Troubleshooting Engine Issues: How To Tell If Diesel Is Burning Oil

At a Glance

This is because the oil is burning in the combustion chamber, creating a bluish-grey smoke.
If you notice that your oil level is dropping significantly between oil changes, it’s a good indication that your engine is burning oil.
A general rule of thumb is that a diesel engine should not consume more than a quart of oil between oil changes.

If you own a diesel vehicle, you know that they are known for their power and efficiency. But like any machine, they can experience problems. One common issue is oil burning, which can lead to decreased performance, increased emissions, and even engine damage. So, how do you tell if your diesel engine is burning oil?

The Telltale Signs of Oil Consumption

There are several signs that your diesel engine might be burning oil. These signs can be subtle at first, but they become more pronounced as the problem worsens.

1. Blue Smoke from the Exhaust

The most obvious sign of oil burning is blue smoke coming from the exhaust. This is because the oil is burning in the combustion chamber, creating a bluish-grey smoke. The color of the smoke can vary depending on the severity of the oil burning.

2. Oil Level Dips Rapidly

If you notice that your oil level is dropping significantly between oil changes, it’s a good indication that your engine is burning oil. Check your dipstick regularly and keep track of the oil level.

3. Increased Oil Consumption

A general rule of thumb is that a diesel engine should not consume more than a quart of oil between oil changes. If you are adding more than this, it’s a sign that your engine might be burning oil.

4. Engine Performance Issues

Burning oil can lead to several engine performance issues, including:

Reduced Power: Burning oil can cause a build-up of carbon deposits in the combustion chamber, which can reduce engine power.
Rough Idle: The engine may idle roughly or stall, especially when cold.
Increased Emissions: Burning oil releases harmful pollutants into the atmosphere, leading to higher emissions.

5. Oil Smell

A strong oil smell coming from the exhaust or engine bay is another sign of oil burning. This smell is often accompanied by blue smoke.

Common Causes of Oil Burning in Diesel Engines

There are several reasons why a diesel engine might start burning oil. Here are some of the most common causes:

1. Worn Piston Rings

Piston rings are responsible for sealing the combustion chamber and preventing oil from entering. Over time, piston rings can wear down, leading to oil leaking into the combustion chamber and burning.

2. Worn Valve Stem Seals

Valve stem seals prevent oil from leaking into the combustion chamber through the valve stems. As they wear down, oil can leak past the seals and burn.

3. Worn Cylinder Walls

The cylinder walls can wear down over time, creating gaps that allow oil to leak past the piston rings.

4. Blow-by

Blow-by is a condition where combustion gases leak past the piston rings and enter the crankcase. This can cause excessive pressure in the crankcase, forcing oil past the seals and into the combustion chamber.

5. Turbocharger Issues

Turbochargers can leak oil into the intake manifold, leading to oil burning. This is often caused by worn seals or a damaged turbocharger.

How to Diagnose Oil Burning

If you suspect your diesel engine is burning oil, it’s important to have it diagnosed by a qualified mechanic. They can use a variety of tests to determine the cause of the problem, including:

Compression Test: This test measures the pressure in each cylinder, which can help identify worn piston rings or other problems.
Leakdown Test: This test measures how much air leaks past the piston rings, which can help identify blow-by.
Endoscope Inspection: An endoscope can be used to visually inspect the combustion chamber and cylinder walls for signs of wear.

Addressing Oil Burning in Diesel Engines

Once the cause of oil burning has been diagnosed, the mechanic can recommend the appropriate repair.

1. Piston Ring Replacement

If the piston rings are worn, they will need to be replaced. This is a major repair that requires removing the engine from the vehicle.

2. Valve Stem Seal Replacement

Replacing worn valve stem seals is a less invasive repair than replacing piston rings. It can usually be done without removing the engine from the vehicle.

3. Cylinder Wall Re-boring

If the cylinder walls are worn, they can be re-bored and fitted with new piston rings. This is a more expensive repair than replacing piston rings or valve stem seals.

4. Turbocharger Repair or Replacement

If the turbocharger is leaking oil, it may need to be repaired or replaced.

Preventing Oil Burning in Diesel Engines

While you can’t completely prevent oil burning, there are several things you can do to minimize the risk:

Regular Oil Changes: Changing your oil regularly helps to prevent wear and tear on engine components.
Use the Correct Oil: Using the correct type and weight of oil for your engine is essential for proper lubrication.
Avoid Over-Revving: Over-revving your engine can put excessive stress on the piston rings and other components.
Don’t Drive with a Low Oil Level: Driving with a low oil level can lead to engine damage.
Regular Maintenance: Regular maintenance, including inspections and tune-ups, can help identify and address potential problems before they become serious.

Summary: Keeping Your Diesel Engine Running Smoothly

Burning oil in a diesel engine is a serious problem that can lead to decreased performance, increased emissions, and even engine damage. By understanding the signs of oil burning, the common causes, and the available solutions, you can take steps to prevent this problem or address it if it occurs. Regular maintenance, proper oil use, and prompt attention to any warning signs are key to keeping your diesel engine running smoothly for years to come.

Troubleshooting Engine Issues: How to Tell if Diesel is Burning Oil