Navigating the complexities of modern diesel engines often requires a blend of hands-on mechanical skills and advanced diagnostic tools. For owners of Mercedes-Benz vehicles equipped with the OM642 engine, encountering turbocharger issues can be a common chapter in the ownership saga. In this article, we delve into a recent experience diagnosing and resolving a sticky turbo actuator on a 2008 E320 Bluetec, showcasing how a systematic approach, combined with the power of Xentry diagnostics, can effectively “attack” and resolve such problems.
The journey began with subtle yet concerning symptoms: intermittent hesitations during low-speed acceleration, particularly noticeable when maneuvering through turns. These fleeting moments of power loss hinted at an underlying issue within the engine’s intricate systems. To effectively “attack” this problem, the first step was to leverage the diagnostic capabilities of Xentry, the professional diagnostic tool for Mercedes-Benz.
Connecting Xentry to the E320 Bluetec quickly revealed a fault code: 2592-001 Check component Charge pressure positioner. Positioner signals fault. Current and stored. This fault code immediately directed attention to the charge pressure positioner, more commonly known as the turbocharger actuator responsible for controlling the variable vanes within the turbo. Xentry’s guided test further clarified the issue, pinpointing the actuator’s limited movement and the accompanying sounds of a struggling electric motor – whining and clicking.
Upon physical inspection, the diagnosis was confirmed. The turbo actuator lever exhibited restricted movement, barely budging from its position. Disconnecting the linkage revealed a seized turbo vane mechanism. However, once freed from the stuck turbo linkage, the actuator itself moved smoothly, indicating the root cause lay within the turbocharger’s vane assembly, not the actuator motor itself.
To address the seized vanes, turbo removal became necessary. While not a task for the faint of heart, it’s a manageable procedure for experienced DIY mechanics. The process involves disconnecting several components on both the intake and exhaust sides of the turbocharger.
Turbo Removal Steps (OM642 Engine):
Intake Side:
- Disconnect the Intake Y-pipe.
- Remove the Charge air tube from the turbo outlet towards the intercooler.
Exhaust Side:
- Loosen the short pipe section between the turbo outlet elbow and the DPF. This section is secured by band clamps and a bracket bolt.
- Detach the Turbo outlet 90-degree elbow (2 bolts on top, 1 below).
- Disconnect the EGR 90-degree connector (4 bolts).
- Unbolt the Exhaust manifold connectors (3 bolts each side). Be cautious as these bolts are stretch-to-yield and should be replaced.
- Locate and remove two bolts holding a bracket to the top of the intake manifolds, positioned behind and below the turbo.
- Remove two T45 screws at the base of the turbo center section.
- Detach one E10 bolt holding a bracket to the front of the turbo.
- Unplug the turbo actuator electrical connector.
- Carefully lift the turbo straight up and out.
With the turbocharger removed, the next step was to access the VNT (Variable Nozzle Turbine) vanes. Removing the exhaust side housing revealed the sooty internals of the turbo. Close inspection confirmed the vanes were indeed obstructed by carbon deposits, hindering their movement and causing the actuator to work against excessive resistance.
The remedy was a careful cleaning process. Brake cleaner was used to flush out the carbon buildup, meticulously working the VNT mechanism until the vanes moved freely and smoothly. It’s crucial to note that the VNT assembly is designed to operate dry; lubrication is not recommended as it can exacerbate carbon buildup over time due to heat and soot accumulation.
During this process, the turbo impellers were inspected for damage, confirming they were in excellent condition with no play or signs of wear. Reassembling the turbo was straightforward, ensuring the alignment pin on the center section was correctly positioned with the notch in the exhaust housing.
However, the repair journey wasn’t without a minor setback. While dealing with the exhaust manifold, a broken bolt incident occurred. This highlighted a previous oversight where stretch-to-yield bolts had been reused, leading to failure. The resolution involved sourcing a replacement exhaust manifold, a relatively easy component to remove thanks to the use of copper-plated steel nuts.
Conclusion:
This “Xentry Attack Tested” approach – utilizing Xentry diagnostics to accurately pinpoint the fault and guide the repair process – proved highly effective in resolving the OM642 turbo actuator issue. By systematically diagnosing the problem, disassembling and cleaning the affected components, and adhering to proper reassembly procedures, the E320 Bluetec was restored to its optimal performance. This experience underscores the importance of combining diagnostic tools like Xentry with sound mechanical practices for efficient and successful automotive repairs, particularly in complex systems like modern turbo diesel engines. For further information and resources on Mercedes-Benz diagnostics and repair, visit xentryportal.store.
