Car Smoking Under Hood But Not Overheating – Causes and Solutions

A proverb goes like ‘where there’s smoke, there’s fire’. Well, the smoke is nothing else but smoke when it’s an automobile engine because the ‘fire’ here is either an oil spillage or a malfunctioning component. Whether car smoking under hood but not overheating or the tailpipe belching smoke, it’s the indication of a more serious problem.

The exhaust pipe smoke could be of various colors and each color indicates a specific problem. But, that’s another topic. We’re going to discuss why there is white smoke under hood not overheating.

The Reasons for Car Smoking under Hood but Not Overheating

There could be several reasons for car smoking but not overheating. These are not serious issues but could turn serious if you don’t find out the root of the problem and fix it. The most common causes of this trouble are:

1. Oil Spillage

If the car smoking under hood but not overheating, it could happen due to the presence of oil outside the engine where it does not belong. Oil could go there when you are not careful when filling up the gas tank. Or, a spill could occur when you are adding oil to the crankcase.

If it is just an oil spillage at the wrong place, it won’t do any major harm except for producing a harsh, oily smell. It will quickly burn off without causing any long-term damage. However, if spills are a regular occurrence and you keep driving without wiping it off, some rubber or plastic parts could break down due to being submerged in oil for a long time.

car smoking but not overheating
Oil spills are the most common reason. Credit: Getty Images

2. A Leaky Component

It’s another form of oil spillage but the oil, in that case, oozes from a leaky component sitting high on the engine. It could be a leaky valve cover gasket that particularly happens in V-configured engines.

Replacing the valve cover gasket is an easy and cheap fix. However, ignoring the problem for too long will turn the minor leak into a bigger one and deteriorate the problem.

3. The Oil Filler Cap

White smoke coming from hood of car not overheating is a common issue in older engines. The oil filler cap in almost all the engines releases a faint whiff of smoke, which is a residue of the burnt fuel inside the engine. Older engines produce more hot spots, which make the car smoking under hood but not overheating.

Worn out piston rings and clogged PCV tube or valve are the culprits that cause this smoking issue. The timeworn rings make the pistons to siphon fuel into the cylinder where it burns and creates smoke. The smoke then gets past the piston rings. The crankcase ventilation is supposed to pull the smoke back into the engine for burning again. However, this does not happen when either the PCV tube or valve is faulty or blocked. In that case, the smoke gets released through the oil filler cap.

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4. Electrical Wires

A hot wire could also be the reason for engine smoking but not overheating. In that case, you will smell a pungent odor that is hard to miss. It’s hard to trace when it comes from the alternator’s copper wires. It oozes a subtle aroma-like smell that comes from ozone and hot metal. Nevertheless, you will get a strong odor if the alternator is burnt out completely. If that happens, the low voltage and check engine lights will also come on.

5. Coolant Leak

If there is a leak in the coolant overflow tank, it can cause occasional cases of steam coming from under hood but not overheating. The occasional smoke puffs can also be the aftermath of leaked and burn power steering or transmission fluid. In that case, there will be a cloud of smoke accompanied with a hint of chemical odor.

white smoke coming from hood of car not overheating
Don’t drive if the problem persists. Source: ruigsantos /

What to Do When Car Smoking under Hood but Not Overheating?

In most cases, smoking coming from under the hood is not a major issue. However, you have to be careful and follow some rules to keep it that way.

  • The smoking problem may cause showing low pressure in the oil gauge or lighting up the oil pressure indicator. If that happens, don’t keep driving the car. Take it to an auto servicing shop as soon as possible. Ignoring the problem is likely to end up with malfunctioning piston rings or stalling the engine.
  • If you detect smoke and low oil pressure while driving on the highway, try to park somewhere safe immediately and shut off the engine. If you have an extra gallon, add it to the fuel tank and restart the engine. Drive carefully to a safe place or a repair shop if the oil pressure improves or the light goes off. There is no other option but to tow the car to a garage given that the added oil makes no difference.

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