You must have seen white smoke coming out of the exhaust pipe of a car at least once. But have you ever caught yourself wondering what might be the main causes of white exhaust smoke and how to fix the problem?
Since your tailpipe is the engine’s outlet for emissions, it’s normal for vapor and smoke to be released into the atmosphere through here. Most of the colorless gases emitted from the engine are harmless, and there’s really no need to panic. But some types of exhaust smoke are an indication that there’s an issue with your engine, and you need to get it checked as soon as possible.
Exhaust emission can be of different colors ranging from grey, blue, bluish-white, each with distinct causes.
It is advisable to take your vehicle to a technician or mechanic if it’s giving off white exhaust smoke, but before doing that you will need to first evaluate the severity of the problem so you don’t end up paying for more than you need to.
A good rule of thumb when evaluating the exhaust emission is the thicker the smoke, the greater the seriousness of the issue. For instance, if the white smoke is of very low density, like water vapor escaping from a boiling kettle, and disappears immediately, then you have nothing to worry about as this is quite normal. But if the smoke is very dense and for a cloud of smoke behind the vehicle, then you have a problem.
We’ve already mentioned that white exhaust smoke varies in thickness, light as water vapor or very dense it forms a cloud of smoke.
When you notice white smoke when you start the car, accelerate, or idle, what this is telling you is that water or coolant is getting vaporized. To confirm this, simply use your hand to control some of the exhaust smoke to your face (i.e. don’t place your face directly opposite the exhaust pipe) and smell the smoke. It is most likely coolant if it has a sweet smell, and this is one serious problem.
Let’s look at the main causes of white exhaust smoke and how to fix the underlying cause.
In colder climates, it’s not uncommon to see white exhaust smoke that disappears quickly coming out of a car. This is no cause for alarm since it is simply condensation being heated into water vapor. In other places that have cooler morning and evening, you’ll notice this only at startup and then less than 2 minutes later nothing else.
Another reason behind white exhaust smoke is an oil leak. You see, engine oil is thicker than gasoline, besides that, it wasn’t even meant to be combusted by the engine. So, when oil finds a way into the combustion chamber due to faulty piston rings or valve seals, you’ll notice thick, persistent white or light bluish smoke coming out of the exhaust, and it gets worse as the leakage continues.
Not only is this bad for the engine components that are not getting enough lubrication because the oil is leaking into the combustion chamber, but the oil in the combustion chamber also reduces the efficiency of the engine and covers the spark plugs in soot, thereby resulting in starting problems, misfiring, etc.
The smooth and easy way to fix this issue is to take your car to a qualified technician immediately you notice the problem.
Internal coolant leakage is another cause of white exhaust smoke. In the introduction to this section we mentioned that when the coolant leaks into the combustion chamber, the white smoke produced has a sweet smell. If you suspect that the coolant is leaking, but the smoke doesn’t have a distinct sweet smell, then you’ll have to check and confirm that the coolant reservoir level is at the recommended level.
Even if you notice a weak but sweet smell from the exhaust emission and the coolant level is low, you need to take action immediately because if left unchecked, the leaking coolant can also contaminate the engine oil and turn it into a milky shade.
The best way forward is to get this fixed by a mechanic, but if you want to DIY make sure that the engine is cold, or at the very least warm, before you open the reservoir cap else you could sustain serious burns. If the coolant is at the normal level, then you’ll have to perform a cooling system pressure check so you can pinpoint the exact place where the coolant is leaking from.
The main function of the fuel pressure regulator is to supply the engine with an adequate amount of fuel-air mixture necessary for the engine to run efficiently. When your fuel pressure regulator is faulty the engine will either be flooded with fuel, some of which escapes without being properly combusted, or the engine will be starved of fuel leading to misfiring and jerky movements. In either case, you can expect abnormal exhaust emission as the engine struggles to operate with the fuel supply.
If your vehicle runs on diesel, ten white exhaust smoke means that the fuel injector pump timer is no longer working. This pump has a precise timing to ensure that the diesel is delivered exactly when needed to prevent fuel wastage.
So, if you see white or dark grey smoke from your exhaust pipe, then you’ll need to get the service of a qualified technician.
Sometimes the problem of incorrect fuel being injected into the combustion chamber isn’t as a direct result of a faulty fuel pressure regulator. If your engine control unit has a little glitch, maybe from a power surge or faulty alternator, it may throw the timing of the fuel injector off-balance. This doesn’t mean that the fuel injector is faulty and needs replacement. What it means is that you have to get the engine control unit reprogrammed to restore the correct fuel injection timing.
In most vehicles simply disconnecting the battery and turning off the ignition for a couple of minutes is enough to reset the computer and restore the fuel injection timing. If that doesn’t work for you, you can get it done at your mechanic’s place or the dealership who is familiar with the steps to reprogram your vehicle’s ECU.
This is the worst-case scenario because it is the one that will cost you hundreds of dollars to fix. If your engine block has a crack in it, then white smoke will be produced and this isn’t the only problem you’ll experience. Cracks in the engine block are difficult to troubleshoot without the correct tools. So your best bet is to get the vehicle inspected by a mechanic.
In most cases, the problems listed above are the main causes of white exhaust smoke coming out of your vehicle, but other than these few mentioned here, malfunction in other parts might produce similar symptoms like the ones above (except for the sweet smell, that’s strictly coolant leak).
Sometimes the issue might even be a combination of two or more faulty parts, or it could be one problem that wasn’t fixed which led to another more complicated problem. Either way, it’s recommended that you fix the problem while they are still small and affordable to fix. You might have to replace entire parts, which can be a big drain on your pocket, but fixing the problem early will reduce the chance of it developing into something complicated that might make you abandon the car for some time.
We’ll briefly go over possible solutions for your smoke problems, but you’ll need to exercise caution while working with the car parts. If you don’t feel confident fixing the problem by yourself or are not familiar with the workings of the parts, then you should 100% get the service of a qualified technician. The reason for this is because a poor or half-fix might end up turning your problem from a molehill to a mountain, and more problems in the near future.
If the white exhaust smoke produced by your car smells sweet, then you have to check the coolant left in the reservoir. You should only attempt to open the reservoir when the engine is cold, otherwise you might sustain serious injury from the hot steam trapped inside the tank.
Sometimes the smoke might have a sweet smell, but the coolant in the reservoir is still at the recommended level. In this scenario, you’ll need to perform a cooling system pressure check to pinpoint the exact location and severity of the leak.
The next place to check for a possible fault is the intake gasket.
Open the hood of your car and look for the intake gasket – you might need your car manual if you aren’t familiar with the engine compartment. There’s a gasket that seals the intake manifold to the head. This is the component that is responsible for the distribution of the fuel-air mixture to the different chambers, and if it is faulty, the coolant will leak into the combustion chamber, leading to the sweet smell in the exhaust smoke.
If there are no visible damages, move on to the head gasket. The head gasket seals the cylinder head and prevents the coolant from leaking into the combustion chamber. When damaged coolant has free entry into the combustion chamber, leading to sweet-smelling white smoke.
If after inspecting both parts you can’t find any fault, then I advise you get the help of a mechanic. Any damage found might be a bit expensive to fix, but will extend the lifespan of your car in the long run.
The takeaway is that you only have to worry about white exhaust smoke when it is thick, smells sweet, or doesn’t clear up in less than 2 minutes after starting your engine. If your vehicle keeps producing white smoke after the stated period, you’ll need to troubleshoot and fix the problem as soon as possible.
