BMW Diesel - Turbo Common Faults M47/M47N/M57/M57N
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    BMW Diesel - Turbo Common Faults M47/M47N/M57/M57N

    BMW Turbocharged Diesel Engines use Garrett Variable Geometry Turbochargers(VGT) also known as a Variable Vane Turbocharger, these early VGT's, up to Sep 2003, use the vacuum system to operate the actuator
    which in turn controls the vane movement, over time these vacuum pipes are prone to collapsing & failure and can affect turbo operation, so replacing them is advised with 3.5mm bore cotton braided
    vacuum pipe, readily available for 2/metre from ebay or GSF.
    The later Turbochargers, circa post Sep 2003, are electronically actuated and these actuators can fail which can result in the costly replacement of both Turbo & actuator.
    Fortunately in some cases the actuator can be repaired individually, saving 's on the cost of not replacing the turbo.


    Regular synthetic oil and filter changes are a must to help keep the Turbo and engine in top condition, 7-8k changes are recommended.
    If you have the M47N/M57/M57N engines check the Oil Seperator is either the all plastic Vortex design (BMW part no. 11127799367)
    if you have the M47 engine or simply prefer using the foam 'loo roll' design, change it every 12-18months to ensure it doesn't clog up and increase internal pressures.

    If you have Turbo failure but without definitive symptoms a diagnostic scan can reveal specific error codes relative to the Turbo and its operation,
    also check all vacuum pipe connections and the condition of vacuum reservoir as it may be as simple as a disconnected vacuum hose.

    Some error codes and their usual fixes:-
    3f01 Boost Pressure Sensor - Failed MAP sensor, remove and cleaning may work but replacement may be required BMW Part No. 13617787142
    4521 Boost pressure control pressure too high & 4530 Boost pressure control pressure too low can indicate clogged Variable Vanes, check their operation manually or view the actuator movement when revving.

    Turbo Whistle - Some turbo's whistle more than others and can simply be a characteristic of general wear and tear but if the sound is reminiscent of a Police siren it is advised to check the play on the Turbos shaft asap.
    To gain access to the Turbo shaft wait until the engine is cool, remove the air pipe to the Turbo's inlet and grip the Turbo's shaft between thumb and forefinger to check the 'float' on the bearings,
    both side to side (radial play) and end to end (axial play).
    The axial float is generally between 0.025mm – 0.1mm which can hardly be felt, the radial float is generally between 0.3mm – 0.6mm which can be felt as a definite rock.
    This can only be a guide as a dial gauge is required to measure this accurately but if either 'float' movements feel excessive then the unit will most probably require immediate refurbishment.

    While the Turbo is accessible rotate the shaft and wheel by hand and feel for any drag or binding, push the shaft to one side and rotate to feel for any blade rub.
    Using a torch check the leading edges for signs of impact damage or wear, examine the outer blade tip edges and all the way down the profile to check for wheel rub, burred edges or scuffing.

    Unusually high oil consumption coupled blue exhaust smoke can be symtomatic of worn turbo seals, in extremely rare instances the engine can begin to run on its own oil
    causing plumes of smoke from the rear of the vehicle, if this happens switching the ignition off can prove pointless as the engine oil is being combusted so engine seisure is possible,
    try and stall the car by dumping the clutch in a high gear with foot on the brake!

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