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Mercedes E320: Turbo death due to particle bombardment
The owner of an eight-year-old Mercedes E320 noticed a dramatic drop in performance of the V6 turbodiesel and went to the workshop. There it was diagnosed that the turbocharger was dead, but replacing it only provided short-term relief.
Mercedes E320: Turbo death due to particle bombardment
Luckily it happened on a country road with little traffic and not on the motorway, when the V6-cylinder turbodiesel engine of the Mercedes E320 suddenly put most of its 224 horses in the stable. With significantly reduced engine power, the sedan made it to the nearest Mercedes workshop, where it was immediately connected to the Mercedes Xentry diagnostic system. The engine management indicator light lit up - an initial indication of the possible source of the error.
The diagnostic steps in detail:
▶ The error code readout showed the following messages: Check exhaust back pressure sender due to control deviation - the exhaust back pressure is too high / The boost pressure actuator is faulty / Check the boost pressure control system - boost pressure too low / The signal voltage of the exhaust back pressure sensor is too high.
▶ The Mercedes technician assumed there was damage to the turbocharger, and indeed: After removing the device, damage was found on the electronically controlled actuators and the turbine blades.
▶ Replacing the GT20 VNT charger from Garrett helped, the V6 engine ran at full power again.
However, it would not be a diagnostic crime if the case had ended there. In fact, the E320 came back to the workshop just a few days later with the same problem. The second chapter of the diagnostic crime story began.
▶ The error codes showed the same picture, the turbocharger the same damage - the Mercedes technicians suspected a manufacturing defect in the replacement turbocharger and complained about the supposed "Monday device" to the supplier - the Viennese company Turbo Twins.
▶ The experienced turbo twins Walter and Manfred Müllberger took a close look at the charger and found small metal splinters that had gotten stuck in the actuators and had bent them.
▶ The turbine blades were also bent by the bombardment of the sucked-in parts, so it was at least clear that the turbocharger had worked properly.
▶ The search for the source of the metal splinters began on the vehicle and the engine's exhaust tract was closely examined.
▶ Conclusion: The source of the error was in the exhaust manifold, which is constructed with double walls. Walter Müllberger explains: "Due to the strong thermal influence, the inner tube can become brittle and crumble over time. The parts are sucked in by the turbo and destroy the blades, which rotate at up to 200,000 revolutions per minute." A defect that can occur after around 100,000 to 150,000 kilometers of driving.
▶ With the help of the TurboTwins, the case was solved, and Mercedes has since recommended that in the event of turbo damage on the V6 turbo diesel engine OM 642, the exhaust manifolds be examined closely - ideally with an endoscope. If cracks or broken metal parts are found, the manifolds must be replaced together with the turbocharger.