7 Causes Of A Car Blowing White Smoke From The Exhaust

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Seeing white smoke from your vehicle’s exhaust can be alarming, but it’s not always something to be concerned about. In some cases, it can be a normal occurrence (especially in winter). However, if the white smoke continues, it can indicate a serious issue that requires immediate attention to prevent potential engine damage.

Keep reading to understand the possible causes of white smoke coming out of your exhaust so you can differentiate between what’s normal and what needs to be resolved.

Top 7 Reasons White Smoke is Coming From Your Tailpipe

If you are in the unfortunate situation where white smoke continues to come out of your exhaust after you’ve let your car warm up for more than a couple of minutes, then you could have some internal problems taking place.

It’s important that you address the issue soon so that your engine and exhaust system do not get damaged in any way. Here are 7 of the most common causes of a car blowing white smoke from the exhaust pipe as well as the approximate cost to fix.

1) Condensation Burn Off

If you notice white smoke coming from your muffler, don’t automatically assume the worst. You may not have to worry because it could just be the accumulation of condensation causing that to happen.

In these situations, you will typically see this white smoke come out on cooler days. The smoke should only be coming out in small amounts after you start your engine. Then after about 30 seconds to a minute, the white smoke should clear up. If this is the case then you have nothing to worry about.

Cost to Fix: $0. No repair needed, as this is a normal occurrence and not a cause for concern.

2) Cracked Cylinder Head

Whenever your cylinder head is cracked or damaged, coolant will begin to leak out of it. This doesn’t need to be a big crack either. All it takes is a little bit of coolant to leak out and get mixed in with the engine oil.

Once that happens, the oil will become contaminated. The first sign of having contaminated oil is white exhaust smoke coming out of the tailpipe. As this continues, the white smoke will begin to have a sweet odor smell that won’t go away.

Cost to Fix: Repair costs can range from $500 to $2,000 or more, depending on the extent of the damage and the vehicle make and model.

3) Leaking Intake Manifold Gasket

Another area that can leak coolant is the intake manifold gasket. If your vehicle has water jackets that run through the intake manifold, a leaky intake manifold gasket could give you symptoms that are very similar to a head gasket leak, a cracked block, or a cracked cylinder head.

A bad intake manifold gasket is often cheaper and easier to fix than a bad head gasket. If you notice white smoke, make sure you do a bit of testing and diagnostics to figure out exactly which component is leaking. The cost of an inspection and diagnostics fee will pay for itself when you dodge an expensive repair bill for a part that didn’t need to be replaced.

Cost to Fix: Replacing an intake manifold gasket often costs between $250 and $600, depending on the vehicle and the complexity of the repair.

4) Oil Leak

If oil were to ever leak out of your piston rings or valve seals, then it would flow into the internal combustion chamber along with the fuel. Once the fuel and oil get mixed together, it will cause to come out of the tailpipe. You’ll likely see a blue-ish color smoke from your exhaust but it may appear to be white smoke to some people.

You would obviously want to fix this leak quickly because if the engine components are not being lubricated properly by the oil, then they’ll start to get worn out and damaged rather quickly. This will cause a whole other flock of expensive problems that you won’t want to have.

Cost to Fix: Fixing an oil leak can cost anywhere from $100 to $1,000 or more, depending on the source and severity of the leak.

5) Bad Fuel Injector

The fuel injector is responsible for injecting fuel into the internal combustion chamber at the exact right time. If you were to have a bad fuel injector, then it would cause white smoke to form because the proper amount of fuel did not enter the chamber at the right time.

Cost to Fix: Replacing a single fuel injector can cost between $200 and $800, while replacing multiple injectors can cost upwards of $1,500.

6) Engine Control Unit Error

If you have a faulty engine control unit or one that simply is glitchy, it may throw off the timing of the fuel injector. This doesn’t mean the fuel injector is bad or anything. It just means you need to fix or reprogram the engine control unit so that it can correct the timing of the fuel pump injector.

