Car Repair and Maintenance

Major Reasons for Car Blowing White Smoke but Not Overheating

Car Blows White Smoke but Does Not Overheat

Suppose you encounter a problem like a car blowing white smoke but not overheating. A typical mechanic will say, “don’t panic.” Well, you should not panic—use this guide to figure out the problem and fix it.

Perhaps, you just arrived home from work and noticed the white smoke blowing out of my car. Upon checking the temperature gauge, it does not seem like your car is overheating. For the record, it is possible for a car to smoke white without overheating.

As such, this publication covers the major problems to look for and also proffers possibly working solutions.

car blowing white smoke but not overheating

Possible places white smoke could be coming from

Do not be quick to conclude that since there is white smoke, there is fire, especially if your car is not overheating. So, in your case, we assume that smoke is the problem and not overheating.

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Besides, white smoke is typically not catastrophic. Nonetheless, it can be a sign of more significant problems you need to address immediately to keep the car from causing a fire in your wallet—major expenses.

The 4 major places where white smoke is coming from in your car could be the exhaust, filler cap, engine, and electrical system. These are the areas this guide focuses on to help you possibly fix the problem yourself.

Reasons for car blowing white smoke but not overheating: how to fix

When you see white smoke from your car, which is not overheating, determine where the smoke is coming from and do the following to fix it:

  1. White smoke blowing from the exhaust

It is even common to have white smoke coming from the exhaust, even without the car overheating. White exhaust smoke can be followed by power loss, poor fuel economy, or cylinder misfire, so determine the possible causes for smoke from exhaust below:

  • Cracked cylinder head and coolant leak

If white smoke comes from your car when the engine is warm, you sense a sweet smell or during acceleration, the coolant found its way into the engine combustion and is burning with fuel.

It is quite common for a coolant leak to cause a car to blow white smoke without overheating. This is typically a result of a crack in the cylinder head, and sometimes the engine block.

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Even the smallest crack is all it takes for coolant to find its way in the wrong place, mixing with the engine oil, which causes contamination. The result, of course, is the white smoke and a sweet smell you get, but the vehicle does not overheat.

How to fix

The solution is to have a mechanic fix the leak. Otherwise, the coolant level will drop, causing the vehicle to overheat. This can damage the head gasket and other internal parts.

  • Condensation

Condensation causing cars to blow white smoke but not overheating is quite common, and you have nothing to worry about here. Normally, when you start the engine in cold weather, your hot exhaust gas comes in contact with external cold air, which causes condensation and steam.

You should see small white smoke from the exhaust, typically without any scent. This should clear up within 1 minute.

  • Water

Water can get in the exhaust system, causing the white smoke you see when your vehicle is not even overheating.

Water leaks from dirty turbos that get into the cooling channels will affect the engine performance. You may not notice the difference, but your car will not run smoothly.

How to fix

If you figure out that the problem is faulty turbos, have them replaced to prevent water from leaking.

  • Damaged engine block

If the engine block cracks, you would get the white smoke, which needs immediate fixing. Otherwise, would be spending even more because even fixing a cracked engine block is still costly.

Have a mechanic inspect the car through a professional diagnosis to determine your best solution.

  • Damaged fuel injector

You would also find white smoke from your vehicle exhaust if the fuel injector is faulty. The fuel injector is responsible for accurately timing and injecting fuel into the internal combustion chamber.

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As such, if the O-ring of the fuel injector is leaky or the injector is stuck open, it will inject excessive fuel the combustion chamber can’t completely burn. The excessive fuel is then released as white smoke.

How to fix

The fix for this white smoke problem is to replace the fuel injector or its O-ring. It is an inexpensive measure. Since it can be challenging to know which fuel injector is precisely bad, mechanics tend to recommend replacing all of them.

  1. White smoke blowing from the oil filler cap

  • Burned residues

If you have an older car, you would notice the white smoke from the oil filler cap. This is due to the residue buildup on the cap, so as the engine heats, the residues burn, causing white smoke.

  • Worn piston rings or cylinders

You would also notice white smoking from a car that is not smoking as a result of worn piston rings or cylinders. What happens here is that these worn components allow the pistons to tuck oil into the cylinder. The oil reaching here burns, shooting past the piston rings.

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  • Faulty PCV valves or tubes

When the PCV (positive crankcase ventilation) valves are broken, they can be the reason for the car blowing white smoke but not overheating.

Normally, the crankcase ventilation valve draws back white smoke is drawn back into the engine. If broken, smoke rises from the oil filler cap.

How to fix

PCV valves need to be fixed to prevent them from sucking oil into the engine and burning it there. An immediate fix will stop the smoke and prevents escalation to a more expensive problem.

  1. White smoke from the engine

Oil leaks and an error in the ECM (Engine Control Module) will cause your car to produce white smoke without overheating.

  • Oil leak

Oil may be burning in your car if you find white smoke from the hood, particularly from the engine, smelling like asphalt or tar with a bluish tone.

Oil could be leaking somewhere in the car, dripping onto the exhaust manifold or catalytic converter, and then burning, which causes white smoke. Oil can even find its way into the fuel system, burning from the running engine.

How to fix

The solution is to have the vehicle inspected thoroughly for an oil leak. Oil leak would occur as a result of damaged valve cover gaskets you need to replace.

  • ECM error

Computer problems also cause the white smoke in your car. The Engine Control Module (ECM), for instance, can transmit wrong signals to the fuel injectors, resulting in irregular fuel delivery. Thus, the engine receiving insufficient or excessive fuel will blow white smoke.

How to fix

Have a mechanic reset or reprogram the ECM. You may even be able to reset the computer simply by unplugging the car battery for some minutes to resolve the problem.

Otherwise, contact your dealership for ECM reprogramming by experienced mechanics.

  1. White smoke blowing from electrical system

It is quite uncommon for an electrical system to cause white smoke when the car is not overheating since car wires are covered and insulated. But this does not rule out the possibility in your car, which could be caused by hotwire or, even the alternator.

If this is a hotwire problem, you will get an intense and sharp smell from the smoke. However, if the alternator is smoking, it could mean the alternator is fried. You would typically get the engine light or low voltage light on your dashboard if the alternator is damaged.

Safety steps when you notice your vehicle blowing white without overheating

If you are driving when you notice the white smoke coming from your car, you want to pull over to the side of the road. Nope, don’t call the mechanic so fast, unless it is getting late.

You need to DIY some troubleshooting measures to determine the cause of the white smoke. If you have no knowledge of cars, it is probably not the right time to attempt a DIY—call the mechanics to your rescue.

Also, you may not have the proper equipment or tools to fix the problem immediately; this is another good reason to drive to the nearest repair shop. Most of the time, it is worth it to fix the problem immediately before it escalates.

If you think the problem is severe and do not feel comfortable driving, call a roadside assistance provider to have your car towed. Some mobile mechanics will also visit your car at the spot to get it back in shape.

Latest posts by Bernard Juchli (see all)

Bernard Juchli

Bernard Juchli is an experienced racer, mechanic and team owner who trusts Avon Tyres.Bernard is the lead driver and force behind his Big Dog Garage Race Team. He is the General Manager and Chief Mechanic of Jay Leno’s Garage. Bernard and his crew of seven are responsible for all repairs, restoration and fabrication of Jay’s incredible automobile and motorcycle collection.

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