IV. Common Faults, Phenomena and Causes of Turbochargers.
(1) Oil leakage (the most common failure).
1.The intake duct at the compressor end is leaking oil.
Symptom: Presence of engine oil in the air filter, excessive sludge in the throttle/air intake manifold, blue smoke during cold start, high oil consumption.
Possible reasons:
① The PCV valve of the crankcase ventilation system is clogged, causing the pressure in the crankcase to be too high and the engine oil to be forced into the oil return channel of the turbocharger.
② The turbine oil pipe was flattened and clogged, and the oil from the intermediate body could not flow back smoothly. The oil pressure pushed the oil seal open.
③ The wear gap of the floating bearing is too large, and the oil seal fails to function properly.
④ Long-term short-distance cold vehicle operation causes the engine oil to accumulate carbon, blocking the return oil channel.
2. Oil leakage at the turbine exhaust end, and the exhaust pipe emits blue smoke.The turbine oil seal ages and the bearing wears out. The engine oil leaks into the exhaust, and the high-temperature combustion emits blue smoke, and the three-way catalytic converter is prone to clogging and failure.
(2) Insufficient pressure boost, weak power output, and insufficient acceleration.Symptoms: Acceleration of the vehicle, lack of power when climbing, malfunction indicator light on, data indicating that the intake air pressure is far below the standard value.Possible reasons:
① The bypass valve is stuck and always open, resulting in a large amount of exhaust gas flowing directly, preventing the turbine from generating pressure (due to fatigue of the mechanical valve spring and carbon buildup clogging the valve).
② The intake pipe, intercooler, and vacuum tube have ruptured and are leaking air, causing leakage of compressed air.
③ The turbine impeller is covered with carbon deposits and oil stains, resulting in significant resistance during rotation.
④ The electronic relief valve actuator is faulty, and the ECU continuously instructs the valve to open.
⑤ The three-way catalytic converter is clogged, causing excessive back pressure in the exhaust system, and the exhaust cannot push the turbine.
(3) Excessive boost pressure, engine detonation, and fault alarm.Symptoms: Abrupt acceleration failure, engine fault indicator light on, reporting excessive boost pressure fault, and in severe cases, damaging the cylinder gasket.Possible reasons:
① The bypass valve is completely blocked by carbon deposits and cannot be opened. There is no exhaust gas diversion, and the boost pressure exceeds the limit.
② The vacuum pipeline of the relief valve has fallen off or ruptured, and the diaphragm has no thrust to open the valve.
③ The electronic control relief motor is stuck and cannot execute the valve opening command.
(4) Turbine abnormal noise.
① Whistle (continuous sharp screeching)
High rotational speed is obvious. There is air leakage in the intake/exhaust manifold, the impeller is slightly deformed, and there is air leakage through the shell gap.
② Metal friction sound (rustling/creaking)
Wear of the bearings, the impeller scraping against the shell (lack of engine oil, long-term high-temperature dry grinding, foreign objects entering the turbine).
③ Pressure relief hissing sound
Relieving the throttle is obvious. This is a normal pressure relief; the continuous hissing sound at idle speed is due to the improper closure of the bypass valve.
(5) The turbine has severe lag, and it lacks power at low speeds.Problem: The engine doesn't generate power until the accelerator is pressed for more than one second. It's difficult to overtake at low speeds.Possible reasons:
① Large inertia turbine combined with small displacement engine.
② Carbon deposits accumulate in the exhaust manifold and turbine housing, resulting in insufficient exhaust flow.
③ The bypass valve is slightly always open, causing the exhaust to be diverted at low speeds.
④ The exhaust pipe leaks, causing the exhaust energy to be lost.
(6) Impeller damage, turbine locking (severe failure).
Symptom: No boost at all, weak acceleration, abnormal noise during startup, and the turbine shaft cannot rotate.
Possible reasons:
① Insufficient or interrupted oil supply, high-temperature burnout and locking of the high-speed bearings.
② Foreign objects (carbon deposits fragments, exhaust metal debris) enter the turbine and strike the blades, causing the impeller to break.
③ Long-term high temperature, deformation of the intermediate body, and stalling of the rotating shaft.
④ Immediately shut off the engine after reaching high speed, the oil stops circulating, and the high temperature scorches the bearing seals.
(7) Excessive heat, turbine getting red-hot.
After a long period of heavy load climbing, the turbine housing gets extremely hot, which is a normal phenomenon. If it also gets hot at idle speed: exhaust blockage, excessive fuel injection causing delayed combustion, bypass valve stuck, and continuous accumulation of exhaust gas at high temperature.
V. Supplementary Maintenance Tips (To Reduce Malfunctions)
1. After starting the cold engine, let it idle for 30 seconds to allow the engine oil to fully lubricate the turbocharger before increasing the RPM.
2. After long-distance high-load operation, idle for 1-2 minutes before turning off the engine to avoid overheating without engine oil for cooling.
3. Use the full synthetic engine oil specified by the manufacturer throughout the process and replace the oil filter regularly.
4. Regularly clean the PCV crankcase ventilation valve to prevent excessive pressure inside the box from causing oil leakage.
5. Avoid using short trips for long periods as engine oil is prone to emulsify and accumulate carbon, blocking the return oil passage.