A technician is diagnosing a turbocharger on a 15 L heavy-duty diesel engine. They notice significant oil leaks from both the compressor and turbine seals. What is the most probable cause of this issue?

Question: A technician is diagnosing a turbocharger on a 15 L heavy-duty diesel engine. They notice significant oil leaks from both the compressor and turbine seals. What is the most probable cause of this issue?

Answer options: ✅ A restricted oil drain line from the turbocharger, causing oil to back up and push past the seals.

• Excessively high engine oil pressure due to a faulty oil pressure relief valve.
• A worn-out compressor wheel, leading to imbalance and seal damage.
• Low engine oil level, causing insufficient lubrication to the turbocharger bearings.

Correct answer: A restricted oil drain line from the turbocharger, causing oil to back up and push past the seals.

Explanation: A restricted oil drain line prevents oil from returning to the engine sump effectively, causing oil to accumulate in the turbocharger housing. This build-up of oil pressure can overcome the seal's integrity, leading to observable leaks from both the compressor and turbine sides. Engine oil level or high oil pressure are less likely to cause both seals to leak.