Fault Phenomenon: Foton Raysta L18 turbocharger functions normally when cold. During high-speed operation (operating temperature), the turbocharger leaks oil, blue smoke comes from the exhaust, and eventually fails.

Troubleshooting Process:
– Checked engine oil quality: quality normal.
– Checked oil return line: return line unobstructed.
– Checked floating bearings: bearing clearance normal.
– Measured turbocharger rotor axial clearance at operating temperature: found excessive clearance.

Root Cause: Wear of the turbocharger floating bearings allows engine oil to leak into the exhaust passage.

Required Parts: Turbocharger assembly.