke from under the hood. If the smoke is coming from a hot or burning electrical wire, you will perceive a pungent odor. If the issue is from the copper wire in the alternator, you won’t perceive the smell unless the alternator is completely burnt.
  3. Smoke from Battery Terminals: A poor connection at the battery terminal or at the other end, or a shorted positive battery terminal can cause smoke from the battery. If you have loose or corroded battery terminals that are preventing good connection, you will see arching on the battery connections. Smoke from car batteries is dangerous and could cause explosions.
  4. Exhaust Leaks: A leak in the exhaust system, such as a damaged pipe or cracked exhaust manifold, can cause smoke to emanate from under the hood.

What to Do If My Car Starts Smoking But Not Overheating?

If you see smoke coming from under the hood but not overheating, do not ignore it. Although it may not be a major issue, ignoring it can lead to catastrophic problems like battery explosions and fire outbreaks. Here’s what to do:

  1. Check for Oil Leaks: If you suspect a fluid leak, check the engine bay for oil leaks. If the low oil pressure light is illuminating on the dashboard due to oil leaks, do not drive the vehicle. Top up the oil until it gets to the normal oil level mark on the dipstick.
  2. Fix Burning or Shorting Wires: Trace the smoke and see if there is any arching or burning electrical wires. If there is, it could be a positive wire is shorting somewhere. Turn off the vehicle and locate and separate the shorting wires or contact your mechanic.
  3. Clean the Battery Terminals: If the smoke is coming from the battery terminals, thoroughly clean the cables and the battery terminals. After that, retighten them properly. Also, check the small wires that connect to the positive battery cable and ensure they are not shorting somewhere.
  4. Check the Exhaust for Leaks: Finally, check the exhaust for leaks. If the exhaust pipe or manifold is cracked or damaged, it can cause the smoke. Exhaust leaks are easy to identify. If the smoke is coming from the exhaust, the engine will be making a loud and aggressive noise.
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Smoke coming from under the hood is a sign of a problem, even if your car is not overheating. It’s important to address the issue before it escalates to a major problem. The most common reason for smoke coming from under the hood but not overheating is a small amount of engine oil and other fluids leaking onto or spilled on the exhaust system or on a hot engine part. If you’re not sure what’s causing the smoke, contact your mechanic to find and fix the root cause.

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