Often, you can simply unplug your car battery for a few minutes to reset the computer and the issue fixes itself. But if not, you would need to go to your dealership to get this done because it requires expert mechanics who are familiar with your vehicle’s engine to reprogram the engine control unit.

Cost to Fix: Replacing (and reprogramming) an engine control unit can cost between $500 and $2,000 (or more), depending on the vehicle and the extent of the issue.

7) Cracked Engine Block

The worst case scenario is that your entire engine block has a crack in it. These are the kinds of problems that will be the most costly to fix. You probably aren’t going to know which of these problems is causing the white smoke to get produced until you have a mechanic look over your vehicle and perform a diagnosis on it.

Cost to Fix: Repairing a cracked engine block can be quite expensive, often costing between $2,000 and $5,000 or more. In some cases, it may be more cost-effective to replace the entire engine.

How to Diagnose the Issue

If you notice white smoke coming from your exhaust, it’s important to diagnose the root cause before any potential engine damage can occur. Here are the steps to follow:

Check Coolant Level

The first step is to check your vehicle’s coolant levels. Locate the coolant reservoir (aka: overflow tank) under the hood. If the coolant level is below the recommended mark, it could indicate a leak causing the white smoke.

If that’s the case, the problem is serious if the leak is happening in the engine block or cylinder head. But it’s also possible you have a small leak elsewhere which isn’t the cause of the white smoke. This brings us to…

Inspect the Engine for Leaks

Perform a visual inspection of the engine bay, looking for any signs of coolant leaks. Check hoses for cracks, holes, or loose connections, and inspect the radiator for damage. Don’t forget to look underneath the vehicle for any pooling of coolant on your driveway or garage floor.

If you discover a leak, try to identify its source and assess the severity. Small leaks may be repairable, while larger ones may require professional assistance.

Check the Oil Condition

Checking the oil is a simple but important step. Remove the oil dipstick and look at the oil’s consistency and color. If the oil appears milky or has a foam-like texture, it may be contaminated with coolant, suggesting a potential head gasket issue.

In this case, don’t continue driving! If you ignore that warning, there’s a good chance severe engine damage will be the result and you’ll have even bigger problems.

Use an OBD2 Scanner

If your vehicle has an On-Board Diagnostics (OBD) system (all vehicles since 1986 do), an OBD2 scanner can help identify issues related to the coolant system, fuel injectors, or engine control unit.

Plug the scanner into your vehicle’s OBD2 port (usually located under the dashboard) and follow the device’s instructions to retrieve error codes. You can then research the meaning of the codes or consult a mechanic for interpretation and guidance on what to do next.

Inspect the Fuel Injectors

If the white smoke isn’t related to coolant, inspect the fuel injectors for any signs of leaks or damage. A faulty fuel injector can cause white smoke by allowing excess fuel to enter the combustion chamber.

To check the injectors, look for any visible cracks or leaks, and ensure the electrical connections are secure. In most cases, having a professional mechanic perform a more thorough inspection is highly recommended. They’ll be able to quickly identify a bad fuel injector and replace it if necessary.

Perform a Compression Test

A compression test helps determine if there’s an issue with the cylinder head, piston rings, or valves. This test requires a compression gauge and involves removing the spark plugs and cranking the engine to measure the pressure within each cylinder.

If one or more cylinders show low readings compared to the others, it could indicate a leak. Performing a compression test is not in the skillset of most car owners, so you’ll probably want to seek help from a mechanic.

Consult a Professional Mechanic

It should go without saying that if you’re unsure about the diagnosis or lack the necessary tools and expertise, consulting a professional mechanic is the best course of action. They have the knowledge and equipment to accurately diagnose the issue causing the white smoke.

Attempting to fix the problem yourself without the right tools or knowledge could lead to further damage and more costly repairs in the long run.

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KevinKevin has been fascinated by anything automotive since his first go-kart as a kid to his time working as an auto tech for Dodge after obtaining his degree in automotive technology. When he's not working on cars or writing about them, you can find him and his E36 M3 at an event with the local chapter of the BMW CCA. Latest posts by Kevin (see all)

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