5 Commons Factors for Turbo Oil Leakage

Turbo oil leakage can result from a variety of factors, in this discussion we’ll pick 5 common factors for oil leakage – clogged air filter, poor oil return, leak in the exhaust system, increased crankcase pressure, and a collapsed turbine piston ring. A turbocharger should not leak oil under proper installation; however, oil leaks may lead to catastrophic damage to the bearing systems.

Clogged Air Filter

An air filter keeps dirt and debris from entering the engine. A clogged filter can lead to several problems, impeding the engine to work properly.

 Cause: A clogged air filter restricts airflow into the turbocharger, causing a vacuum/negative pressure in the compressor housing. This imbalance forces oil to lead past the seals.

 Effect: Purpose of turbo’s internal seals are to prevent oil leakage, but once insufficient airflow cause pressure differences, oil leaks into the intake or exhaust end of the turbo.

 Symptoms: These are the signs of oil leakage due to clogged air filter.

• When oil gets burnt, you’ll see blue smoke coming out from the exhaust.
• Clogged air filter also causes oil residue in the compressor housing.
• Insufficient airflow reduces boost pressure and affects performance.

 Solution:

• Check and replace or clean the air filter regularly.
• Use high-flow performance filters for improved airflow.

 

Poor Oil Return/Drainage

Turbochargers rely on gravity to drain oil back to the oil pan. It’s imperative that oil return pipelines work smoothly.

 Cause: During operation, if the oil return pipeline is deformed or blocked, the oil pressure gets too high in the middle, causing the oil to spill, to go back up and leak past seals.

 Effect: The buildup pressure in the center housing pushes oil out of the seals into the compressor or turbine housings.

 Symptoms:

• Oil leakage from the housing.
• You’ll see oil on the return line or on the fittings.
• When oil burns in the exhaust, smoke comes out as a result.

 Solution:

• Regularly inspect and clean the oil return line.
• The oil drain line should be straight and downhill, ensure there’s no sharp bends so that the oil flows freely to the top of the oil pan without restrictions.
• Check the diameter of the oil drain line. It should be at least the same size as bearing housing oil drain; the bigger oil drain the better. If drain line is smaller than the hole size it can restrict oil from flowing smoothly.

 

Leak in the Exhaust System

 Cause: Exhaust leaks before or around the turbo can cause fluctuations in pressure and temperature, affecting turbo performance.

 Effect: Pressure imbalance can disrupt the oil seal function especially at the turbine end, which causes oil leakage.

 Symptoms:

• Noises from the exhaust or sort near the leaking area.
• Imbalance boost pressure, losing performance.
• Smoke and burning oil smell from the exhaust.

 Solution:

• Inspect and repair any cracks, loose gaskets, or worn flanges in the exhaust manifold or connections.
• Make sure all the bolts are torqued properly and replace any worn gaskets.

 

Increased Crankcase Pressure

When the crankcase exhaust gas pressure exceeds the specified value, it increases the pressure in the turbocharger oil return line.

 Cause: When the oil return is not smooth due to crankcase exhaust gas pressure impacting the pressure in turbo oil return line to increase, it causes the sealing ring to leak.

 Effect: Once excessive pressure builds up in the crankcase, turbo oil seals leak easily.

 Symptoms:

• Oil leaks at multiple points such as turbo, valve cover…etc.
• Smoke coming from the dipstick or oil filler cap.
• Blue smoke from the exhaust as oil burns inside.

 Solution:

• Always check the ventilation status of the crankcase is functioning properly
• Inspect and replace the PCV (Positive Crankcase Ventilation) valve if blocked.
• Check for blockages in breather hoses.

 

Collapsed Turbine Piston Ring

Turbo seals, especially the turbine piston ring, act as barriers to prevent oil leakage.

 Cause: The turbine piston ring (oil seal) can wear out or collapse due to heat, contamination, or improper installation. A damaged ring fails to seal the oil, causing it to leak into the exhaust system.

 Effect: Oil leaks from the turbine end into the exhaust, resulting in burning oil and excessive smoke, potentially damage to the catalytic converter or diesel particulate filter (DPF).

 Symptoms:

• Heavy blue smoke from the exhaust.
• Oil residue in the turbine housing.
• Loss of boost pressure.

 Solution:

• Replace the turbine piston ring.
• Check for proper lubrication and cooling to prevent overheating.
• Verify proper installation of the replacement ring.

 

Most of the oil leakage is caused by other factors other than the turbocharger failure. Regular maintenance, including checking on the air filter, PCV valve inspection, and ensuring clear oil return lines, is essential to prevent turbo oil leakage. Promptly addressing these issues can avoid costly repairs and performance losses.