Home | Exhaust | Blue Smoke from Exhaust: 6 Fixes

Blue Smoke from Exhaust: 6 Fixes

March 18, 2024 | Victor Lukasso

What Does Blue Smoke Mean?

If a car engine is burning oil, one of the signs it will show is blue smoke. This occurs when the piston rings, valve guide seals, or other engine components are worn or damaged, causing oil to leak. The oil flows into the combustion chamber, mixing with fuel and creating blue smoke. In addition to the smoke, it produces an unpleasant odor that is unhealthy to breathe.

Major Causes Of Blue Smoke From Exhaust

There are numerous causes of blue smoke coming out of the exhaust. Also, there are two types of blue smoke.

  1. Blue smoke from the exhaust when starting
  2. Blue smoke from the exhaust when accelerating

What Makes Blue Smoke From Exhaust When Starting?

1. Bad Valve Seals

If you notice blue smoke from your non-diesel car’s exhaust right after you park, faulty valve seals could be to blame. All engines have valves that mechanically open and close to let air and gasoline into the engine and exhaust gas out. The rocker’s arm applies pressure to the valves, and oil can collect on top of them. Valve seals are supposed to stop the oil from flowing into the engine, but if they fail, the oil will enter the engine and mix with the air and gasoline, causing the engine to emit blue smoke and an unpleasant odor.

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2. Damaged Glow Plug

One of the leading causes of blue smoke in cars is damaged glow plugs, particularly in diesel engines. Glow plugs are essential for igniting diesel fuel after the engine is started. However, once the engine has warmed up, the heat produced by the engine itself is sufficient to ignite the diesel fuel, and the glow plug is no longer needed.

A diesel engine with a faulty glow plug will produce blue smoke during startup until it reaches its optimal operating temperature.

What Makes Blue Smoke From Exhaust When Accelerating?

1. Stuck PVC Valve

In the event of seeing blue smoke emanating from the exhaust, it is advisable to inspect the PCV Valve (Positive Crankcase Ventilation Valve) since its purpose is to release the pressure that accumulates in the Oil Pan into the Intake Manifold, which provides air for the engine to function. The Intake Manifold also collaborates with the engine’s Air Filter. Thus, if the PCV Valve malfunctions, it will mix the oil with air and other gases in the engine, and the combustion of this mixture will produce blue smoke.

2. Blown Turbo

If your car is equipped with a turbo, a blown turbo can cause blue smoke. When a turbo blows, it results in a large cloud of blue smoke. This happens because of a broken oil seal in the turbo, which allows oil to enter the engine. Regardless of the situation, oil entering the engine can cause blue smoke.

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3. Worn Engine

Another common cause of blue smoke from the exhaust is a worn engine.

Pistons in engines move up and down the cylinder and are equipped with metal rings that create a tight seal against the cylinder walls. If the rings or cylinder are worn out, oil from beneath the piston will leak and mix with the air and gasoline, resulting in blue smoke during combustion.

How To Fix Blue Smoke From Exhaust

Identifying and fixing the cause of blue smoke from the exhaust is crucial to maintaining the health of your vehicle’s engine.

To begin fixing the issue, it’s essential to determine the underlying cause of the blue smoke. Once the cause is identified, immediate action should be taken to rectify the problem, preventing further damage to the engine and enabling a quick resolution.

1. Clean The Engine

Regular engine cleaning is crucial for maintaining your car’s health. If you see blue smoke coming out of your car’s exhaust, it is essential to check the engine as the cause may be debris buildup in the cylinder heads, preventing oil from reaching the combustion chamber.

In such cases, you must remove the valve cover and clean out any obstructions to avoid further damage to the engine. Regardless of the engine type, a malfunctioning engine is often the primary cause of blue smoke.

2. Fix the Bad Glow Plug

It is essential to fix a bad glow plug. If your car has a glow plug, the right thing to do is to get a replacement.

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3. Fix PCV Valve

Replacing a faulty PCV (Positive Crankcase Ventilation) valve is relatively easy and inexpensive. Begin by locating the tube that connects to the intake manifold, then follow it back until you reach the PCV valve. Remove the old valve and replace it with a new one.

4. Fix Valve Seals

If you’re looking to replace or repair your car’s valve seals, it is a task that can be done at home if you have the proper mechanical knowledge. However, proceeding cautiously and ensuring the valve doesn’t drop into the engine during the process is essential. Some individuals use compressed air through the spark plug opening to aid in the removal process.

The steps in changing valve seals may vary depending on whether the engine has an overhead cam. If it does, it will require additional work, as the cam must be removed to access the valve stem. You must remove the spring from the valve and the rocker’s arm before lifting and replacing the old valve stem seal with a new one.

While it is possible to do it yourself, having a professional mechanic handle the job is always a good idea to ensure a perfect fix.

5. Fix the Air Filter Modulator

You may need to address the air filter modulator to eliminate blue smoke from your engine. Locate the modulator, which may be integrated with the air intake system, and remove it carefully. Inspect it for damage or clogging, and replace it if necessary.

A faulty air filter modulator can cause a disruption in airflow to the engine, leading to issues such as blue smoke. Consult your vehicle manual or a professional mechanic if you need assistance.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.