A fine gauze filter sits in the oil feed line of the turbo, and soot and carbon particles coming from the EGR system block it. With less oil the bearing of the turbo overheats and fails. The fault appears above 150 000 kilometres, and comes sooner if the oil is poor or a long time passes between oil changes.
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The symptom is a loss of power under load, blue or black smoke, a metallic turbo noise and limp mode.
One check decides what the next step is: if the shaft of the turbo can be moved along its axis, cleaning no longer helps and the turbo has to be replaced. If there is no play, the gauze filter has to be cleaned or replaced, and the flow through the oil feed line has to be checked at every service.
Replacing the turbo on its own is not enough: the lubrication system has to be cleaned out as well, otherwise the new part goes the same way.
What to check
- Accelerate under load and listen to the turbo: a metallic noise shows a bearing fault
- Watch the exhaust: blue or black smoke and limp mode belong here
- Ask for a check: axial play in the shaft of the turbo means a replacement is needed