A coal handling plant reported that a Lovol FL958G wheel loader stalled suddenly under load and emitted thick black smoke from the exhaust. The engine would restart but lacked power.
The technician checked the "Air Filter" element. It was heavily clogged with coal dust. He replaced the filter. The black smoke reduced slightly, but the power remained low. He then checked the "Turbocharger." He removed the air intake hose. The compressor wheel had excessive axial play (wobble).
He focused on the "Wastegate Actuator" on the turbocharger housing. The wastegate controls the boost pressure. The actuator rod was seized in the "Closed" position. This meant the exhaust gas was constantly routed through the turbine, even at high engine speeds.
Because the air filter was clogged, the engine was starving for air. The seized wastegate forced the turbo to spin faster to try and force air in. However, the restriction was too great. The "Mass Air Flow Sensor" detected low air, and the ECU cut the fuel (causing the stall) to protect the engine. The black smoke was unburnt fuel due to the lack of air. The turbo play was caused by the "Thrust Bearing" wearing out due to the high speed and heat from the seized wastegate.
The repair involved replacing the turbocharger assembly (the bearing damage was irreversible) and the air filter. The "Intercooler" (air-to-air cooler) was pressure-washed to remove the coal dust buildup. The fuel filter was also replaced as a precaution. After priming the fuel system, the engine ran clean with full boost power.
